Nanocomposites and Blends with Poly(Butylene Adipate-Co-Terephthalate)

216 Pages·2011·10.96 MB·English

by  Vidhate, Shailesh

BIODEGRADABLE POLY(HYDROXY BUTYRATE-CO-VALERATE)

NANOCOMPOSITES AND BLENDS WITH POLY

(BUTYLENE ADIPATE CO-TEREPHTHALATE)

FOR SENSOR APPLICATIONS

Shailesh Vidhate, B.E., M.S.

Dissertation Prepare d for the Degree of

DOCTOR OF P HILOSOPHY

UNIVERSITY OF NORTH TEXAS

December 2011

APPROVED:

Nandika D’Souza, Major Advisor
Vijay Vaidyanathan, Committee Member
Witold Brostow, Committee Member
Nigel Shepherd, Committee Member
Mohamed El Bouanani, Committee
Member
Narendra Dahotre, Chair of the
Department of Materials Science
and Engineering
Costas Tsatsoulis, Dean of the College
of Engineering
James D. Meernik, Acting Dean of the
Toulouse Graduate School
Vidhate, Shailesh. Biodegradable Poly(Hydroxy Butyrate-Co-Valerate)
Nanocomposites and Blends with Poly(Butylene Adipate-Co-Terephthalate) for Sensor
Applications. Doctor of Philosophy (Materials Science and Engineering), December
2011, 197 pp., 69 figures, 19 tables, chapter references.
The utilization of biodegradable polymers is critical for developing “cradle to
cradle” mindset with ecological, social and economic consequences. Poly(hydroxy
butyrate-co-valerate) (PHBV) shows significant potential for many applications with a
polypropylene equivalent mechanical performance. However, it has limitations including
high crystallinity, brittleness, small processing window, etc. which need to be overcome
before converting them into useful products. Further the development of biodegradable
strain sensing polymer sensors for structural health monitoring has been a growing
need. In this dissertation we utilize carbon nanotubes as a self sensing dispersed
nanofiller. The impact of its addition on PHBV and a blend of PHBV with poly(butylene
adipate-co-terephthalate) (PBAT) polymer was examined. Nanocomposites and blends
of PHBV, PBAT, and MWCNTs were prepared by melt-blending. The effect of MWCNTs
on PHBV crystallinity, crystalline phase, quasi-static and dynamic mechanical property
was studied concurrently with piezoresistive response. In PHBV/PBAT blends a rare
phenomenon of melting point elevation by the addition of low melting point PBAT was
observed. The blends of these two semicrystalline aliphatic and aromatic polyesters
were investigated by using differential scanning calorimetry, small angle X-ray
scattering, dynamic mechanical analysis, surface energy measurement by contact angle
method, polarized optical and scanning electron microscopy, and rheology. The study
revealed a transition of immiscible blend compositions to miscible blend compositions
across the 0-100 composition range. PHBV10, 20, and 30 were determined to be
miscible blends based on a single T and rheological properties. The inter-relation
g
between stress, strain, morphological structure and piezoresistive response of MWCNT
filled PHBV and PHBV/PBAT blend system was thoroughly investigated. The outcomes
of piezoreistivity study indicated MWCNT filled PHBV and PHBV/PBAT blend system as
a viable technology for structural health monitoring. Finally, the compostability of pure
polymer, blend system, and MWCNT filled system was studied indicating that PBAT and
CNT decreased the biodegradability of PHBV with CNT being a better contributor than
PBAT.
Copyright 2011
by
Shailesh Vidhate
ii
ACKNOWLEDGEMENTS

