Title: Asphalt Monomer reactions
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 Material Information
Title: Asphalt Monomer reactions
Physical Description: ix, 150, 2 leaves : ill. ; 28 cm.
Language: English
Creator: Leybourne, Allen Edward, 1934-
Publication Date: 1961
Copyright Date: 1961
 Subjects
Subject: Asphalt   ( lcsh )
Radicals (Chemistry)   ( lcsh )
Polymers and polymerization   ( lcsh )
Chemical Engineering thesis Ph. D
Dissertations, Academic -- Chemical Engineering -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Thesis: Thesis - University of Florida.
Bibliography: Bibliography: leaves 119-125.
Additional Physical Form: Also available on World Wide Web
General Note: Manuscript copy.
General Note: Vita.
 Record Information
Bibliographic ID: UF00097986
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000561367
oclc - 13516774
notis - ACY7296

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ASPHALT MONOMER REACTIONS














By

ALLEN EDWARD LEI BOURNE III


A DISSRTATION PRFSFNTFD T1 THFF GRN.I1.ATF. COUNCIL Of
THL UNI PL IT I OF FL:.RIl[E
IN PARTIAL L'LFILLIENT i-.F TIIF Ri I(. PIIrEl- NIN h OR THE-
DEGIRFF OCF L(.CII..F OF PHILO'(tPH I










UNIVERSITY OF FLORiDA

August, 1961





















Copyright by
Allen Edward Leybourne III
1961















ACKI;OtLE DGME NT


The author wishes to express his sincere appreciation

to Dr. Herbert E. Schueyer who, through his interest, stim-

ulated and guided this research program, to Dr. tack Tyner

and the other members of the Supervisory Committee whose

continued efforts and guidance made this research possible.

The author is indebted to Mr. John U. ealway whose assist-

ance in construction and maintenance of the experimental

equipment was invaluable. The facilities provided for this

research by the University of Florida, especially the Chemi-

cal Engineering Department, have been used with the greatest

possible regard for their value. The financial aid of the

fellowship grant of the Ethyl Corporation and the assistance

and fellowship provided by National Science Foundation Grant

NSF-ul4249 are also acknowledged with gratitude.












-iJi


4iiiiii














TABLE CF CITrTS


ACIHA1W DGENIMT ....................... ii

LISE F TABLES ........................ vi

ITC d6F FIGU3.LB ........................ viii

i. Mi w . . . . . . . . . . 1

II. T . . . . . . . . . . ..

A. Stabilized and/or Trapped Free Radicals Are Present
in Asphalts . . . . . . . . . .
Introduction . . . . . . . . . .
Causes of Free Radical Stability . . . . 5
Tree Radical Types Expected in Asphalts . . 7
Natural and manufactured Materials Having Stable
Free Radicals ................. 8
B. Principles Underlying Free Radical Induced
Polymerization ... . . . . . . . 14
A Theoretical Equation for Thermal Polymerization 18
C. The Influence of Stabilized Free Radicals . . .. 22
A Theoretical Equation for Polymerization Influenced
by Stabilized Free Radicals . . . ... 27

III. IWBm AL . . . . . . . . .. ..... 32

A. *Aerlals Used . . . . . . . .... 32
:i|r-olump Refidues . . . . . . . . 32
romi lidueu............... 32

ii rl .i .ailtee .. . . . . . ..... 31
. . . . . . q . . . 3b
i ...t l gent . . . . . . . 37
WlaScriptin aieW Operation ....... 37
I ld Aq t Description . . . 37
MtiO 2 t Opvrational Procedure .. 38
C. e. hms........... .................. 41
ii tlen Ali of Mrimoer by Hydroeaastion . 41
SMiiil hds of 01efin Analysis . . . .. 48


- .ii .


d.........





- iv -


Continued Page

A. Method of Calculating Monomer Concentration . . 54
B. Overall Polymerization Rate Constant Calculations 57
Empirical Determination of the Polymerization
Rate Constant . .. . . . . 57
Correlation of the Temperature Effect . . . 59
An Absolute Basis for the Overall Polymerization
Rate Constant . .. . . . . . 61
Determination of Constants for the Theoretical
Rate Equation .. . . . . . . 64
The flatran Program . . . . . . . 65
C. Calculation of Relative Free Radical Coacentrations 66
D. Estimation of the Absolute Free Radical
Concentration . . . . . . . . .. 67

V. mESBUI S . . . . . . . . . . . 68

A. Introduction . . . . . . . . . . 68
B. Correlation of Polymerization Rates with Monoma
Concentration . . . . . . . . . 69
C. The Arrhenius Correlation . ... .. . . ..... 73
D. Asphaltene Constituents Exhibit a Dominant Effect 75
K. Influence of a Pure Stable Free Radical . . . 82
F. Spectroecopic Evidence of the Existence of Stable
free Radicals . . . . . . . . . 85

VI. DISCUSSIOB (1 RESUIM . .... . . . . . . . 95

A. Introduction . . . . . . . . . . 95
B. The Taeoretical Kinetic Equation .... .. . . 95
Analysis of the Theeretical Enetic Equation
Related to Minmer Concentration . . .9
Analysis of the TWeoratical Kinetic Eqawtion
Related to Stable Free RaM cal Coacnntw lti .
C. A Ceoeriso n of Theory with E ,rMlment; CorwmAlit|||
of .boli.mrizatia Rate# wi;1th:b&ma=m r Comentiralie 1 ||00
D. AggxragatL i aid Solvauti ofa the Abhalteaws . .

VII. CMC M i .Ab . . . . . . . . . . . .
I. cI CSI .. .......... .............. i


1II. SUliWHi .toR W. .C . . . * * * ..
viii. sm .. .............. .......... I11

X.. Isum--W-I I .w . . . . . . . . . .


XI. I MEE ~ C-1 . . . . . . . . . . U9





- -


Continued Page

XII. APa i ICES ... ... .... .. ...... ... 126

A. Polymrization Run Ra Data . . . . . . 127
B. Calculated Values Determined for the Overall
Polymerization Rate Constant . . . . 143
C. Flatran Object Program for the I. B. 14. 650 Computer 145
D. temple Electron Spin BResnance Derivative Absorption
Curves of the Asphalt Residua . . . . .. 149


...a.........














LIST CF TABLES


Table Page

1. Free Radicals Stabilized in Pyrolytic Carbons . .. 10

2. Equations Derived from the Assumed Kinetic Mechanism for
Thermal Polymerization and Related Material Balances. 21

3. Equations Derived from the Assumed Kinetic Mechanism in
the Presence of Stabilized Free Radicals and Related
Material Balances . . . . . . . . .. 30

4. Properties of the Petroleum Residues Studied .... 33

5. Hydrogenation Blank Values for Several Asphalts ... . 41

6. Hydrogenation Blank Values for Two Asphaltenes . .. 44

7. A Comparison of Analyses for Styrene by Hydrogenation
with Other IMethods ... . . . . . . . 51

8. Densities of Styrene, S119 and Solutions of These
Materials ... . . . . . . . . . 63

9. A Comparison of Experimentally Determined Rate Constants
to Show Reproducibility . . . . . . . . 72

10. Free Radical Concentration of the Asphalts and
Asphaltenee Used in This Study . . . .... . 86

11. Graphically Determined Overall Polymerization Rate
Constant for Runs with the Gulf Coast Naphthenic
Residuum (8119), Styrene and Xylene . . . . . 87

12. Graphically Determined Overall Polymerization Rate
Constant for Runs with the East Central Texas Residuum
(8120), Styrene and Xylene . . . . . . . 88

13. Graphically Determined Overall Polymerization Rate IIII
Constant for Runs with 5000F. Air Blown S119 (R60-11),
Styrene and Xylene . . . . . . . . . 89

14. Graphicelly Determined Overall Polyamrization Rate Con-
stant for Runs with Various Petroleum Materials . . 9


vi-





-!!iii vii -


Continued

Table Page

15. Graphically Determined Overall Polyerizatiom Rate Con-
stant for Runs with Asphaltenes Derived from S119 the
Gulf Coast Naphthenic Residuum (B61-6), styrene and
Xylene . . . . . . . . . . . . 91

16. Graphically Determined Overall Polymrization Rate Con-
stant for Runs with Amphaltenes Derived from 5120 the
Bet Central Texa ReSiduum (S61-9), Styrene and Xylene 92

17. Grlahioally Determined Overall Polymerization Rate Con-
stant for Runs with Asphaltenes Derived fron 5120 the
Iut Central Texas Residuum (S61-9), o(-vinylnaphthalene
and Xylwe ...................... 93

18. GOrphically Determned Overall Polymerization Rate Con-
atent for Runs with l,l-Diphenyl-2-Picrylhydrazyl
(e61-11), Styreme and Xylene . . . . . .. 94

19. OCmtants Determined for the Theoretical Polymerization
Itate Constant Equation . . . . . . . .. 104

20. S~Mltmri4aton Ran Data for RW with the Gulf Coast
4Wllthenic llsiduta (8119), ityrene and Xylene ... 128

21. eJl eritatien Run Bta for Runs with the East Central
Sir w EfMiluum (S120), Styrene and Xylene . . . 131

22. iAi ncMtion Run Data for Runs with 5000F. Air Blown
Sc19 (160-11), StyKer and Xylaee . . . . . 134

23. Iirrt aim. Rmm i ta. far Rus with Various Petroleum
.t .I S..tyrem ................ 136

24. i len IRtun ust. f9r Rume with Asphaltanes Derived
i q i i .te Gulr Gouft Ktthmanic ealAduum (S61-6),
Aiift l. 4 yl06t .. . . . . . . . . 137

29. =ar.=n ~ ft for Rums with Aljaklt~ es aerived
ike~tCs Oients iexa ftetAu (s61-9),
S......139
~1i ............... 139

26. B l I h Ri"%.a fr MIWn with ABgaltenes Derived
7t = :::.64 I Ag$ 0gibal T Rmon niag (M61-9),

27. 110:i E &lilit for *ituna Mih 1,1 .4jiwnyl-
.... "i........... .....i. :il jii.e ignl i y.. .. . . . . 1 6

















Figure Page

1. Cross Sectional View of an Asphalteae Model . . . 12

2. The Influence of Solvent Ratio on the Yield of Petroleum
Asphaltenes . . . . . . . . . 35

3. Polymerization Equipment . . . . . . . . 39

I. Bomb Assembly . . . . . . . . . . 39

5. Selective Catalytic Micro-bydrogenation Assembly . . 45

6. A Scheatic Diagram of the Hydrogenation Apparatus .. 46

7. A Comparison of the Results of Analysis by Bruiaation
and Hydrogenation ................... 53

8. Vapor Pressure of a-xylene . . . . . . . 58

9. Calculation of Experimntlly Determined Overall
Polywriaztion Rate Constant . . . . .... 60

10. The Effect of Temperature on the Yete of Polymerization 70

11. The Effect of Temperature on the Wate of Polymerization 71

12. Arrhenius TePerature Correlation of Overall Polyeri-
zation Rate Constants . . . . . . . . 7:

13. summry of thbe OfrUa Polymrizatioua ate Constants
gMaized in -Lt Variom-Syeas- Stuadie . . ..

14. The Effect of Vari ion in As#hslt*ae Cmcina in e -t- 1
the Aelyierlatiln Rate Co t . . . . . .

15. Tte effect of Va st&L L in Asphalt Cnceatfst.A on tho. e
Solymeriamian bate feastant . . . .. . . 79

16. A Capwrieft of the lafl iene dt an Air Blown Ayihaltlite
tlSt of tA h M~aH fri r Which It iB Fre .ma- . 81


S ihlflh ii! Si!!!!! lilt -


mmm "iiiiiiiiiiiiiii





-ix -





Continued


Figure Page

17. The Effect of Variation in Asphalteme Cwemetration
on the Blyrization Rate Co ta . . . . . 83

18. The EfSect of Variation in the Concentration of A Pure
Free Radical on the Polymrization Rate Coantant . 8.

19. ualitative Apects of the Factors Affecting the
Ovresml Palyriraten Rate Coamtant . . . ... 98

20. A Caimarison r Theory with Experlasmt . . . .. 102

21. A CoWrleon of Theory with Experiment . . . ... 103

22. An Aephalteka Model Showing the Solvatlon effect
Occurring in Relatively Concentrated Asphalt System 109















I. IIiTRODUCTION


Asphalt has been used in a variety of ways since ancient times.

Archaeologists discovered that asphalt had been used as an adhesive

for building stones and paving blocks as early as 3800 B C. These

early asphalts were obtained from scattered sources formed by

nature's own refining of petroleum deposits through geologic pro-

ceases (10) The 114-scre Trinidad lake and the 1000-acre Bermudez

deposit in Venezuela are impressive examples of these natural

processes. In the United States, a naturally occurring asphalt-like

material called gilsonite is found in the Uinta River basin of Utah.

Today virtually all asphalt used commercially is manufactured

from materials of petroleum origin. In order to obtain satisfactory

asphalts, early refiners of this century required the use of special

crude sources containing residues yielding high quality asphalts

through simple distillation procedures. This limitation has

Largely been removed in recent years through more sophisticated

procedures employing selective solvent extraction or precipitation,

etc. The patent literature contains many references to the use of

special chemical treatments in attempts to modify asphalt character-

istics.(l) Large quantities of asphalt are made by air-blowing at

temperatures in the neighborhood of 500 700 OF.(4S)

The inherent characteristics of asphalt, together with its

relatively low cost, make it ideally suited for such wide-spread


- 1 -











applications as road building, roofing, w'atcrproofing and a multi-

tude of others. The comple:-x world in which we live todsy is

constantly demanding new and improved mAterials to meet the require-

ments of modern applications. Asphalt is recei.'ing a large sn:rc-

of the research stimulated by these der'nds.

