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Self-Healable, Reprocessable, and 3D Printable Plant Oil-Based Elastomers and Facile Fabrication of Graphene Oxide Reinforced Copolymer Nanocomposites
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- Author / Creator
- Rahman, Saadman Sakib
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Prolonging service-life and durability of polymer-based products can help to reduce severe landfill/marine pollution caused by polymeric materials (i.e., elastomers and thermosets). Self-healing polymers are a class of polymers that are capable of healing cracks or mechanical damage inflicted upon them, with or without any external stimuli. Most of the self-healing materials reported in the literature are based on fossil fuels. As environmental regulations tighten up and industries are focused on making a transition from petroleum refinery to bio-refinery, a need arises to invent, develop, and market new bio-based products for advanced applications. However, it is challenging to synthesize self-healing polymers, especially thermosets and elastomers, from biomass, which are compatible with 3D printing technologies and can easily be reprocessed without degrading mechanical and thermal properties. On the other hand, polymeric materials usually display either high stretchability or high strength. In recent years, many studies have been conducted to resolve the long-standing conflict between strength and toughness, two vital and mutually exclusive mechanical properties, by incorporating nanofillers into the polymer matrices. Nonetheless, uniform dispersion of nanofillers to achieve strong matrix-filler interfacial bonding, which is essential for effective load transfer, is a major challenge in composite engineering.
This thesis reports the development of 3D printable, self-healing elastomers incorporating renewable components, and copolymer based nanocomposites for high performance applications.
In the first study, a self-healable, reprocessable, and inkjet 3D printable elastomer is reported, which is based on a diacrylate monomer synthesized from canola oil and a partially oxidized silicon-based copolymer containing free thiol-groups and disulfide bonds. In an inkjet 3D printing device, both substances are cross-linked via UV-irradiated thiol-ene-click chemistry. The self-healing and recycling attributes of the elastomer are achieved by phosphine-catalyzed disulfide metathesis. The healed and reprocessed elastomers display mechanical properties and thermal stabilities comparable to the original, with self-healing and reprocessing efficiencies of ~86 and ~124%, respectively. Moreover, the elastomer shows excellent thermal stability before and after reprocessing. 5% weight loss temperature was found to be around 350 °C.
In the second part of this thesis, graphene oxide (GO) reinforced poly(styrene-co-methyl methacrylate) is synthesized via in situ bulk polymerization. The monomer ratios are optimized, and the effect of GO concentration on the mechanical and thermal properties of the copolymer are studied. The ultimate tensile strength, failure strain, and storage modulus of the copolymer were increased by 14.6, 15, and 43%, respectively, by adding only 0.1 weight fraction of GO. Furthermore, the thermal stability of the nanocomposites was better than the neat copolymer. -
- Subjects / Keywords
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- Graduation date
- Fall 2020
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.