I would like to express my heartfelt gratitude to my major advisor Prof. Nandika
D’Souza for accepting me to conduct research in her lab and for her continual guidance,
support and encouragement throughout my doctoral program without which this
dissertation would not have been possible.
I would like to thank Prof. Vijay Vaidyanathan for his guidance as a committee
member. Advice from my committee members Prof. Whitold Brostow, Prof. Nigel
Shepherd, and Prof. Mohamed El Bouanani is highly appreciated.
I am grateful to all the help rendered by Sandeep Manandhar and Mangesh Nar
whenever I needed. A special thanks to Koffi Dagnon, Ali Shaito, and Mark Pickens for
training me on PMRL lab equipments and their frequent guidance. Thanks to Dr. David
Diercks, Dr. Nancy Bunce, and Dr. David Garrett of UNT-CART for giving me
equipments training and generous assistance in the use of CART equipments. I would
like to thank the members of MTSE departmental staff: Joan Jolly, Wendy Agnes, April
Porter, and John Sawyer.
I am grateful to all the help and support rendered by Tea Datashvili, Mohammad
Maneshian, Sunny Ogbomo, Emmanuel Ogunsona, Dong Le, Dinesh Ramesh and all
the students and staffs of Materials Science and Engineering for the good times
together.
I am forever indebted to my parents Pandit Vidhate and Padma Vidhate; and my
fiancée Gauri Khandekar for their care and support in every aspect of my life.
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TABLE OF CONTENTS