A considerable amount of effort has been e:.pended tu improve

asphalt properties by blending or reaction in "situ" vitn other

materials, particularly polyreric substances, both natural and

synthetic.(4, 16, 33, 2, 7,67, 68, '., 9,) Since 1930, interest h23

been shown in the effect of the addition of small amounts of natural

rubber. I-calorub and Pulvatex were the firs- special rubber Additives

developed principally for this purpose Todsy interest in ruDber

additives for paving asphalt 13 very nigh.(101) A number of vinyl

compounds have been reacted rith asphalts in attempts to impart

better qualities.(60) Recently developed epo.xv resin formulations

in asphalts, having improved solvent and heat resistance, have been

used quite successfully to pave jet aircrAft riuna:,s and for pro-

tective coatings.(2, 3, 58)

Even though a large amount of effort has gone into the study

of asphalt systems, relatively little is yet known because of the

complexity of its structure. There has been recognition of distinct

constituent groups present such as asphaltous acids and arn-iydrides,

asphaltenes, asphaltic resins, petroleum resins, petroleum oils,

carbenes, carboids and inorganic material.(69) WMny attempts have

been made by previous investigators to characterize these groups as













completely as possible with the u2thods available This research has

been under-t.kerl to establish a better undcrstandirtg of the fundamental

aspect. affecting the runner in which v'inyl monomers will behave in

asphalt reaction s',stems. This study has been approacrned throuEg- an

anil.;is of factor affecting the kinetics or vinyl polymerization in

aspnaltic media. It is by correlation of the knowledge gained by

plreioLs investigators with the results obtained in this study, that

the object of tnis investigation has been, in part, achieved.











































....... ,. ..........














II. THEORY


A. Stabilized and/or Trapped Free Radicals
Are Present In ..sphaltc


Introduction

With the recent advent of techniques such as electron para-

ugr.etic resonance and nuclear magnetic resonance spectroscopy, a

considei-ble amount of effort his beenr focused on the study of

stabilized free radicals; an area that heretofore has suffered

from neglect. This neglect has stemmed mainly from the inability

to make suitable measurements for proper analysis Steacie in his

review of free radical mechanrusms uhich appeared prior to the

ability to apply these new techniques; contributed much to our under-

standing of active free radical processes, but did not present

information of the reactive character of stable free radicals, or

even of their widespread e:dstence.(90) Since the preparation of

the stable free radicals, pentaphenylcyclopentadien'l and 1,1-diplenyl-

2-picrythydrazyl, the ability of free radicals to remain dissociated

has been recognized.(52, 102)

Electron paramagnetic resonance absorption probably offers the

most direct means of evaluating free radical concentrations and the

effects of structural configurations. A striking feature of the

paramagnetic resonance spectra of stabilized free radicals is the

sharpness of the absorption exhibited.(28, 59) It is sufficient to



............-4-.
. .... ..... ..... ..... ..... ..... ..... ...... ..... ..... ... .. ..... .....





5 -





say at this point that there appears to be little doubt as to the

validity of the conclusions drawn, at least qualitatively from these

measurements. (28, 47, 51, 52, 59)

Since the early discovery of stablilzed free radicals, the

List of compounds wrich exist as free radicals, per se, which form

free radicals through dissociation in solution (in some cases strong

electrolytes), or which may yield stable free radicals through mild

oxidation with chemical or electrical means, has continued to grow.

Also, the evidence for the existence of trapped and/or stabilized

free radicals in many natural materials has continued to increase.

At cryogenic temperatures, experiments nave been devised to trap many

of the more reactive free radicals .(52)

Causes of Free Padical Stability

It is obvious that a more thorough understanding of the cause

of free radical stability is needed. Apparently, free radicals can

be trapped through what might appear to be mechanical means. Poly-

merizing systems in which the polymer precipitates have been shown to

occlude or otherwise trap free radicals.(53) For example, Bamford has

determined that a polymer of acrylonitrile prepared at 25 "C by

photopolymerization was found to have about 8 x 10-5 gn. mole radical

per liter. This represented about 13 percent of all radicals initiated

photochemically during the experiment.(13) In some materials such as

dicarboxylic acids, for example, free radicals appear to be trapped

by maintaining hydrogen bonds with the lattice molecules after

irradiation with x-rays or gamma-rays have produced them.(5)


mi ....... .ii .ii .i











Most of the free radicals which are obtained in pure forn or in

solution appear to be stabilized through what is normally termed

resonance.(52, 102)

It is convenient at this point to introduce the terms singlet,

triplet, and bi-radical to describe concepts which will be discussed

in slightly different context later in this work An olefin or con-

jugated double bond system is capable of existence in a state such

that all unsatur-tion electron pairs have the orbital spins paired

This is termed the singlet state, with only one possible conmination

of angular momentum vectors, because the electron spin vectors cancel.

A bi-radical is visualized as the situation arising when a pair of

unsaturation electrons' orbital spins become unpaired, and the

electrons become distributed so that they are predominately at

opposite ends of the previous olefin system. If these electrons ar-

not physically, widely separated, then the orbital spins which are

no longer paired can interact, giving rise to three possible com-

binations of the angular momentum vectors, with the so-called triplet

state resulting. Hence, the difference between a bi-radical and

triplet is one of degree. Rex.road and Gordy have illustrated these

phenomena with the compound, p,p-biphenylene-bis-diphenymnethyl. (73)

Chichibabin's Hydrocarbon




C = C C-

S Not:l diianagnetic state Bi-radical state
(singlet state) (triplet state)


- ...iS.iII.IIII.





- 7 -


The singlet, bi-radical and triplet states, are but a few of

the possible electronic configurations that can exist for molecules

that have complex systems of conjugated double Fonds, such as

condensed ring aromatic: hydrocarbon s:,stems. Indeed, r.ost of the

stable fr-e radicals which have teen cited in the recent literature

have as a part of their structure multiple phenyl groups. Tne

possibilities for resonance i: tnese types of compounds is evident.

Free Radlcal Types Expected In Asphalts

The evidence for the existence of hijgly .'oraplicated aroimtic

structures; and in addition, structures contcinin& nitrogen, oxygen

and sulfur, is abunaant for asphalts This seems to be particularly

true for the nigher molecular weigni fractions such as tne asphaltcnes.

(.3L, "6, 95, 105)

Perinapntnslene, whose structure is sho'W, belov yields free

r-dicals in a very interesting mannrer.(89)
..H H A H

H1 rr I -CCl r\ + H

H H
Perinaphthalene Perinaphthnlene
Radical

In carbon tetrachloride solutions, the central hydrogen atom is

removed leaving an unsatisfied valence at this carbon atom.

These conclusions uere reached by examination of the fine line

splitting of the electron paramagnetic resonance spectra. This

solution also becomes highly colored upon standing. This type of

compound is almost certain to exist in asphalt systems,





- 8 -


particularly the high molecular we'iht. portion.(29, 31, 105)

Aromxtic free radicals can be produced in solution by the dis-

sociation of structures which are not tightly bound. An e:amprlc of

this is the dibenzoyi tetrazanes, whose generic structure is as

follows: R R


O=C r=o\


R" R"

1,1,4, h-te t re.-p- ~'kyI phenryl-2-
3-alPyldibenzoyl tetrazanes

The dissociation occurs between the central two nitrogen atoms,

yielding a compound of the hydrazyl type.(87) It maj be possible

that analogous structures, capable of dissociating into fr.-e radicals,

exist in asphalts. This has not been demonstrated to tre knowledge

of the author to date. Although no direct reference has been made

to condensed ring aromatic compounds, otler than perinaphtbalene, a

large number of condensed ring aromatic systems have been demon-

strated to yield stable free radicals.(52)

Natural and Manufactured Materials Hav-ing Stable Free Radicals

The spectra of a large group of pyrolytic carbons, as deter-

mined by electron spin resonance (ESR), have been examined by

numerous investigators. With this group of pyrolytic carbons, the

high molecular weight constituents of petroleum, its residues, and

other similar naturally occurring bitumens, including those derived

from coal, shall also be discussed.











These materials generally e-nibit sharp ESR absorption bands.

Estimates of tne free radical content of materials representative

of this group of pyrolytic carbons has been collected in Table 1.

From the data collected in Table 1, it may be seen that

stabilized trapped free radicals are, indeed, characteristic of

pyrolytic carbons produced either naturally or artificially. It is

clear from these data that the content of free radicals is a

function of the thermal history and total carbon content. Pyrolytic

carbons formed slightly below 6C0 C. give the stronger ESR

absorption. X-ray examination has shown tnat it is at the point of

pronounced free radical content thst the formation of condensed ring

clusters bcgin; both with regard to the variation in formation

temperature and carbon content.(12) Investigations by Austen, Ingram

and Tapley have led them to suggest that:

"The essential mechanism in the trapping and stabilization
of unpaired electrons [in the complex carbons being dis-
cussed7 is the existence of ring clusters containing more
than a certain number of carbon atoms. Such ring clusters
will possess a high degree of resonance energy available
for stabilization of the electrons. . The decrease in
radical concentration above the 90 percent carbon content
or 550 C. carbonizing temperature is explained by the
gradual formation of graphitic sheets, the individual
carbon clusters joining and thus saturating their broken
edge bonds."

In the above hypothesis, it was assumed that the radicals have been

formed by the breakage of bonds around the edge of carbon clusters.

It was also pointed out that some radicals may occur in packing de-

fects producing internal trivalent carbon atoms. The ideas proposed

by Austen, et al., have been generally agreed upon by other working

in the field.


. i....... ... ..




i= .....- 10 -


TABLE 1, FREE RADICALS STABILIZED II FYROLYTIC CARBONS


Radical
Content,
Spins/nm.
x 10-10


Material Source


Treatment
Temp.,
OC.


Weight
Ratio
C/H


Coal Products

A Pittsburgh Coal
Coal Vitrain
Coal Hydrogenation Asphaltene
SIn CSg Solution)
In Dioxane Solution)
miscellaneous Coals
Miscellaneous Coles
Miscellaneous Coals

Hydrocarbon Chars(a)

Dextrose Clar (in vacuo)

DarZuae Char
Itatree Char
Dextroase Char
CWxhia1rosae Char
wotleum. Reidue Char


14 5 C 0)
15.3 (o)
14.0 40o)



8w*C) 12)
94%C) 12)


(12, 17, 71, 96)


12
12

12
12)
12)
12)
32)


500
1200
1000-1700 (b)


56)
56)
(56
S56
52


1 8 10.9 (44)

20-30 9-10 30)
0.5-1.0 7.6-8.2 30)
ail 6.0-6.2 (30)
q.' iUW i si, IAeBllly that any charred
3l4til'^iiw 6aOe., give5 s streg ESSR

f'MMBr kAin aMiolar to Oat of
:MiE, .S t : e 'I!1t'm P g


References





- 1 -


An interpretation of the bond breakage at the edge of the con-

densed carbon rings by Ingr=m, is that the electron released by the

bond breakage is stabilized by the large amount of resonance

associated with aromatic rings, and as a result, nove in highly de-

localized r -orbitals over the system. The presence of such de-

localized radicals has been suggested to be the cause of carbon blacks

actively participating in the reinforcement of rubber.(52)

Petroleum products have been placed in the category with pyro-

lytic carbons because of the analogy that can be drawn between their

probable origins and similar constitutions.(35) In an inter-sting

paper by Yen, Erdman and Pollack, it was determined that the charac-

teristic X-ray diffraction of the high molecular petroleum fraction

(asphaltenes) from nany. crudes could be reproduced by blending

samples of polyethylene and carbon blacks. Also the X-ray diffraction

pattern of the aromatic portion of these asphaltenes compares with

that of a blend of condensed aromatic compounds of known structure.

Figure 1 is a model constructed from the data they obtained.(105)

The analogy to pyrolytic carbons from other sources seems very

plausible.

The paramagnetic resonance of crude oils is apparently con-

centrated in the high molecular weight colloidal portion. This

portion has been labled "asphaltenes" from a comparison of these

materials with the so-called asphaltenes obtained freomasphalts by

precipitation with light paraffin hydrocarbon solvents. Outowaky,

ot al., observed that the ESR absorption of a crude oil ik pear












I,
3-d o

L U VCi 43
..

*L h Q'0 U
43 -i .- 0I
I I
u


iS! -.


Cl) n

ac,


4^+*
O ^


II
S


"0

9-


p.0

SU
C.
0 I



4.



-r rt-1
t4
IC
Cr,


c< 0






C



V;


~


...ilhti











after extensive centrifigation at 80,000 G's.(25, 44) Some concern

has b.-cn expressed as to the possibility of the pwarsmiTnetic resonance

of petroleum stemzu;inU firon other than frne radical sources. Vanazdium

in the +4 valence state as vanr dyl readily forC s chelate compounds

which exist frequently in nature as porpnyrins.(T0) T.is -iny be

true for other metals as well, and therefore, the possibility of LSR

absorption from this source should not be overlooked. Eldib, Dunninc

and Bolen, in a study of the colloidal rr.terials in petroleum,

obtained by ultracentrifugation, nave determined that vanadiur. and

rickel are present in this colloidal material in concentrations less

than 25 and 8 p.p.m. respectively. (34) These uere the only ettals

detcnmined to be present in appreciable concentration. O'Reilly has

compared the ESR spectrum of a solid asphaltene %ritl that of vanadyl

etioporphyrin I (VEPI) dissolved in a high viscosity petroleum oil.

