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A study on processing of cellulose and its interaction with supercritical carbon dioxide and co-solvent.

Permanent Link: http://ufdc.ufl.edu/UFE0042836/00001

Material Information

Title: A study on processing of cellulose and its interaction with supercritical carbon dioxide and co-solvent.
Physical Description: 1 online resource (126 p.)
Language: english
Creator: SELARKA,ANIKET
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2011

Subjects

Subjects / Keywords: BIOBASED -- BLENDS -- CARBON -- CELLULOSE -- DIFFRACTION -- DIOXIDE -- FLUIDS -- HYDROGEN -- INFRARED -- SPECTROSCOPY -- STARCH -- SUPERCRITICAL -- XRAY
Materials Science and Engineering -- Dissertations, Academic -- UF
Genre: Materials Science and Engineering thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: An ecological alternative to reduce plastic waste is to use biodegradable polymer blends and composites using natural polymers. Cellulose is the most abundant natural polymer on earth. However, one of the significant factors that restrict its use at higher levels in blends and composites is high crystallinity. This characteristic comes from extensive inter-chain and intra-chain hydrogen bonds between hydroxyl groups. Supercritical carbon dioxide (CO2) has been known for efficient plasticizing effect in polymer processing. In this work, the effect of supercritical CO2 on mechanical properties of a twin-screw extruded Low Density Polyethylene (LDPE)-cellulose blend (70-30) was studied. The supercritical CO2 assisted LDPE-Cellulose blend showed 300% increase in tensile strain at break compared to non-CO2 assisted LDPE-Cellulose blend. Moreover, the strain at break of supercritical CO2 assisted LDPE-Cellulose blend matched with that of LDPE-Starch blend. An attempt to change the inherent crystallinity of cellulose was performed by exposing it to two systems viz. Dimethyl Sulfoxide (DMSO)-supercritical CO2 and DMSO-Urea-supercritical CO2. The change in relative crystallinity was studied by Wide Angle X-Ray Diffraction (WAXD). The samples were characterized by using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFT) in order to study the changes in molecular structure preferably hydrogen bonding due to processing under such systems. The samples were also characterized by 13C Nuclear Magnetic Resonance (NMR) technique to acknowledge understanding developed from the DRIFT measurements. The cellulose samples processed in DMSO-supercritical CO2 system showed a reducing trend of the relative crystallinity with increasing pressure. A maximum 40% reduction was achieved when cellulose was processed with DMSO-supercritical CO2 at 4500 psi. The reduction in the relative crystallinity occurred due to weakening of inter-chain hydrogen bonds in cellulose. The cellulose samples were processed in DMSO-urea-supercritical system at 2500 psi and 4500 psi. The amount of urea added in cellulose was in the range of 0.25 to 1.00 g per 1.5 g of cellulose. Over 50% reduction in relative crystallinity was found in most of the samples. This reduction in crystallinity was due to the presence of a DMSO-urea complex, which caused weakening of intermolecular hydrogen bond and an intramolecular hydrogen bond. The supercritical CO2 assisted extrusion processed LDPE-Cellulose blend (70-30) was proved a suitable alternative of LDPE-Starch blend of the same composition. Batch Processing of microcrystalline cellulose in DMSO-supercritical CO2 and DMSO-Urea-supercritical CO2 showed significant reduction in relative crystallinity compared to that of unmodified cellulose. The reduction in crystallinity occurred due to disruption of the molecular structure that was caused by weakening of hydrogen bonds.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by ANIKET SELARKA.
Thesis: Thesis (Ph.D.)--University of Florida, 2011.
Local: Adviser: Baney, Ronald H.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2012-04-30

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2011
System ID: UFE0042836:00001

Permanent Link: http://ufdc.ufl.edu/UFE0042836/00001

Material Information

Title: A study on processing of cellulose and its interaction with supercritical carbon dioxide and co-solvent.
Physical Description: 1 online resource (126 p.)
Language: english
Creator: SELARKA,ANIKET
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2011