ACKNOWLEDGEMENTS ............................................................................................... iii
LIST OF TABLES ............................................................................................................ x
LIST OF FIGURES .......................................................................................................... xi
CHAPTER 1 DISSERTATION SCOPE AND BACKGROUND ........................................ 1
1.1 Introduction ..................................................................................................... 1
1.2 Objective......................................................................................................... 2
1.3 References ..................................................................................................... 4
CHAPTER 2 POLYMER/CARBON NANOPARTICLE NANOCOMPOSITES ................. 6
2.1 Introduction ..................................................................................................... 6
2.2 Nanocomposites ........................................................................................... 11
2.2.1 How Nanocomposites Work? .......................................................... 12
2.2.2 How to Produce Nanocomposites? ................................................. 13
2.3 Polymer Carbon Nanoparticle Composites ................................................... 15
2.4 Carbon in Various Forms .............................................................................. 15
2.4.1 Carbon Nanofibers .......................................................................... 16
2.4.2 Carbon Nanotubes .......................................................................... 17
2.5 Dispersion of Nanotubes in Polymer Matrix .................................................. 19
2.6 Percolation Theory ....................................................................................... 22
2.7 Piezoresitivity in CNT Filled Nanocomposites .............................................. 24
2.8 References ................................................................................................... 24
CHAPTER 3 POLY(3-HYDROXYBUTYRATE-CO-3-h DROXYVALERATE)/
MULTIWALL CARBON NANOTUBES NANOCOMPOSITES ....................................... 29
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3.1 Introduction ................................................................................................... 29
3.2 Experimental ................................................................................................. 31
3.2.1 Materials ......................................................................................... 31
3.2.2 Nanocomposites Preparation .......................................................... 31
3.2.3 Measurements and Characterization .............................................. 32
3.3 Results and Discussions............................................................................... 35
3.3.1 Mechanical Properties .................................................................... 35
3.3.2 Differential Scanning Calorimetry (DSC) ......................................... 39
3.3.3 X-Ray Analysis................................................................................ 42
3.3.4 Electrical Resistivity ........................................................................ 44
3.3.5 Transmission Electron Microscopy (TEM) ...................................... 45
3.4 Conclusion .................................................................................................... 47
3.5 References ................................................................................................... 48
CHAPTER 4 BIODEGRADABLE PIEZORESISTIVE MULTIWALL CARBON
NANOTUBE/POLY(3-HYDROXYBUTYRATE-CO-3-HYDROXYVALERATE)
COMPOSITES .............................................................................................................. 50
4.1 Introduction ................................................................................................... 50
4.2 Experimental ................................................................................................. 53
4.2.1 Materials ......................................................................................... 53
4.2.2 Sample Preparation ........................................................................ 54
4.2.3 Measurements ................................................................................ 54
4.3 Results and Discussion ................................................................................ 57
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4.3.1 Compressive Stress and Resistance Response under Quasi-Static
Loading .................................................................................................... 57
4.3.2 Composite Resistivity ...................................................................... 59
4.3.3 Compressive Creep and Resistance under Transient Creep .......... 59
4.3.4 Cyclic Loading and Electric Resistance Response of Composites . 62
4.4 Conclusion .................................................................................................... 63
4.5 References ................................................................................................... 63
CHAPTER 5 CRYSTALLINE/CRYSTALLINE POLYMER BLENDS ............................. 66
5.1 Introduction ................................................................................................... 66
5.2 Polymer Crystallization ................................................................................. 70
5.3 Polymer Crystal Structure and Characterization ........................................... 71
5.4 Crystallization in Polymer Blends ................................................................. 74
5.4.1 Complete Immiscible Blends ........................................................... 74
5.4.2 Crystallization in Blends with Miscibility Gap .................................. 75
5.4.3 Crystallization in Miscible Blends .................................................... 76
5.5 Crystalline/Crystalline Polymer Blends ......................................................... 76
5.6 References ................................................................................................... 87
CHAPTER 6 MISCIBILITY, CRYSTALLIZATION, AND MELTING BEHAVIOR OF
PHBV/PBAT CRYSTALLINE BLENDS ......................................................................... 91
6.1 Introduction ................................................................................................... 91
6.2 Experimental ................................................................................................. 94
6.2.1 Materials ......................................................................................... 94
6.2.2 Blend Preparation ........................................................................... 94
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6.2.3 Film Preparation in Carver Compression Press .............................. 94
6.2.4 Characterization .............................................................................. 95
6.3 Results........................................................................................................ 102
6.3.1 Differential Scanning Calorimetry.................................................. 102
6.3.2 Crystalline Structure of PHBV/PBAT Blends Analyzed by WAXD.......
............................................................................................................... 107
6.3.3 SAXS ............................................................................................ 108
6.3.4 Contact Angle and Surface Energy ............................................... 115
6.3.5 ESEM ............................................................................................ 117
6.3.6 Polarized Optical Microscopy ........................................................ 118
6.4 Discussion .................................................................................................. 121
6.4.1 Melting Point Elevation in Polymer Blends .................................... 121
6.4.2 Miscibility Analysis ........................................................................ 124
6.5 Conclusion .................................................................................................. 137
6.6 References ................................................................................................. 138
CHAPTER 7 MECHANICAL AND RHEOLOGICAL BEHAVIOR OF PHBV/PBAT
BLENDS ...................................................................................................................... 140
7.1 Introduction ................................................................................................. 140
7.2 Experimental ............................................................................................... 143
7.2.1 Materials and Blends Preparation ................................................. 143
7.2.2 Dynamic Mechanical Analysis (DMA) ........................................... 143
7.2.3 Tensile Testing.............................................................................. 144
7.2.4 Rheological Measurement ............................................................ 144
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7.3 Results and Discussion .............................................................................. 145
7.3.1 Dynamic Mechanical Analysis ...................................................... 145
7.3.2 Tensile Testing.............................................................................. 151
7.3.3 Rheology ....................................................................................... 153
7.4 Conclusion .................................................................................................. 159
7.5 References ................................................................................................. 160
CHAPTER 8 PIEZORESISTIVE PROPERTIES OF CONDUCTIVE PHBV/PBAT
BLEND WITH MULTIWALL CARBON NANOTUBES ................................................. 162
8.1 Introduction ................................................................................................. 162
8.2 Experimental ............................................................................................... 164
8.2.1 Materials ....................................................................................... 164
8.2.2 Composite Sample Preparation .................................................... 164
8.2.3 Resistance Measurements ........................................................... 165
8.2.4 Scanning Electron Microscopy (SEM) ........................................... 165
8.3 Results and Discussion .............................................................................. 166
8.3.1 Mechanical and Electrical Response under Compression ............ 166
8.3.2 Resistance Response for Creep and Relaxation .......................... 168
8.3.3 SEM .............................................................................................. 170
8.4 Conclusion .................................................................................................. 172
8.5 References ................................................................................................. 172
CHAPTER 9 EFFECT OF POLY (BUTYLENE ADIPATE-CO-TEREPHTHALATE),
CARBON NANOTUBES ADDITION ON AEROBIC BIODEGRADABILITY BEHAVIOR
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