The spectra of both samples showed the same general characteristics.

The ESR absorption demonstrated by the porphyriuns present in the

solid asphaltenes however, is quite small compared to the band

attributable to free radicale.(70) Only about 0.1 of the spin con-

centration observed, as determined by elemental analysis for nickel

and vanadium, was attributable to these materials in asphaltenes

investigated by Gutovskys, et al.(44)

In addition to the evidence cited for the presence of free

radicals in asphalt, that has been essentially based upon measure-

mcnts made by ESR; Poindexter has observed the Overhauser Effect

in asphalt solutions. The details will not be discussed here,





- 14 -


However, it can be said that the contribution to proton relaxation

from the asphalt is a linear function of asphalt concentration.

This contribution to proton relaxation arises through the interaction

of the electron spins of the free radicals with the nuclear spin of

the hydrogen atoms present.(Y5) It mws stated tnat there was no in-

dication of any unusual quality of the asphalt radicals observed.

Saraceno and Coggeshall conclude from their measurements, that

the fire radical species in petroleum oils are stable, and are not

created through dissociation of diamagnetic molecules upon dilution

with solvents.(83) Tnis is consistent with the linear contribution

to proton relaxation with change in concentration as mentioned above.

This however, is in contrast to the results reported for coal hydro-

genation asphaltenes; see Table 1. Ho effects on the free radical

concentration were observed to be a function of either sunlight,

ultraviolet light or bubbling molecular oxgen into a petroleum oil.

B. Principles Underlying Free Radical
Induced Polymerization


That there are polymerization processes which are induced by

the presence of free radicals does not seem to be in dispute.(14, 20,

26, 39, 77, 99) The strongest evidence for this appears to be that

acceleration of polymerization rates of man;, vinyl compounds occurs

in the presence of substances which are known to give free radicals

upon thermal decomposition, after exposure to ultraviolet light, or

bombardment from radioactive sources. In some cases, polymerization

has been known to occur in the absence of light or free radical










forming materials. Tnis naz become known a- tnermal polymeriza-
tion, but can still be explained on the basis of a mechanism
rich proceeds through the action of free r-ailcals, once polymeri-

zation is initiated. These free rid-cals have generally been

considered to be quite reactive, in that their life time is rela-
tively short.

Attempts to correlate the kinetics of some of the more simple

systems have been reasorLnbly successful A very good review of

this subject has been given by Bamford and Barb (14) It appears
tiat the cuse of homogeneous solution polymeri-ation, is the

simplest to treat kinetically, particularly at relatively low

concentrations of nonomer. Several simplifying assumptions have

usually been introduced by various authors, in the derivation of

correlation equations. The main justification of these assumptions,

of course, lies in the fact that they yield correlations which are
experimentally true.

The overall polyueri-ation may be described in terms of
three phases which are distinct conceptually.(14, 37) These

phases are initiation, propagation (in some treatments which

chain transfer) and termination. During the initiation phase,
several methods of opening an initial double bond have been dis-

cussed. During thermal polymerization, the assumption has often
been made that a bi-molecular reaction between monomer molecules

yields active free radicals. When an active free radical is

formed through the action of radiation, bombardment by high
..... iiiiiiiiii i




- 16 -


velocity particles or ther al decomposition of an unstable compound,

initiation is usually assumed to occur through a bi-molecular reac-

tion with the radical forced, and a monomer atom. During the propa-

gation phase, the active free Irdizals previously formed ad.d to the

double bond of the styrene molecules in a chain fashion, with the

rate of each new addition being governed by a bi-molecular reaction

between the previously formed active free radical, and tne new mono-

mer molecule. Since each of the steps in this chain reaction

occurs between molecular species which are very much alike chemically,

even though different from one another in the abLolute sense, the

rate constant for each of the propagation steps is assumed to be

identical. During the final or termination phase, the assumption

is made that termination occurs through d icproportionation and combi-

nation between any tro of the existing active free radical species.

A fairly subtle effect which merits our attention is that of

chain transfer with the solvent, polymer, and monomer molecules.

This occurs when an active polymer radical abstracts a hydrogen atom

or other atom from one of these molecules to satisfy its unsaturated

valence, leaving the molecule which was attacked a free radical.

If this newly formed free radical is sufficiently reactive, the

effect on the overall rate of polymerization will be slight, since

the propagation of the oonomer reaction by this radical continues

more or less uninterruptedly. Breitenbach and aschin, also Mayo,

have effectively shown this to occur when using carbon tetrachloride,

a solvent ideally suited for chain transfer. By assay for chlorine











in the resultirG polyimr, it vas found that approximately four chlorine

atoms per poly:rmr molecule were incorporated, and that the effect on

the overall polylernZ ation rate was onl;, slight. The najor effect

noted for this process is a substantial decrease in the polymr molec-

ular oeight.(22, 62)

Some solvents may have a retarding effect on the polyraorizntion

rate through the action of chain transfer. This has been e::plainod

by Price and Durham on the basis of formation of stabilized solvent

free radicals with, insufficient reactivity to propagate continued

polym.er grrrth.(76, 93) Of the solvents studied, nitroben2cne,

pht nols and 2,i-dinitrochlorobe;izene ha'e been shown to have a

pronounced retarding effect. In some instances as hiChl an one dini-

trochlorophenyl group per polymer cnain uas found dhen polymerization

was conducted in this solvent. In each of these cases the possibil-

ities for resonance stabilization of the free radicals is apparent.

A concept which is useful in the development of kinetic rela-

tions is the so-called "steadjy state".(l4, 41, 90) The steady

state condition can be visualized as a condition in vhich the rate

of formation and removal of certain reactive species arc approximately

the same, so that a seeming equilibrium situation is manifest. Even

thour. this is only an approximation to what is actually occurring

*very useful relations have been developed uben the magnitude of the

error introduced is small. In polymer kinetics, the assumption of

'steady state" Generally implies that the concentrations of the

free radicals, intermediate to the polymerization process, attain


.::::::::..i .i




,- 18 -


equilibrium values. From this it follows that tihi rate of change

of a given free radical specie, with time, is nearly zero.

A Theoretical Equation for Thermal Polymerization

An example use of the principles cited is the treatment of the

thermal polymerization of styrene in solution.(lL) Experimentally,

it has been shown that styrene (when quite pure) has a solution

polyn rization rate which is second order in terms of monomer

concentration, if the reaction is not carried on to too great an

extent.(6, 14, 20, 27, L3, 45, 97) This, houe.er is not the case

when polymerization proceeds in bulk, i.e., pure styrene alone.

When the effect of change in the activity is accounted for, the

polymerization rate is second order in terms of monomer activity.

Walling, Briggs and Mayo measured the vapor pressures above various

solutions of styrene and polystyrene to obtain the data required for

this refinement.(97)

Bamford and Barb, in their review of polymerization processes,

have presented the following mechanism for the thermal polymeriza-

tion of styrene.

The Assumed Kinetic mechanisms m for Thermal Pol'yerization

Associated
Equations Governing Rate Rate Constant

The Initiation Phase

(1) M + ----- 2Rc* kc

(2) + M ------ R1* kpc

The Propagation Phase

(3) R* + M ---- R* k


" a:




- 19 -


R2* +

R3 +


-- R,

--


(6) Rn-l*+ ---

The Termination Phase

With Active Free Radicals

(7) R + Ra*----

W\he r .


kp2
kp3





kp(n-l)


Dead Polymer


rI Monomer
R* Free radical
k Rate constants identified by
the proper subscripts
1,2,3, ..,n,n-l denotes the number
of monomer units affixed
c Denotes a radical formed in the
Initiation phase
s Denotes a stabilized free radical
a Denotes all active free radicals


If the polymer chain length is relatively great, the overall

rate will be governed by the rate of monomer reacting in the propo-

gation steps to a fair approximation. From the preceding statement

of the assumed mechanism it can be shown that the overall rate of

polymerization may be expressed analytically as:

i=n
-d(M)/dT =k P(R *)A + k kpi(Hi*)M


Utilizing the assumption that the kp's are identical.,Lnd notf.i

that,







.. .==S


Rn




- 320 -


i = n
1=n
R-* = Re* + Ri* by definition, 2
i = 1

gives,

-l(!l)/dT = kp(Ra*)1 3.

The rate of change of concentration of any free radical species

may be stated in general as:

Fate of Formation Rate Propagation Rate Termination Rate
Change of Species R1* to Species Pil* of Species FRi

For purposes of clarity, it is shown in Table 2 through the use

of material balances derived from the preceding cmchanism, how these

relations may be solved to obtain an equation explicit in R *. Com-

bining equation 7 from Table 2 and equation 3 yields the overall rate

in terms of H.


-d()/dT =k.p (2k/ / ta- ..

The correlation thus obtained predicts that the thermal polymer-

ization of styrene should be second order in terms of monomer concen-

tration. To be completely rigorous, this entire analysis should have

been made on the basis of thermodynamic activity, as indicated previous-

ly, when it was stated that a correction for this must be applied in

bulk polymerization. However, in dilute solution, say 10 percent

monomer or less, the concentration expressed in units proportional to

the number of molecules per unit volume should adequately approximate

the activity. If the density does not change appreciably as polynmer-

ization proceeds in this dilute solution, a further approximation -an

be made; i.e., the concentration expressed in weight percent will very

nearly be proportional to the concentration expressed as above.



h......






- 71 -


r-1 (C4 r'1 -4
r~- t


a
's






g L
0



(U C..ri
'CO
-rr




rt ?
e- .-





~C.




c r
s











( L
o







'14G
t_ ,-





















"F C
-

.r.. Da n
I C cl]

















r:cm a
* .4 - .




'4 e. 4-









r re CA
*^ I ^

















C .. II
i 0. -
124~ "L

I* 4









cfl ?- >f)
r4
j^. 4 i --
I C 1q-4
i- 0 4(41






I iL .T)
4-. I I--
r-4 T f *l
I TO(UC -

C ,i .4.



-4 l-i








*un
44 (4
11 .c 01 PN.'

-c'- c
TC t441C ^
(:0.1 U.

$3 rC.41
r 1T-. vi 11

^' (-, 1 1

4o < ( '
04-1-


In '
ar-r


1ll'
*- c
1 I .4
4-'O *--
+ J (t'


6 I- L

.C. L

-C
.4b 14 Ii

(41 .c
S +. *1
c4 4-.






'-4 i'4 I'j
c;. .-
- E i-
.-1 r




I' 1 ;L
; 1 1
.C- C Cl 1-.
l'-4 '14 <



' L. 4. C-




44 C C
.4-I 0 -
r. 43 .-









i L
0) C-. LU












C .
G. -o I
-H4.-. r





f~ ri 1


44 (N












8 lo .ah
(1 -r C
Itl . I^

-a 4

4- 411









.C .c -
44 .4- (439

C, r- *


C.'

C.HJ GB








o *
64 (1 -. ; in


+*


*ri Gd 0
0-ri


( 11
'-4


ji.......................










Integration of the rate equation allows it to be shown that a plot

of reciprocal monomer concentration versus time should yield a

straight line whose slope is the overall rate constant. The details

of this are shown on page 59.

C. The Influence of Stabilized Free Padicals


Previous discussion has pointed out that stabilized free radical

and/or trapped free radicals are demonstrably present irn U. types

of materials being studied. Several investigators have noted catalytic

and inhibiting effects in natural materials whicr are analogous to

these materials under consideration.

Very recently Wright has made a careful study of the inhibiting

effects Of a number of pure synthetic stable free radicals and several

natural materials containing free radicals (104) During the polymeri-

zation of styrene catalyzed by bcnzoyl peroxide, it was found that tlhe

stable free radicals, l,l-diphenyl-2-picryl.hydrazyl and Banfield's

free radical (which is prepared from Banfield's hydroxide (18) ),

exhibit an inhibiting effect which increased with increasing concen-

tration. The same effect was observed for the asphaltene fraction

of gilsonite and a Wilmington crude oil.(104)

Heexaphenylethane, when in solution, has been shown to dissociate

into the triphenylmethyl radical.(214, 102) Mayo and Gregg, in a study

of styrene polymerization, used hexapbenylethane over a considerable

concentration range.(61) From material balance calculations based

on the polyipr molecular weight and the extent of reaction, they

estlaBte that about 77 molecules of hexaphenylethano disappear for
====- e
----,i;











each molecule of polystyrene that would have been formed in its ab-

sence. This work lead to the following conclusion:

"Any free radical may start or terminate the polynerization
of a styrene chain. Whether a source of free radicals will
behave as a catalyst or an inhibitor depends on the balance
between the rate of addition of these radicals to monomers,
the rate of interaction of radicals and the rate of growth
of the polyner radicals at the chosen temperature. If the
radicals do not add rapidly or if they are supplied too fast,
then a high radical concentration results and chain growth
is restricted. If the radicals add very rapidly, or are
supplied slowl; enough, polymerization will result. These
statements mean simply that the dividing line between cata-
lysts and inhibitors is not clear-cut; the differences between
them are quantitative rather than qualitative."

Symons has studied the interaction between acrylonitrile and

amorphous carbons and has found that o:.ygen-free carbons initiate

polymerization in the dark.(91) With no carbon present, thermal poly-

merization did not occur at the temperature used, 600C. Activation of

the carbons at 000C.-5500C. over moist air causes the initiation

effect to be destroyed. This was explained on the basis of the forma-

tion of surface quinone groups which act as inhibitors. It was suggest-

ed by this author that two types of free radicals, i.e., trapped free

radicals and resonance stabilized free radicals may be the active

initiator. Also, the possibility of mechanically isolating some of

these free radicals from the polymerization process may occur.