Subjects

Subjects / Keywords: BIOBASED -- BLENDS -- CARBON -- CELLULOSE -- DIFFRACTION -- DIOXIDE -- FLUIDS -- HYDROGEN -- INFRARED -- SPECTROSCOPY -- STARCH -- SUPERCRITICAL -- XRAY
Materials Science and Engineering -- Dissertations, Academic -- UF
Genre: Materials Science and Engineering thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: An ecological alternative to reduce plastic waste is to use biodegradable polymer blends and composites using natural polymers. Cellulose is the most abundant natural polymer on earth. However, one of the significant factors that restrict its use at higher levels in blends and composites is high crystallinity. This characteristic comes from extensive inter-chain and intra-chain hydrogen bonds between hydroxyl groups. Supercritical carbon dioxide (CO2) has been known for efficient plasticizing effect in polymer processing. In this work, the effect of supercritical CO2 on mechanical properties of a twin-screw extruded Low Density Polyethylene (LDPE)-cellulose blend (70-30) was studied. The supercritical CO2 assisted LDPE-Cellulose blend showed 300% increase in tensile strain at break compared to non-CO2 assisted LDPE-Cellulose blend. Moreover, the strain at break of supercritical CO2 assisted LDPE-Cellulose blend matched with that of LDPE-Starch blend. An attempt to change the inherent crystallinity of cellulose was performed by exposing it to two systems viz. Dimethyl Sulfoxide (DMSO)-supercritical CO2 and DMSO-Urea-supercritical CO2. The change in relative crystallinity was studied by Wide Angle X-Ray Diffraction (WAXD). The samples were characterized by using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFT) in order to study the changes in molecular structure preferably hydrogen bonding due to processing under such systems. The samples were also characterized by 13C Nuclear Magnetic Resonance (NMR) technique to acknowledge understanding developed from the DRIFT measurements. The cellulose samples processed in DMSO-supercritical CO2 system showed a reducing trend of the relative crystallinity with increasing pressure. A maximum 40% reduction was achieved when cellulose was processed with DMSO-supercritical CO2 at 4500 psi. The reduction in the relative crystallinity occurred due to weakening of inter-chain hydrogen bonds in cellulose. The cellulose samples were processed in DMSO-urea-supercritical system at 2500 psi and 4500 psi. The amount of urea added in cellulose was in the range of 0.25 to 1.00 g per 1.5 g of cellulose. Over 50% reduction in relative crystallinity was found in most of the samples. This reduction in crystallinity was due to the presence of a DMSO-urea complex, which caused weakening of intermolecular hydrogen bond and an intramolecular hydrogen bond. The supercritical CO2 assisted extrusion processed LDPE-Cellulose blend (70-30) was proved a suitable alternative of LDPE-Starch blend of the same composition. Batch Processing of microcrystalline cellulose in DMSO-supercritical CO2 and DMSO-Urea-supercritical CO2 showed significant reduction in relative crystallinity compared to that of unmodified cellulose. The reduction in crystallinity occurred due to disruption of the molecular structure that was caused by weakening of hydrogen bonds.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by ANIKET SELARKA.
Thesis: Thesis (Ph.D.)--University of Florida, 2011.
Local: Adviser: Baney, Ronald H.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2012-04-30

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2011
System ID: UFE0042836:00001


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Full Text

PAGE 15

1.1 Motivation

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1.2 Engineering and Scientific Approach

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1.3 Organization of the Dissertation

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et al.

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et al. et al.

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2.1 Bio Based Materials et al.

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2.1.1 Cellulose and Starch St ructure and Properties

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et al.

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2.1.2 Characterization of Cellulose et al. et al. et al.

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et al.

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et al. et al. et al. et al. et al. et al.

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et al. et al. et al. et al. et al. 2.1.3 Cellulose (and Derivatives) Based Polymer Blends

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et al. et al.

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et al.

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et al. et al.

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et al. et al. et al.

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et al. et al. et al.

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2.2 Supercritical Fluids 2.2.1 Properties of Supercrit ical Fluids

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et al.

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2.2.2 Supercritical CO2 and CoSolvents

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et al.

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et al. 2.3 Polymer Processing with Supercritical CO2 ( and CoSolvents ) et al. et al. et al.

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et al.

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et al. et al. et al. et al. et al.

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et al. et al. et al. et al. et al. et al.

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et al. et al. et al.

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et al. et al.

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et al. et al.

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et al.

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et al. et al.

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et al. et al.

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et al. et al.

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et al.

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3.1 Polymer Processing Twin screw Extrusion and Injection Molding

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3.2 Tests and Analysis

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4.1 Materials

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4.2 Experiment Setup 4.3 Experiment Procedure

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5.1 Wide Angle XRay Diffraction Measurement

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5.2 Effect of DMSO and Supercritical CO2 on Crystallinity of Cellulose

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5.3 Effect of Urea on Crystallinity of Cellulose

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6.1 DRIFT Measurement

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6.2 Effect of DMSO Supercritical CO2 on Cellulose

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6 .3 Effect of DMSO Urea with Supercritical CO2 on Cellulose

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6.3.1 Effect of Urea Concentration at Processing Pressure of 2500 Psi

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6.3.2 Effect of Urea Concentration at Processing Pressure of 4500 Psi

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et al. et al. et al. et al. et al.

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7.1 Nuclear Magnetic Resonance Measurements

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7.2 Results and Discussion

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8.1 Conclusion

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8.2 Future Work

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Cellulose 2009, 16