Breitenbach and Preuesler aVarently confirm the work of Syms re-

garding the inhibiting effect of activated carbons by their ,tudy

in styrena polymrization. (3) Boiever, the inhibiting effect on

styrene which does have a definite theraml polneyrizatioa rate

lasted for only a limited time after which polymeriatim ocacumed at

at least the naeaal rate. Thi is : corAistent with the .eiiomt -i




- 24 -


inhibition by surface quinone groups since it is known that the effect

of inhibition by quinones is gradually lessened through free radical

reactions with quinones to give non-reactive by-products.(14, 61)

Kraus, Gruver and Rollmann studied the effect of carbon blacks

on the free radical thermal polymeri2tion of styrene at 50 oC.(55)

These carbon blacks were treated in the following ways: a) reduction

over platinum with hydrogen or by sodium borohydride, b) heat treatment

at 1000 2000 C., c) and outgassing at 300 oC. under vacuum. Each

of these carbons causes a substantial induction period to occur.

(ote: The pure styrene used gave no induction period.) After the

induction period, acceleration of up to five times the normal polymer-

ization rate was obtained. Hydrogenation, presumably of the surface

quinone groups present in carbon blacks, drastically reduced the

l r th of the induction periods observed, but caused no measurable

change in the acceleration effect. High temperature beat treatment

destroyed both the induction period and acceleration effect. This is

in accord with the known phenaemean that high temperature heat treat-

ent causes graphitization of carbon blacks by allovLng structural

Iavri Vgemnts that destroy stabilized free radicals.(12, 17)

Outgassing of adsorbed oxygen caused no observable changes. Free

a Sia. coaeentration in these carbon blacks was measured before and

after polyflrtzation. Little, if any, change in concentration

(tch.o:,ii,.of the order of 10*18 unpaired spins per gram) occurred.

.."his apparently negativee observation prohibits it being stated

ae lusitBvy that free radicals are the cause of the acceleration


. a m.............





- 25 -


observed. The possibility of this effect being produced by surface

peroxide formation, however, must probably be discarded, since the

thermal history with treatments up to 300 OC. had no effect.

Consideration of the ability of charcoal and other pyrolytic

carbons, as well as paraagnetic substances such as free radicals,

to catalyze the conversion of para-hydrogen to orth--hydregen pofmts

out the ability of these stabilized free radicals to interact with

other systems.(82, 90)

Hulbert, et al. have considered a theoretical mechanism of

vinyl polymerization from the view point of the electronic states

of olefins, particularly ethylene. Their calculations indicate that

ten of the twelve valence electrons in ethylene are localized by

pairs taking up positions between the carbon and hydrogen nuclei.

The remaining two electrons which are essentially distributed over

the entire molecule, have been given the name "unsaturation electrons".

(50) In the lowest energy state, these two electrons are in the same

bonding orbital "N" and by the Pauli exclusion principle must then

have antiparallel spine. Since these electron spin vectors cascel,

there is only one possible combination of angular mwe ntum vectors,

and the so-called singlet state is the result. It is pointed out

that promotiar of an electron frex the bonding orbital to f aon-boitt

orbital should be rare in the absence of an external anpsiwic tibia,

because of the necessary unaouplpg of the W'gi via eachen n a

Wa.m tic energy, :aen though ufltleient easWy-yw be sBOnlable in

the molecule itself. Whainver an "oad electron na6e1cal', i.e., a

free radical, cmr within the kinetic theeay rqdiuB, ti.iiunagjiU 1
.... ...... O




- 26 -


becemes more probable. The result of this uncoupling is the triplet

state in which the electron spins are parallel. When parallel the

spins are uipaired, in other words, what is commonly termed a

diradical has resulted. This diradical may or may not have bonded

with the free radical which aided in the uncoupling of the electron

spine. Active diradicals once formed have been reported to be

capable of propagating a chain reaction from each free radical site

in the molecule.(li, 20, 26) It is not known whether cr not the

stabilized free radical will form a bond during the uncoupling

process; however, even if the bond is formed monmntarily, subsequent

dissociation of this bond might occur. This possible dissociation

of, or failure to form a bond could possibly account for the failure

by Kraus, et al., as previously mentioned, to observe a change in

thi total concentration of unpaired spins before and after polymer-

iBation.

The total experience gained by the various investigators cited

tintd to igbicate the plausibility of an acceleration effect caused

by the interaction of stabilized free radicals with vinyl monomers.

Tie ability of stabilized free radicals to remain dissociated over

lA:. perteds of time does not neassarily imply that they are

ia~ambtly unreactive. For exaepl, dipbenylpicrylhydrazyl is known

to retst with u:6e reactive free radicals even though alone it

.ieP disaoeiated for long periasl of time. From the ability of

styrene to urMrgo thermal polyjerilation, it is clear that formation

o0' Sat. free radicals iS paeetble even in the absence of catalytic





27E -




substances. The assumption of the initiation of styrene polymeriza-

tion through a bi-molecular collision of styrene moleucles has

successfully correlated the kinetics of the thermal polymerization

of styrene, it may be recalled.

fealizing that even a slight increase in the probability of

forming the diradical state of styrene would increase the overall

polymerization rate, and that a stabilized free radical can poten-

tially increase this probability, leads one to the following specu-

lation: may not the presence of a stabilize& free radical, near a

monomer molecule, at the time of interaction with a thlrd wolecule

(which possesses a definite probability for reacting), increase this

probability through the mechanism described by Hfulbe-,t', An

alternative question -Is-, may there perha-ps be irsufficienIt energy

normally available for the stabilized free radicals prouent in

aphalts to react alone with L monomer or active frae z-Ldical

Molecule?

A TonAclEL~to o oyrzto rfunc ySaiie
Free Radicals

A nechaniam -wbich embodies thbe anE;umptiorw and principles

utilizeid previously for the derivation of a rate equatid% correla-

ting the tlienws polymorizatien, bas been develOP'ed for poly1**riZa-

tiom influencL-d by the pmesence. of stabilized free rwdicala In

addition to the ezssumptions opoa Previously, it hac a140 bien

Assumed that (1) during, the intiation rbatt, the ftorm-ti96 of mctlve

frEe radioils vey occur thrmoig a. tor-oleculax reftttiom involIvia

the wtabt31Zd free radcual WVd two WWWma moleCU34a aot (2) during




- 28 -


the termination phase, reaction ceases through a ter-molecular

reaction involving an active free radical, a stabilized free radical

and a monomer molecule. The assumed mechanism follows.

Tne Assumed Kinetic Mechanism for Polymerization Influenced by Stable
Free Radicals

Associated
Equations G verning Rate Rate Constant

The Initiation Phase

(1) + M ---- 2R* k

(2) Rs* + + M ---- M + Re ks()

(3) Re* + -- R" kpc

The Propagation Phase

(4) R1* + M ---- R2* kpl

(5) R2* + 1 --- R- R: p2

(6) R3* + --- R* h3





(7) n-1* + M ---- kp(n-1)

The Termination Phase

With active free radicals

(8) Rn* + R ---- Dead Polymer kta

With stabilized free radicals

(9) R* + Rs* + M ---- Dead Polymer kts
(a) Me cAnfaet~A tian dependence of the rate in this step is assumed to
be sia-linMr d: Rg*. Therefore, the forward rate equation for this
step:. i arbit arily written as. 2
(Rc*/farbard = k, *) (M)
TI eaFSaBrt D ji..,been introduced to represent a simple noa-linear
function.


a S





- 29 -


For purposes of clarity, it is shown in Table 3 through the use of

material balances derived from the preceding mechanism how these rela-

tions may be solved to obtain an equation explicit in Ra*. Coa ining

equation 7, Table 3 with equation 3 previously shown in the discussion

of thermal polymerization for the overall rate in terms of Ra* and M

yields:

-d(M)/dT = Ipkts/2ktas 5.

S 2 4k ta D .] 2
(Re*) + (2kc + ks (RA) )) R M
ts

Setting the term in front of H2 equal to K yields an overall rate

constant that is analogous to that obtained for the theril polymeriza-

tion process, in that it is a correlation constant for an equation

second order in mononmer concentration.

The overall rate constant, K, is therefore, actually a function

of the part jeter Rs*. This of course means that K will not be a

constant unless the concentration of RH* remains essentially constant

during a given polymerization run. This will be approxdnately true

for polymerization that represents a small quantity of S leer poly-

merized As before, the rate equation may then be integrated to show

that a plot of reciprocal concentration versus time yields a strain t-

line curve whose slope is the rate constant K. At a 4HPlBitftfi

of HR* 0, the rate comaiet, K, obvtissiy MWiuiU llb* l *fl k

thereal polymerization rate ceauSit.
....................::: :::::::
It is believed that the preseeiC Ailscemain cM .

reassoabtle justificatima fbr the 1a1Aiu H that hg .wiiBWi||[ J.gg At
'iiiiE: iiiiiiiiiiiii





-i 30 -


-. -





II 3 I II I
C' CD ul D'







-Y. I16
* P-1 +W.






4/-. *I S 4 --







.N I.
O a 4 11



*a *

N N- P'





























*"'""""""" E-. 0- F
4--p


m *-H co
~L..
0cr










o C. w

C' ..
S.-, IA C *, -

L- L 0-- ,







-4J C .*



Ir c r- c
C -I -l C


















* .1 0.-, *
C_ P
04 Cn C 4)3 3




IL cc L .; Z
450 0 Thl U


r-I .' np v r
N Z i J rI

a Cr 1 -1 t4- r 0
4 v C C iGt -,


Y cF CZ -
I C iT + O C H

4P91 + m 45%Li*
H A: W c

4 0+)45
'-1 +21B N -r^l.D ui


16n 93 + 30 0' 4C

a Ct.fl
C Di 0 C N


n .!r 4t 0j "-
4 5 + TCJ .
U CLIi n













0] 05*2b(
IC 10 ~rO


..i .... a::




31 -


this point, the theoretical development of a rate equation has been

completed which correlates the variation in monomer and stabilized

free radical concentrations.










































.I.













III. EXPERDMENAL


A. Materials Used


Petroleum Residues

The four asphaltic residues used in this investigation vere

supplied through the courtesy of the Texas Company. These residues

represent different types of asphalt sources that yield products

having different properties. Of these asphalts, several were

selected for modification by the processes of air-blowing and

selective solvent removal of the asphaltene fraction.

The air-blown asphalt (R60-11) was prepared by bubbling air

through a 5 kilogram batch of the Gulf Coast haphthenic Residuum

(ii19) for a period of li hours at 500 5 OF. in a stainless steel

heated ai vented vessel.

The asphaltene free asphalts were prepared from the filtrates,

debcribed in the following section discussing asphaltene prepara-

Sisp, by stripping the solvent (n-pentame) to a final temperature

qf 'bout 350 O at 1 em. Hg absolute pressure.

The properties which have been determined for these materials

a presenedA in Table 4.



isUe, a product of Chesebrough-Pbads, Inc., obtained from

*S Iqil phtbacetical supplier was used.


-32-













(N C
r-l
- -4


r-I

r-l


.9 .4 E


i- r




E li





tt
a;














M7C


di n




















11 .* 4
ca F -
dr- g
_li r' a





1-1 1-


r^,- .








ad





4 S -l
.-i o'






0


43 4
'3-i di
o a

0 0
o 0











C O
o o
a a











o
-I- r.



CD 14
o .,-F,~
C'- '3)

'I P*
a -H:
v 2
91. U.;


P--

v-I


43 4)

f-I I-

a


C
*^ 'ge C)


O 0Cj r a 0"


OC-'l


.Ll
-, 1. 1- '-I e





0'




















cc
o5







Sr
-

























P
di













ni














44 en
Gli





CD

ar


r-1 .-E







en)






(34B) 9 O


a-A s 4
hOC)
^co nnr- I
o.^j +0.4


- 33 -


rj


cs- io
0


y3 .



r- o-.
'-


ir. rN

1 *
0


Hi





he
oi

rO


. r



c ( e
'v-I


a


.ii




- 34 -


Petrole-a AsMt lteses

The asphaltenes were prepared froa the stock indicated by the

following procedure:

a) Stake a mLture of the petroleum residue and n-pentane

(1:1 weight ratio) until the solution is judged to be

haememeeus. This was actually accomplished by allowing

several days Idxing in a bottle supported on moving

rollers.

b) Dilate a portion of this mixture to give a final solvent

to asphalt weight ratio of 20:1 in one-gallon batches.

c) Filter the solution on a large dense filter paper, retain-

ing the filtrate adn filtered material.

d) All the filtered material to dry, free of pentane, by

reading the filter paper out flat, exposed to the air.

e) Callime the filtrate with previous portions obtained

for future stripping of the solvent under vacuum conditions.

I 5ttglMt was r.Ae to wauh the asphaltenee thus obtained free of

"u "iii Wiotaas, since the purpose here is to obtain a large

qlity of the .asphaltser fraction from each material rather than

tl taiii u a strictly quantitative separation as is possible In one

a:? theb ,,iansaadized ~aasytical procedures.

O .aW a aHi, the results of a series of deterBinatimau based

i aliC r qisi ts" ofr IattriaJl for the asphalt 5119. It can be

*ii lai ~l'tuthis figure that at a solvent to asphalt ratio of 20 ml.

.......l e i'pei. . ashalt, a definitely larl decrease in the yield


..... S...i.. I


I~II al' E~iiii





- 35 -


10









.I.





SBreak Point
-4-




IrI

o I I

I I These determinations made on
2 I
- the Gulf Coast Naphthenic
II
SResiduum, S 119.


0 I I-- I I I
0 20 O0 60 80 100

Solvent Ratio, ML. n-pentane Per Gn. Asphalt

Figure 2, The influence of solvent ratio on the yield
of petroleum asphaltenes.














a...........











of asphaltenes occurs. For this reason, the ratio of 20:1 on a weight

basis, which is obviously somewhat greater than the above value, was

used in the asphaltene preparative procedure, as a compromise between

the loss of quantitativeness in yield and the necessity of handling

extremely large quantities of solution.

Mnaomers

The monmers used were obtained from the Borden Chemical Company,

Honpmer-Polymer laboratories at intervals to assure that fresh

materials were being used. Generally, the inhibitor hydroquinonee)

was removed by washing twice with two percent aCHB solution and

rinsing thrice with distilled water to a neutral point indicated by

phenolphthalein indicator. Drying and removal of trace polar mater-

ials (oxygenated impurities, etc.) is accomplished by percolation

through a column containing a section of granulated calcium chloride

aSd 80-200 mesh activated alumina.

To determine if additional purification of the moomer by

di&tillation would change the thermal polymerization rates, simple

vacuum adstillations at 120 OF. and 1 ca. Hg absolute pressure, using

a ii...fied vigreaux column, were twice performed on a styrene sample.

:iio change .sa: ..observable.

:iThie mo rs used have been styrene, vinyl-2-ethylbexanoate and

oA vinyinaphthimiJne

II 'viy'prhe t&l aAonn of polymer from the styBree used, with anhydrous

aiiitiimel, .it :was Jdsa that less than 0.5 percent polymer was present.


__


- 36 -




- 37 -


Laboratory Reagents

In all cases, coamercially obtainable reagent grade chemicals have

been used. It is considered that the following materials warrant

special consideration:

a) Xy/lene (mixed o, p, and m isomers) was found to be only

suitable in the best grade (Baker's White Label Analyzed

Reagent) obtainable, because of the presence of trace

quantities of materials which are slowly hydrogenatable

in the inferior grades.

b) The palladium hydrogenation catalyst, Grade 937, was

furnished by the Davison Chemical Company, Baltimore,

Maryland. This catalyst comprises 5 percent palladium

on a carbon support.

c) The methyl alcohol used in determination of polystyrene

was supplied anhydrous in one-pint, sealed bottles to

assure that the presence of water was minimized.

d) Adsorption alumina, 80-200 mesh, was purchased from

Fisher Scientific Ca pany.

B. Apparatus Description and Operation


Polymerization Equipment Description

Reactions of asphaltic aqd eammaeric materialss are catnitted

in a sealed autoclave which rocks to agitate the reactants. This

type of apparatus provides a mmans of reactltd in the dark, i.e.,

the effect of the catalytic action of light is eliaiated. Thtls

reactor is equipped with a temperature controller ( 12 a-d




.... .....





- 38 -


recorder which allows reactions to be conducted over long periods

of time with a minimum of personal attention necessary from the

operator; however, this should not to construed to indicate that

neglect may be permitted. The apparatus is shown in Figure 3. It

may be noted that a nitrogen cylinder equipped with pressure

reducer is used to maintain pressure on the system. A list of the

principal equipment follows:

1) American Instrument Coapany super atmospheric

pressure rocking autoclave, -23/'8 inch series,

equipped with 3 liter and 1.5 liter bombs.

2) Brown Pulse Pyrovane temperature controller,

0-800 OF. range, Model No. 105C4PS-25, Serial

No. 700196.

3) Bristol Company temperature recorder,

0-1000 OF. range, Model No. 12PG560-21, Serial

ao. 561908.

Auxiliary equipment is provided which allows introduction of onomer

and rae al of reaction sales whenever desired. Measurement and

Ciltrol of temperature is obtained by means of two thermocouples

is~eted into':a nll provided in the center of the autoclave. A

cakll water-cooled heat exchanger is provided on the outlet line

to. coolmii. i ap3!iii: Ldately as they are withdrawn from the reactor.

ftijsWzlattios SigEI mn t operating Procedure

To- chae r the Vi", it is removed from the rocker, opened and

satU" on ead ith the opening upward. The desired amount of asphalt






- 39 -


Figure 3, Polymerization Equipmnt


riire 4, Almaly


r-----
II







Belt ScaL~
Be-It ltet





- 40 -


and solvent is placed in the bomb, the bomb is then closed and the

compression bolts tightened. Particular care must be exercised in

seating the cylinder gasket to avoid scoring or otherwise damaging

it. The compression ring should always be turned with the same

side facing the bolts so that the opposite side will remain smooth.

This may be accomplished by noting which side of this ring has

been previously scarred by the bolts. The bolts should be tightened

evenly by pulling thea down in a "criss-cross" fashion to a torque of

about 20 ft.-lbs. which is ample to seal 6000 p.s.i., as stated by

the mnaufacturer. The bomb assembly should be put together as

shown in Figure h. It is necessary that the retaining bolt be

fastened securely after placing the bomb in the rocker.

After completely assembling the apparatus and all auxiliary

equipment, nitrogen is allowed to flow through for about five minutes

to cqpletely purge air from within. Then the heater, controller,

shaking amchanism, etc. are turned on to bring the apparatus to

the desired temperature and allowed to reach themal equilibrium.

During the run, occasional adjustment of the controller set point

Sby be necessary. After the reactor has reached equilibrium temper-

ature, the n-apamer is added via the sample outlet by forcing it

into the reietor with slight pressure from the nitrogen tank.

Finally, the pressure is adjusted to 100 p.s.l.g. by the reducing

valve at the nitiaen tank. Samples are taken at intervals during

the run ant stewed in a refrigerator to prevent further polymeriza-

tiE..& It e. neeasary to lower the otUlet end of the shaking.

I;vl i ir e ......





41 -







C. Alytical Methods


Determination of oaoer by yd rogatioa

A considerable amount of effort was expected to establish a

suitable means of detersning the eoccentration of the reactants,

i.e., vinyl-moamers in the complex asphalt syj'ttm encountered.

Quantitative selective hydra~gantion has been found to be a reliable

method of analysis. Because of the nature of aaphalts the more

common methods of olefin analysis were discarded for at least o Q or

more reasons.

The following is a list of possible methods of analysis which

might appear to be feasible, but which were discarded by at Ilsat the

reasons indicated:

a) Spectroscaey Aiphealt are esasa.tally opaque to the

region of the spectrum which are~,a plicabe to thbe

arthaUi with the mtertfleeo Nued. (15, 20, 31, 36, 65, .I)

b) halogsnatius Either ijhiggterim iauthiietl 4ith





hlydro-hl .in cur. ifienty is g .


~~~~~~.... iiiiiiii ..................iiiiiiii




- L2 -


c) Aqueous phase addition reactions Apparently all aqueous

systems must be discarded be cause of the occurrence of

the problem of mass transfer in the heterogeneous system

resulting from the precipitation of the asphalts into a

separate phase.(54)

d) Dilatometer techniques The expense of manufacturing

high-pressurentllatmeters capable of operation at a precise

temperature over the wide range of temperature desired is

prohibitive and the ability to obtain precise results

with systems containing only 1-10 percent monomer is

questionable.(20, 79, 10h)

e) Viscosity methods These methods would not be applicable

because no direct conparicon could be iade between the

various asphalts encountered, which is part of the object

of this research.(20, 32)

f) Removal of polymer by precipitation It has not been

possible to discover a solvent which vill precipitate the

polymer from solution without precipitating the asphalts

also. (20)

The above list is included principally to justify use of the

procedure of analysis adopted. This procedure, namely a selective

nicro-hydragenation, is actually quite reliable but very time

consuming and tedious to perform.

Selective hydrogenation of olefins over palladium has been used

by several investigators.(19, 64, 100) However, materials containing




- 43 -


araatic carbaoyl, nitrile and nitro groups nay exhibit interference.

(6, 64) The procedure described here is essentially a modification

of that described by Mitchell.(64) Low blank values have been found

when hydrogenating the various asphalts in the absence of vinyl-mono-

mers, indicating that the procedure followed Ir qte -w eleMtfe Onr

olefins in the systems encounters. Tbbles 5 a-i 6 iiUcate that of aoL

materials studied, only the asphafM; l any be aIs cfl f interfere

in this analysis. In all cases, the asphaltenes have been present

(when removed from the asphalt) in less than 20 percent concentration.

Therefore, approximately 3 x 10-6 g. holes hydrogen per gm. sample

will be used by the asphaltenes in the mxi;a situation.

Refer to Figure 5, a photograph and Figure 6, a scheatic diagram

of the equipment used to obtain details of the equipment construction.

The analytical procedure used is as follows:

a) Weigh accurately a quantity of saamle which will take up

fr m 75 to 100 El. of hydrogen into the appropriate con-

tainer. This is the sample boat shown in figure 6 in the

ose of asphalt samples amr the Victor-Okler type bulb

in the cme where calibration vith pure olefin is desija.

The use of the ma boat allow s. m ewC ioaaIm ama la:,

of the vaiaile caWtitweats of the i ple. ~ai can

ein1*medo by a4ltitid f:l.ip--dt snes with 5 to 6 h.. dr the

sualent xylea- after they Iberl been weighed.

b) mlns1e 50 :1. of 31W:., e a. ipni.ly 0.05 as q.i tbq; il

l daat4i. m

iiiiiiiiiiiiii iiii iii iiiiiiiiii iiiii i iiii




=.....- il- .


TABLE 5, HYDROGENATIOII BLAIK VALUES FOR SEVERAL ASPHALTS



Test Conditions: Hjdrogenation over palladium catalyst at roomc
temperature and pressure for at least eight hours.


nG. holess Equivalence
Hydrogen Per in Weignt
Desigiation Description Gm. Sample % Sty:vne


S117 East Texas Asphalt 7.5 x 10'- 0.078
Base Residuum

511. South Texas Heav. 5.3 x 10- 0.055
Asphalt Base Residuum

5119 Gulf Coast Naphthenic 10 C 0 010
Residuum

S120 East Central Texas 6.6 x 1o- 0.068
Residuum

561-1 Asphaltene free 5119 < 10-" 0.010

861-12 Asphaltene free S120 < 10 0.010

R60-ll Air Blown 5119 < 10" 0.010


TABLE 6, HYDROGENATIOw BLANK VALUES FOR TWO ASPHALTENES



Test Coidetions: Hydrogenation over palladium catalyst at room
temperature and pressure for at least eight hours.


Gm. Moles Equivalence
Hydrogen Per in Weight
Designation Description Ga. Sample ( Styrene


s61-6 Asphaltenes from 5119 1.2 x 10-5 0.125

861-9 Asphaltenes from S120 9.9 x 10" 0.100




- 45 -


Figure 5, Selective catalytic micro-
hydrogenation assewsh.y.


bar, and the sample co i lner into the reactiep anel

as sho&n in Figure 6 aamd. aireile the apparatus.

c) Purge the burette of air and fill it with hydrogn. Turn

on the stirrer andt ter, and adjust the valvew o that

hydrogen will flaw thigh the ractii vessel ta pAlI

it of air. About 30,iMlliIA. hb been tentml ail" to:.

reduce any oxide oa the caaWysat .t ,siiihs thIe eltieon

with hyda4ggan a tblalit a Miier up-taug at, W3aRdMi





- 146 -


......::.:EE:..




- 47 -


occurs. A longer time should be avoided because of sample

evaporation.

d) Vent the ballast tube to the atmosphere, fill the burette

with hydrogen, adjust the valves to connect the burette

with the reaction vessel and obtain an initial burette

reading; checking to make sure that the pressure in the

ballast tube is balanced by the pressure in the burette

via the manometer. Close both vents and empty the sample

containers into the solvent by rotating the ground-glass

joint which supports the sample boat. The Victor-Meyer

bulb, when used, may be broken against the open gaaple

boat by gently shaking the reaction vessel which is

connected to the burette by a flexible coupling. Obtain

the atmospheric pressure and water temperature.

e) Occasional adjustment of the level of the mercury in the

burette is necessary to avoid large pressure differentials

which would otherwise cause leaks to develop. After con-

pletion of the hydrogenation (this is judged by the end

of hydrogen up-take), obtain the final burette reading

after adjusting the pressure to that in the ballast tibe

by means of the leveling bulb. Usually abe"t two to three

hours is required for cqpletiar of the analysis after

complete solution of the saiae is ache-ed. Became of

the shape of the s aple bd.t, the hydiiAz~ptlqp doiStt

tends to gradually ac'ac4late in it. It is thedlfore














Other Methods of Olefin Analysis

Several other test methods were devised for analysis of olefirs,

particularly styrene, and used to check the accuracy of the hydro-

genation procedure. A monWmer volatility test, a test employing

quantitative precipitation of the polymer formed and a bromination

test will be discussed.

The Volatility Test

The purpose of this test is to evaluate the amount of unreacted

mamLer remaining in the samples of nonomer-polymer-asphalt mixtures

resulting from reactions occurring in monomer-asphalt systems. It

is uggarally to be assumed that only the unreacted portion of the

apnmuir is determined. However, this is necessarily only an approxi-

.:jteas because of inherent test limitations. The principle involved

is that of the removal by vacua distillation of the volatile portion

(lii mmer) from a suitably arrange sample at an appropriate tempera-

ue- ad-a pressure.

A kanutant teWmerature oven large enough to contain a large

siZedl li dessicator provided with shelves or a high vacuum oven

i inireqM tfor beating the samples. The ssples themselves are con-

tabat xai the bgftt half of 10 cm. diameter petri dishes covered

wiWthA 'Iith b-] s turam. with the coneavity downward. This allows

any ;~ae Eipte rag flow back into the petri dish rather than

u th s.sib as vs would otherwise be the case.




- 49 -


Using reagent grade chemicals, a solution of the concentration

of 1.00 gram per liter of p-t-butyl.:atcchol dissolved in benzene is

prepared to serve as an inhibitor during the test to prevent further

unwarranted polymerization of the momxmer.

Weigh accurately (t 0.001 gmn.) an approximate 5 gi. sample

into a petri dish and record the total gross weight of sample, petri

dish and watch glass used for the sale. Imandiately add 10 al.

of the solution of p-t-butylcatechol and allow the sample to dissolve.

After solution of the sample, gently tilt the dish several times to

mix the inhibitor. Place the samples in the oven at aseepheric

pressure, adjusting the watch glass so as to caly cover about two-

thirds of the petri dish. This allows more rapid reamval of the

solvent.

When the samples appear nearly dry, remove them fras the oven

and allow them to cool to room teoaerature (overnight is permiesble

since further polymerization will be inhibited). Cover cooletely

and again place the sales in the oven, but this time uaer vacuum

for a period of eight hours before removing san reweighih the

sales. The owvn ast be cold at the start to avoid sample spat-

tering. It my be necessary to vary the taiirature and ji~ieasure

when removing various .aemwr. However, it as..beaen iaut Miti:

*ucceesful remaeal of styane :piger can be ac~ir litl= la

5-6 am. U pressure sad 200 OP .





- 50 -


The weight percent styrene is determined as follows:

% Styrene= 100(Gross ut. loss + Blank. sample wt. gain) (a)
Sample wt.

The Quantitative Precipitation of Polymer (20)

To 100 milliliters of anhydrous methanol in a 250 milliliter

beaker add 25 Pm. of sample. Stir well and place on a steam bath for

five minutes to coagulate the sample. Allow the solution to cool

and filter on a tared Gooch crucible. Dry under an infrared lamp

for five minutes, then allow the polymer to dry to constant weight in

an oven at 70 oC. Cool in a dessicator and weigh.

The weight percent styrene is determined as follows:

% Styrene = % Styrene Charged (Wt. polmer)(0lO)
Wt. Sample

It must be noted that this procedure will work only when asphalt

is not present since methanol will also precipitate a portion of the

asphalt.

The Broadnation Procedure

Refer to the American Society of Testing Materials standard test

D 1158 57T. (11) It must be noted that this method will work only

when the asphalt is present in a small amount since it precipitates

and otherwise interferes in samples which contain an appreciable amount.

A c.anaXrson of the results obtained by these methods with

those obtained by hydrogenation is given in Table 7. The hydrogenation

(a) 'Te blank is determined on an asphalt sample adding only the
p-t-butylcatechol solution. A value of 0.017 gm. appears to be satis-
factory as a result of the average value obtained using several
samples for blank determination. Further attempt at increased
.acuracy is not felt justified in view of the overall accuracy
"of the method .






- 51 -


4 N N



,j r- CN





ia,





4 ..6
o n", a








, 1,- r'












in
r.







j -4
o

















d 4.0
CO 04














r-4
N 0 .2







c o
o i-i



bBrH
I 0 '
I04Cl


0t '-'-
-C) S


i. ) )

II
4343P
T U)If
C).W

fl ^t


0 0 .













N C,
C..


,- -
r- 1 14r










n 4
Ia,








O o











c- r- r-
-iM1













c+

bo g
4-


























*-'--
.4)4
43 4^

434


fl \0 C%










no a VI


C.
















rt 0




I ba o
M tn






"-0
mC'



: r'm








0 -^








T) i-

l?;

;1^



I'laB 0 t


N


0 Nr C
qa)




ca C










CrIH



0 0' 0






0 0P
o *









O tn




SCO














'
0 h I

,I" 4s


w0 o' 0


0 *G





"ICs )
04












N0



0
Iqa




00 %1



gn














... ... ...


o r-4




H -1
C *








0-I CY H
S20



N1 0'







r-I



CU
0-h
30
5.4







ti= .
0----




- 52 -


procedure consistently gives results which are slightly low. This

can be attributed to a slight evaporation of the monomer from

samples during the purging phase of the hydrogenation procedure.

This has also been found to be true for hydrogenation of samples

which have been blended to give a known composition. The error

from this source appears to be less thar 5.0 percent of the total

quantity of monomer present. The results obtained by hydrogenation

and bromination are plotted in Figure 7 in the manner employed for

the use that these data are intended. It can be seen that very

reasonable agreement is obtained, even though the hydrogenation

values are somewhat low.




































































U' 0\
o o N
0-J 0aTA~ro 0ragZoiriP













IV. CAICUIATICOS


A. Method of Calculating Monomer Concentration


Berivetiom of an Equation for Calculating Monomer Concentration From
Hydrognatiocs

wftb obtained,

Initially Finall;


Burette reading
Jacket te merature
System pressure (by reference to
the atmospheric pressure)
Saple weight


Burette reading


From the ideal gas law,

V = nRT

Where: n Ga. males of gas
P Pressure
V Volume
R Ieal gas law constant
T Absolute temperature

itE-rranging gives,

P/T = n=/V

(P/T)baUllt = (nR/V}ballast = a constant
tube tube

(f.i is true for a given determination since
n aw V are coatant.)
afMTnH7,


ballast


systdreeintion
system initial


hPydrogenation
system final


[bam ter reatUng (P /T)
- Jae|t tfbemaature initial = b


- 54 -


h r iiiii ...









Where! b Denotes burette
j Denotes the jacket
i Denotes initial conditions

Note: Under the conditions in which thick test is
performed, use of the ideal gas law is adequately
Justified. (92)

Since the ballast tube provides a means of reference to a

constant (P/T) ratio, minor fluctuations in the temperature of

the water jacket are admissible as long as the entire apparatus is

all at the same temperature. Continuously flowing laboratory tap

water through the apparatus accomplishes this vith no more than a

20F. variation in temperature from beginning to end of the deter-

mination. The amount of gas disappearing may then be calculated

as follows.

h b 10.
Vf = V + f
hp r b 11.
Where: r Denotes reaction flask
b Denotes burette
h Denotes hydrogenation system
f Dc.notes final conditions

From the ideal gas law and substituting from the preceding

equations,

n = Vh PI/RTi = (Vr + Vb )Pi/Ri 12.
i I
n= V P /RT = (Vr Vf 13
nf Yf f r b Pf f 13.

Subtracting equation 13 from equation 12 and substituting the

constant ratio of (P/T) from equation 9, gives,

% = i nf = (V Vb )P/J 14.
i f
Where: o Denotes the change from initial to
final caEnditiao -

Si





- 56 -


However, since the gas is saturated with solvent vapor, a

correction for this error must be applied. The proper correction

factor may be determined as follows,

nH /ln = pH /'p (i.e., partial pressure law for 15.
2 2 ideal gases)
Where: B2 Denotes molecular hydrogen
S Denotes solvent vapor
p Partial pressure

The partial pressure of hydrogen is the total pressure less

the solvent vapor pressure: this gives,


=2 b 5 16.
Rearranging equation 15 and substituting from equation 6l, yields,
p
Pb PS 17.

From a material balance on the gas disappearing,

no= ng + nS 18.
2
Note: The above is approximately true if the small
fluctuation in temperature does not change the
solvent vapor pressure materially.

Substituting equation 17 in equation 18 gives,

n = n.2 x S + 1] 19.


Equating equations 19 and 14, and solving for n.2 gives,

n" = (Vb V) PS)/RTJ 20.
2 1 f
The monmemr concentration may then be calculated as follows,

% Mnoaer = 100 No m/W = 100 m(Vbi pb sb PS)/RTj 21.
2 f
Where: a itameer molecular eight
W Weight of sample hydrogenated











Determination of Solvent Vapor Pressure

In order to use the preceding equation, it is necessary to

estimate the solvent vapor pressure. Several factors which will

affect the exactness with which it Is practical to determine this

value are:

a) The presence of sample as solute in the system. (72)

b) The x lene used is a mixture of the o, p and m isomers

which tend to vary in concentration from batch to bath.

c) There is a sUight variation in temperature over the

extent of the determination.

The last two isomers of xylene noted above predominate in the mixed

system.(80) For this work it has been considered adequate to use the

data presented in Figure 8, which is the vapor pressure of m-sylene.

(57)

Xylene was picked as a solvent because of its ability to

dissolve both the asphalts used and the polymers formed, its low

vapor pressure and ready availability In a grade which has no

observable hydrogenation blank value. (Xylene supplier mentioned

earlier .)

B. Overall Polymerization Rate Constant Calculations


Empirical Determination of the Polymerization Rate Constant

By integration of the equation developed for the polymeriza-

tion process under study, an equation results which aay be rearranged

to give a linear plot when reciprocal concentration is the ordinate

and tim the abscissa.
































: 10 30 50
FigurTe 8, apor of -lene
figure 8, Vapor psmsure of m-xylene


1t

14




59 -





This equation is,

-(M)/dT = K(M)2 22.
Where K has been set equal to: (See page 29)

2 4k D f I
K =(kp k /2k ) ((R ) + ta(2 + k (R *)) -R 23.
p ts ta 2 Ce s a


By separation of the variables and integrating between the limits,

T = 0, T, and M = M, M, the following equation may be obtained,

1/M = KT + 1/M 24.

Where: T Polymerization time, minutes
M Monomer concentration, eight percent
R Stabilized free radical concentration,
No. free rad. per unit weight

By plotting 1/M versus T experimentally determined during a

given polymerization run, a straight line vill be obtained whose

slope is identically equal to the overall rate constant. As a check

upon the experimental data, the intercept of this line with the

ordinate should equal the reciprocal of the miassner concentration

initially charged. This calculatiqp is illustrated in Figure 9,

using the experimental data for Run 60-9.

Correlation of the Tedwerature Effect

Determination of the Activation Energy, H

Previous: to the develop pEt I:: the E yrg theory of slp olut



usd. to .e.v.aluate the effect of theatre up. th.e m i.....
velocity c...e.t. This c&u iis been be Siiiiii;. iiii ta......


to a e.. ...f. a la u.r .f

h.. ..........(.......I.....................1...... ..


a........... ................ ..... ........





- 60-


r-

C.
C

C,
o B

8 CL


8 .




\_ri 0


\ t- -





I IH ,-
\ C







I'-















0 00
C)














10 0 ,


.., ...... .... ,,,i




- 61 -


The Arrhenius equation for correlation of the overall polyeri-

zation rate constant K is given below,

K = A exp (-H/RT) 25.

Where: A Arrhenius frequency factor
H Energy of activation

Taking logarithms of the Arrhenius equation and rearranging

yields,

loglo K = log10 A (0.4343H/R)(1/T) 26.

Therefore, the slope of a plot of log10 K as ordinate versus

(l/T) as abscissa yields a plot whose slope N is,

N = (0.4313H/R) 27.

If R, the ideal gas constant, is taken to equal 1.104 cal.

per gm. mole x OR. and T is in OR., the energy of activation, H, may

determined by,

H = 1.104 N/0.4343 = 2.542 N, cal. per gm. mole 28.

The numerical value of the slope, N, is determined graphically

in a manner analogous to that employed to estimate the value of the

overall polymerisation rate constant as illustrated in Figure 9.

Since the details of this calculation would be repetitious, they are

omitted here.

An Absolute BasiL for ~te Overall Polymertition Iate Coywtmat

Theoretically to be used properly, the K of the. A.rrbhmAi.Mt -

tion must be expressed in :*fM< ,tt of unit which is dlnetly

proportional to tih& number of tom: or sele.lels SAwcting.lpr uait

volume of resotion systt. Fros uiiia0l tuei it, hsqql bqp.i,










this any not be necessary and may even be misleading. Conversion

of the data as obtained experimentally may involve making assumptions

of quantities such as densities, etc., which introduce unnecessary

error into a correlation that might be satisfactory for many purposes

without applying the corrections.

The overall polyaerization rate constant, K ($-1 x min." ), may
be converted to K' in units with an absolute basis (liters per gn.

mole-win.) as follows,

K' = Cf K 29.

Where: cf = 0.1 monomer molecular weight
solution density in gm./cc.

This any be demonstrated in the following mnner,

100 ~. solution gm. monomer cc. solution liter
Am. Ma-omer-ain. om. mole monomer gm. solution cc.

liter per gS. mole-min. 30.

The order of aagnitude of the error introduced in the energy of

activation calculation as a result of neglecting the correction for

density variation with temperature my be estimated. By the method

previously described, I may be determined for a given system in the

f-11 ol iiw aMer,

l 400P lo10K00 31.
00'. 1T200F.
thids ', dmste a corrected value of N and K, the following

is aaa,

W Glogbto. -logWWoF. 32.
(.-I F.-(/)20. 200 .




- 63 -


Sample Calculation for Runs With S 119

For the system, 10 percent styrene and 90 percent S 119, the

solution densities are: 0.911 gin. per cc. at 200 OF. and 0.851 gm.

per cc. at 0 OF. (Refer to Table 8) Therefore (styrene molecular

weight is 104.1),

KiooOF. = 0.1(1lO.l)(K20OOF.)/0.91' 33


,00oF. = 0.1(104 .1)(K4ooOF.)/0.851


Mate rial

Styrene

119 tyrene
10i Styrene


TABLE 8, DE4BITIES OF STYRENE, Sl19 AID
SOLUfIONS OF THESE MATERIALS

Density Density
at 77 F., at 200 F.,
Sgn. er cc. .a. per ce
.902(a) 0.842(a)

0.963(c) 0.922(d)

+ 90o s119 0.914(e)


Density
at 400 F.,
I.F. per cc.

0.744(b)

0.863(d)

0.851(e)


.. .... .... . .. . ... ......
a) Cited in reference (7).
b) Extrapolation of data cited in reference (7).
c) Measured value.
d) Estimated frca the cubical coefficient of expansion cited in
reference (9).
(e) Calculated assuming additivity of densities of the Materala
comprising the solution on a -weight basis.


By reference to Figure 32, pWSe 714, it may be anPd tha",

ilog o K400. glo0 K t = 2.85 3ll



(1/)4 F. (1/)200 = 0.000354 .. .-1


..... .......................-..:: .....
........ .................... .............. ....EEE= ....::::::: .....


II)


I










Substituting these values and the values for density gives,


log10K.OW F. lolO200F. + log14(0.914/0.851)
S- -0.c0035

= (2.35 + 0.0306)/-0.00035h = -8,140 oR. 37.

The value for N determined without applying this correction is

-8,060. This represents an error of,

Percent Error = -081 O) x 100=1% 38.

The energy of activation determined may be expected, therefore, to

be low by about one percent.

Determination of Constants for the Theoretical Rate Equation

The I. B. M. 650 digital computer has been used to calculate

values of K as a function of Rs*. By systematically varying the

parameters it has been possible to obtain calculated curves that

agree approximately with experimentally determined data. This

discussion will be presented later in greater detail.

The program for these calculations has been written for the

I. B. 4. 650 by utilizing the "Flatran" system. This system, which

has been developed at the University of Florida, translates the

proeao'g as written from simplified symbols analogous to those used

in ordinary algebraic calculations, to the more complex language

utilized by the machine carputer.

The equation for the rate constant, K, has been reduced to a

simpler form by substitution of symbols as follows: (See eq. 23, p. 59),

K = A [(R2 + BR + C)2 R] 39


....................










by letting:


A = k ts/2k; B 2= kt k,/s; C = 2kta/s; D = D;

R = *.

The Flatran Program

The Flatran program has been written in accordance with pro-

cedures defined in the Flatran Ianual by Peterson.(73) This program

is designed to calculate values of K in term of R over a range of

R = 10' to 9 x 10" in increments which vary with the magnitude of

R. The Flatran program follows:
0 0001 0 READ,A,B,C,D
0 0002 0 K#A*%SR$R*R&B*$R-*
0 0002 1 DMSCO-RC
0 0000 0 xf#
0 0000 0 1.0000001
0 0000 0 PtN~l ,R,K,A,B,C,D
o 0006 0 *&W
0 0000 0 V2wF
0 0000 0 DOSBEF,G,H
0 0007 0 KrA' As0nQBraW&B*
0 0007 1 DoCa-Ro
0 0008 0 PUCH,R,K,A,B,C,D
0 0000 0 flWOF
0 0000 0 Ir*-o.00o,1,1,1
0 0009 0 STOP
0 0000 0 ED

The m~hlne language program caciled via the flatran pragmw I

included in the Appendix.

C. Calculation of Re~st&ve Free radical C aemtlp

Tia experiantally dete-Otuad data for the varne ouitilt

system has been plotted in the ..~x te g wttOi in t i iMa l ili

i.e., the polyasrization iate a ti-h., K, verla .,b P;i......I.i
.or ethe lti....... s.m Se iii


Sa in tsip -d~ac~iw i-of ren~sa Bflttum~;l ,dlu s;:|iii pi




- 66 -


concentration can be converted to a basis such that the stabilized

free radical concentration can be compared. Experimental data has

been determined to evaluate the free radical concentration in the

various materials on a weight basis. Using these data, which are

given Table 10, page 86, the desired comparison may be made in the

following manner.

Define the ratio of free radicals in the various asphalts on a

weight basis as,

FR ratio of A:B = Free radicals per g. A 4.
Free radicals per gm. B

D. Estimation of the Absolute Free
Radical Concentration


The estimated dlm of the absolute free radical concentration

of the various materials have been given in Table 10, page 86. If

it is assmed that the free radical concentration in an asphalt or

asphaltene solvent system is proprotional to the asphalt concentration

then,

R* = qAU( Species A in the system), 41.

in .g. males free radicals per kgm. of system of A

Where: qA The specie qwtient, a quantity that will
cause the uiats of Ra* to be, ga. moles of
free radicals per kilogram of system of
Species A. Species A may be an asphalt
or aspbalteae.

In ofder to obtain the concentration of R,* in the desired units,

it is neapamary to sate the conversion of units from free radicals per

.-~~t0o s L holes free radical per kh. This may be accomplished by










the uee of equation 42, which follows,
Pree L dioal Cone., in bg. males
.R. per kgm. esa4le2.
Free Radical Cec., in x 1i 1 le
F. R. per p. kpi. u.02Y10 cue

Solving equation 41 for qA gies,

qA Specie A in the in t 93.

The nmerieal value Of qA My be obtained by aing the value

of %R carvepoolndn to 100 percent Of Species A, i. e., for the
coaseam tiea of the asphalt or aspbaltene with no solvent aided.

The specie qmlients neiiwl for systems sauAd ae calculated
below.

1023-
(NO: The nimt Of qA a m WIs 74. jar .m )
% taieas A

(1.1 x 1016 x 1)/6.Oe x 1023
-t* 00 1.83 x 10-7 4.

(4.4 x 1016 x D?3)/6.02 x 1023
q9120 a IM0 i 7-31 x 10-7 45.
(5.7 x 1016 x 103)/6.02 x 1023
l6oo 0 9.17 K 10.7 7 46.

(11 .x 1016 x 103)/6.02 x 1023
qs61.1 a 10 2 18.3 x 10-7 T.













V. RESULT'S


A. Introduction

All of the polymrizations ade in this study have been conducted

is the tinaco autoclave described in the experimental section. This

stuy hba been principally coacermd with the maler in vhich asphalt

a-sati are capbie of interacting in reactions vith vinyl aemomers.

Vinylnreanae ha been the .amaer used in the ajer part of this study.

(tari., imiam rs n eed were o -vinylamphtbalene and vinyl-2-ethylhexanoate.

Swenal typical petmramua residue, representing a vide range of types

2jlily ~countentj Wze the asphalt material used in this study.

".h. :E parties of these saphalts were given in 'able 4, page 33.

h Golf Coast apekthenic residuum, S 119, sad the East Ceotral

"!M ,aditMe, S 120, which represent residue of lor and high

13asi i. am eqest, resoactively, have been studied extesuively.

.. matI fati s bew ales been made in which the asphaltenes removed

iiiww -f hiltse by n-pentame precipitation were used. It will

l .li i nmi"ama tly that the asphaltema fraction of these asphalt

iiqi i# e I wiltfly at the ingredients which are the key to the

.... ...l:.

il3A "in tbhse results is the awaMUr in which the polymri-

g U| iiiii in i af' te *pltia: studied may be correla ted empirically
vhlbU aam wiatl ia _aI r cceatrats s eat reaction tempePature.

ig SiwillHiii this wat is such that a comaidemable mount of

W 4l Ellt all 4,,is:l|it ~a s igatred to ceaduct a single polymerizatirn


- 68 -











run. This run yields a set of data from which may be obtained a

single value, namely K, the overall polymerization rate constant.

With this single value, if the initial concentrations are known,

it is possible to again construct the entire curve representing

the results of this run. Therefore, the quantity of data cited

in this section any appear to be small. The numerical values of

these empirically determined rate constants are tabulated at the

end of this section. The original rau data from the polyerlzation

experiments are given in the appendix.

B. Correlation of Polylerination Rates
With tanomer Comentration


Experimental data are obtained in a tabulated form with the

unreaated maemr concentration (weight percent) measured as a

function of the time elapsed (minutes) from the start of polymer-

ization. It has been fouta that straight lines are obtained if

these data are plotted with reciprocal macear concentratiea (weigh

percent)-l as ordinate, versus the time elapsed (.mnuses) from the

start of polymeri~ati~ o as abscissa. Piguar 10 a d 11 incllpadt in

this section, and Figure 9 of the calculation section and figure 7

of the experimental section have been plot-sd n this awijair Sj

straight line dApendance as shaba in these figu-re is. tyi il of

the data obtained in all of the polyam~Pai ti.As preu-S .


ft~j~f QO f O.... ...... .. .. ....... .1 :::: ... ^" :::: i
This type of data ay be carzdated I-ams- aof-t Sad qar

rate eqttion in teamm of ampimr comoentntten. (Refr ii the .

calculati"a uan.ti.on ) "te ....... l.l.
A *. :





- 70 -


0
0
I 00









0I 0






11 a
o
-I o
r o






0L



S% .











o 0 0 0










v ml
P I iJ d
\ \ s
___ __======___o.=._





- y 1 -


Soo -r


41.


I I D
000







0




x o ( D





( D"
co




C S

I %m






-40








_ -3

^ 43 !



T% 'uouox^J4U90UOQ i^Eea^^s rdfoet




- 72 -


If the units are applied consistently and the data plotted as just

mntiQaed, K will be identically equal to the slope of the line

abtaiind and have the units, (min.)-l(percent mo omer) Here K

has been used as the empirically determined overall polymerization

rate constant.

Check nrms Qn the same system under the same conditions have

agreae within about 10 percent. Data from the runs which have been

Wme in duplicate in this study are presented in Table 9.



TABLE 9, A CiWARISQI OF EXPERMENTALLY DETERMINE PATE
CWdTMITAS TO SaHW REPMIUCIBILITY
.. ... .. .. ... ..... ......... . .. .. ... .

Iagzmijatian Run Coaditims: These runs were charged with the
g~peMt asphalt as indicated below plus a quantity of Styrene
approaching 10% with xylene comprising the difference.

Overall Rate
Teaierature, CCe ant&a
a bB. Aspbalt j Asphalt "F. min. x %L

R61-4 meae -- 300 4.08 x 10-5

R61-5 oea 300 4.12 x 10-5

B61-16 name -- 300 3.96 x 10-5


IjF-19 S 120 90.0 300 10.85 x 10-5

8as2 120 90.0 300 10.09 x 10-5

ai- s 8119 90.0 4oo 1.17 x 10-3

u S 119 90.0 400 1.22 x 10-3
i.... . . ............ ...... . .. . .... .. I I I U

Sk eWalt. of pmaipitfl*e Of the p&e3Q r during the pelyeeriza-

,gAQl^N baris McoaptSAu as a priiDble maruce of erroemsuws mrults.




- 73 -


Petrolatun, a solvent incompatible with the polystyrene, was used to

determine the nag itude of this effect. The rate constant determined

for this run is plotted in Figure 12 for the purpose of comparison

with the data obtained for asphalt systems. It is obvious that the

possible source of error is potentially quite large. The possible

occurrence of a polymer precipitate on the interior of the autoclave

vould be readily observable. This did not ever occur, however, for

polymerization in any of the other solvent systems used.

C. The Arrhenius Correlation

It is apparent from the data given in Figures 10 and 11 that

temperature is a very important variable. This is in accordance with

the effect observed for many reaction system that are essentially

irreversible. As might be expected from the verk of others in the

polymer field, it has been possible to correlate this temerature

dependence by mans of the Arrhenius equation. The sme data shown

in Figures 10 and 11, for the Gulf Coast naphthenic re idua (S U19)

have been used to calculate the overall polymeriation rate constant,

K, and plotted in Figure 12. The second line shown in this figure

is for the air-blown asphalt R60-11.

The slopes of these lines are about -8,060 oR.

The energy of activation, H, is theefore,

H = -1.104 (-8,060)/0.4343 =+20,500 cal. per goi. ple 49.

If a L&. percent peitive. correction is applied, a. ::*i5iid in

the calculatia section, A will be fer thope aptm.:

3 =1.01 (20,500) = 20,700 cal. per ag... Slie. IH0





..4............
















10,000
7,000
5,000

3,000
-

< 1,000 -
. 700
500

S300
.I

100 -
70
S 50
) -

30


-
S 10



I 3


1 -
0.95


1.55


1.35 1.45
Temperature, OR."lx 103


yigae 12, Arrheniue temperature correlation of overall
gigiiuipliuigiti kli rte constrnts.


1.15 1,25
Reciprocal Absolute


- 74 -





- 75 -


Bamford and Barb, in their review of polymerization processes,

cite values of H, the activation energy of the thermal polymeriza-

tion constant of styrene ranging from 19,200 to 23,200 cal. per gm.

mole.(14) These values were determined over the teamerature range

of 0 to 120 C., which is somewhat lover than the temperature range

of this study. It may be noted that the value of B obtained here

is within the range determined by other investigators.

Although the data obtained are insufficient to allow an accurate

calculation of the activation energies (only one or two points

obtained per system), the data of Figure 13 show qualitative agree-

ment with those obtained for the more definitive data presented in

Figure 12.

D. Asgalttene Constituents Exhibit a
Dominant Effect


Data have been obtained to show that cMiements concentrated

in the asphaltene fraction are largely raespasible for the influeneen

that the asphalt studied have had on the poly3er kintics.

Reference to Figure 13 indicates that asphalts having a high

asphaltene content have caused the greatest acce: -satt e of the

polyeirizatioa rate. At a reciprocal ts;dieitare cories.Iafim. .nliti

300 3P., the slte cahd"ite obtained Tor pol.taSi action in, ylewn i la

shown for coeqarisen. This single point represents time results dI

three uns.wme one the sepasaie batches of styre!:im u : ini the rIun



...........
with the aasfplt mys te. tiCe "A" ga 5 ;i hasfliiiibJtiiUI UP.ue;

afl*tlenemi while the "B" (sp has d -i 1.5-2.6 percent j
r.............. ...........




- 76 -


1,000
800
600

loo
00



S200

I

| 100
S80
- 60

10
4o







S8
6



r


SYSTEU
As Indicated 10% Styrene
o Asphalt S 117
* Asphalt S 118
o Asphalt S 119
* Asphalt S 120
A Asphalt R 60-11
A Xylene
(R60-11 is air-blown S119)


1.20


1.25


IN


- A4
Sb ^"


1.30


Reciprocal Absolute Temperature, OR .-x 10

tigur 13, S~ary of the overall polymerisation
rte coataints obtained in the various systems
studied.


A = High Asphaltene Content
B = Low Asphaltene Content








A



B


1 L
1.1


65





- 7 -


It is obvious that the grouping of these data in this manner is

permissible; however, it must also be noted that the sulfur content

(see Table 4, page 33) of the asphalts has a similar relationship.

The asphalt S 119, having a low asphaltene content, and the

asphalt S 120, having a high asphaltene content, were selected for

further investigation of the asphaltene content variable. By

concentration of the asphaltenes in one fraction through n-pentane

precipitation, and removal from the remaining asphalt by filtration,

it was possible to study the two fractions separately. If

asphaltene concentration is an important variable, it should be

possible to observe its effect by dilution of the asphaltene with

a suitable inert solvent, or solvent having known effects. Xylene

was chosen because it is mutually compatible with styrene,

asphaltenes and polymer, and is known to have no acceleration

influence of its own. The results of these experiments are shown

in Figure 14. It can be seen that at low asphaltene coaeentratima,

acceleration of the polymeristlen is paemosmoed. As the caames-

tration is increased, this acceleratieni gradually disappears. Also,

it can be seen that differeacee in the character of the asphalteee

themmnlves have a netionable effect on the rate, since the

asplaltenes fra S 120 gave a substantially greater accelontims

than did the aephal tes from 8 119.

epeating these apewiments with the basw aaphalta S 119 an

S 120 yielAld aults ealupmse to they obhflmed for the agiaalatenes.

TMMe resla 0s. abmn in piguwe 15. An iWaoflant dsiffueamse tald






- 78 -


I I






to n
ete U3 00



L I..








V CII I

SII V)

n 11 r
oCV l
LQ r-rl


_-1 -
x
_ _______ I _


x-


I n n*--

4 H r


r


LIC -I


CD
H




'0


0






0
r

o









S o
SU
H a

o "i nl









t oL


5- ^


-4

--3







.4-


c-. XT- 'u'AR 50OT x 1 ietsuoD e0B uoyTIZ-laLod













x x e-Q----- 0
-I----- I- i I 0









00
0





C 0.





r-- ,-< al

00 -V
-. I I I o






o o
c( X o





















O v co
'


d rp






.o o0
r p. &. ci. c i r *' '4-




CI I

0 '0S ('!


f E!










- --------- t ------ 38 !





- 80 -


be noted for these plots since the concentration variable is extended

considerably in Figure 15. These data indicate the diluting effect

of the inert asphalt fractions. Polyerizations at the concentration

of asphalt yielding the maislm rates, were mde, using the asphaltene

free residues (ceataining less than 0.3 wt. percent). The results

ef these pelmarizabtieo ruas are shown in Figure 15. The acceler-

ation of polySerization noted for the original asphalts, at the

coneEtrati n of asphalt yielding the maxiimu rates, was greatly

reduced. This streagly demnstratat that the asphaltene fraction and

constituents contalned therein are a key factor of this phenomenon.

Mmiftse should be made of phenomena which are annifest for the

asphalt systems, not observed for studies of the asphaltene fractions.

As relatively high asphalt comcentratinas are reached, the polyMeriza-

1tiL is again accelerated. Clarification of the cause of this vill

be covered in the discussion of results.

Earlier in this section it was noted that asphalts with high

aigalt~bl e content had the greatest acceleration influence. Among

this gre a ws the air-blown asphalt R60-11, prepared from S 119.

Ina 0F1ie 16, the eencemtBtion variable for S 119 and R60-11 is

Awil d. S M leans ti a obtained for the air-blown asphalt is

'- partbslarly Odmif sbhed by increasing asphalt concentration, as

it the den for the midim S 119.

Altheigh it ha not been explicitly stated, styrene has been

ap oLy inmWpr ftr which %gilmlt have been cited up to this point.

imAiwbr to ua alisze this sti y, other mmemrs were included.







- 81 -


8 a X X *t o

|J x_'"uTI *Tpr x 2 I7uiUtUo 3 esa uOalis FMCitEo


co
1-a


-4


0




0
rt








o
Eg










I-













s *r


...................::::::::::::::::::::: ::::::::::::::::::::::




- 82 -


Alpha-vinylnaphthalene and vinyl-2-ethylheanoate were polymerized

in xylene and in sylene containing asphaltenes obtained from the

asphalt S 120. Vinyl-2-ethylhexanoate which had no measurable thermal

polymerization of its own was not caused to polyerize by the addition

of the asphaltene. The presence of asphaltawes did affect the

polymerization rate of o(-vinylnaphthelene.

Since no polyaerization occurred for vinyl-2-ethylhexanoate, the

data obtained are not included. A control test containing one percent

benzoyl peroxide in this monomer caused gelling to occur at 200 OF.

in 2.5 hours.

The data detained for o -vinylruphthalene is plotted in Figure 17.

Because very few points were Cbtaiaed for this system, the curve drava

B iee e w e dehed. Data w r limited because of the high cost of

this ce gout. 2The is qualitative agreement of these data with those

baMin for the styrene system. The magnitude of the observed

effect is not large, being of the order of the anticipated exprl-

Smental error for these poly% risation experlimls.

I5. aInaee of a Pure Stable Fuse Radioal


Sgb~lifed free incals were supeoted of being the comtituent

przaet in the asplalteae fractm .vhich is rsponible for the

li;Ej iewsd-. l2afdments usi ,l-d 1,1-phbel-2-picrylhydrazyl

yiM~idet: the esls ple*sed in figue 18. Althlgh the data are

fhi ,st aebrieli a, there is at least an izdica tla of an acceleration

defeat fou.tstm- by a., giM Il aieemm of this effect as the fae

..l4mala ca .atp is incnrawed. It is believed that the


















0









































Cl)
---- -------



400
WA* 11.41 x

C4
T





- B4 -


e




-l I
I -- -


S1-1 r- .

























-9-
r a


















~\-^-~^

-r


K L


0 N -t C. -


0 % -1J c

u..TX 501 xL~O' X Luiouoo e 4uH uoT.,4vz-pxIriS"[o


CO







0 0



C. C








-H 0
c o







0 0
.c c






C O


a r--




















C
CI. 0 -

8 II


> 00
C t 0i.











r-4.


a





- 85 -


acceleration noted here is definite, based on the reproducibility

of the experiments conducted in pure xylene. The spread in the

values obtained at the maximum is probably caused by the delicate

balance of factors responsible for the occurrence of this maximum

acceleration.

F. Spectroscopic Evidence of be Existence
of Stable Free nt-


The four asphalts used in this study, and the two asphaltenes

prepared from these asphalts were submitted for analysis by ESR,

on a contract basis, to the:

Ridgefield Instrument Group
Schlumberger Corporation
P. 0. Box 337
Ridgefield, Connecticut

The determinations were made on a relative basis by comparison at

the sane instrument gain. Examination was umade at a field-strength

of 3,380 gauss, with a micro-wave frequency of 9.47 kileamgacycles.

The spectroscopic splitting factor, "g", was determined to be

2.0021 for these materials. This is quite close to the theoretical

value which can be calculated for the free-electron, i.e.,

2.0023.(52)





- 86 -


TABLE 19, IE RADICAL COCENTRATIO CO THE ASRHALTS
AND ASPrA LMEES USED IN THIS STUDY


(a)
Calculated
Sample Relative Signal
(Instrument Value/gm.)


(b)
Concentration
Free Radicals/gm.


Asphalts


s 117

s l18

S 119

S 120


16
5.1 x 101

0.47x 1010

1.1 x 101


Asphaltenes


5 61-6

S 61-9


5.7 x 1016

11 x 1016


1281


(a) These values are estimated to be accurate to within about
10 percent of the value determined. They are the average
"f determinations made In duplicate.

(b) Deeradined by comparison with a 0.002 M aqueous solution
of ME tal-.

(c) easureennts were made by Schlutberger Corporation using a
Strand Labs modell So. 600 spoctrcmeter at 9.47 kae. and
3380 gane. Sbaplea were prepared by means of scooping
1.5 m. dieter pyrex capillary tubes.


"NEW











TABLE 11, GRAPHICALT.Y DETEPKTNED C'VERALL PCLYMERIZATITC RATE CONSTANT FGR
.LIRUS ITH THE GULF COAST NAPHTENIC R ESIDUUM (S119), STYREVE AND .TLENE


Polymerization Run Conditions: Theae runs were charged with the percent
S119 as indicated below, plus a quantity cf ?tyrene approaching I04,
with 'Xylene comFrisrng the difference.


Overall Rate
Temperature, Constant
Pun No.. 119 (Ln.-1 x -

R61- 4 0.0 300 4.08 x 10-5
F61- 5 0.0 300 4.12 x 10-5
R61-16 0.0 300 3.96 x 10-5
P61-48 2.91 300 9.32 x 10-5
R61- 3 4.97 300 9.92 x 10-5
R61- 6 4.99 300 10.57 x 10-5
R61- 7 14.9 300 6.54 x 10-5
R61- 2 29.8 300 500 .x 10-5
R61- 8 36.9 300 4.38 x 10-5
R61- 1 6c.6 300 4.75 x 10-5
F6C- 5 90.0 300 5.87 x 10-5
R60-1C 89.2 200 1.07 x 10-6
R60- 9 89.8 250 7.22 x 10-6
P60- 4 90.0 400 1.17 x 10-3
R60- 3 90.0 400 1.22 x 10-3

The foll.-wing run was made with 5119 after removal of asphaltenes by
preciFitation with n-pentane. This material designated .61-1.


Cverall Rate,
TemTerature, Constant
Run No. % 61-1 OF. (min.-1 x %1)


300 5.79 x 10-5


6l1- 9 4.83











TABLE 12, GRAPHICALLY rETEPRMIJET CVoRALL PKLYTEPRIZATTCI RATE CCrJSTANT FCR
RUTS ~rWTH THE EA3T CE-TRAL TEXAS RESTPUUM (3120), STYRELE A!D T EE


Polymerizaticn Run Conditions: These runs were charged with the percent
S120 as indicated bel-w, plus a quantity cf ?tyrene approaching 10C',
with Xylere comprising the difference.


Temperature,
Run lo. 9 "120 OF.


R61- U
R61- 5
R61-16
R61-24
R61-23
R61-22
R6f1-18
R61-17
R61-31
R61-32
R61-33
R61-35
R60-19
R60-22
R60-21


0.0
0.0
0.0
0.266
0.839
1.63
3.21
6.39
29.9
60.0
75.3
84.2
90.0
90.0
90.0


-verall Rate
Constant
(min.-l x t-1)


4.08
4.12
3.96
9.14
15.4
13.05
10.78
8.92
5.32
5.56
5.83
8.33
10.85
10.09
1.65


10-5
10-5
10-5
10-5
10-5
10-5
10-5
10-5
10-5
10-5
10-5
10-5
10-5
10-5
10-3


The following run was made with 3120 after removal of asphaltenes by pre-
ei station with n-pentane. This material designated !61-12.


Temperature,
Run No. % S61-12 OF.


Overall Rate,
Constant
(min.-1 x -1)


0.837 300 4.96 x 10-5





-89-


T.AbBTE 13, GRAPHICS'Y DETERi'N!ET," :'TAl[ PR'YIERZATI:; RATE CONSTANT
F.R RUT.S .*ITH 500'F. AIR 5BL:T 5119 (R60-11), nTYFP.E 4b ViTEliE



Polymerizaticr, r'un Conditions: 'hese runs were charge with the percent
60-11 as indicate below, plus a quantity of Ct:rene approaching 10f,
with yylene comprising the difference.


Temperature,
Wur. lIurr.er RPC-r! F.


61l-4

R61-5

R61-16
E61-!65



rAl-46

R61-1^

E61-49



FR60-13

R60-12

R60-14


0.0


O.O
C. C.

573





1?.C

54.8

89.9

29.9

90.1


Coverall Fate
rcnstant
(min.-I x 1-1)


4.08

4.12

3.96

7.06

8.95

9.93

e.35

2.73

8.52

2.13

6.55




- 90 -


TAPE 14, GR4FHICAUY D.TFFURMIT:ED C'TERATL P.:ClTiERIATIC? RArTE Ci-:JTAf:T
FCR RUI'S WITH 'JP.RI.:US PLTR';EU MATERIALS




Pclymerisation FRn Conditions: These runs were charged with the material
as indicated below, plus a quantity nf Ftyrene aprr-aching 10..


Run Number Material


R60-15(a) z60-i
(S60-1 is petrolaturm)


R60-20




R60-18


Temperature,
-F.


200'


ll7 300 :
('l17 is the East Texas
Asphalt Base Resitwum)


S118 300
(S118 is the South Texas
Heavy Asphalt Base
Residuum)


overalll Pate
Cc rtart
(min.-l x f-1-



1.L-9 x 10-5



eP.6 x 10-5


5.8c x 10-5


(&)A dhinit& precipitation of polymer occurred on the interior of
the "u'toclave during this run.




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