Functional Nitroxyls in Polypropylene Based Thermoplastic Vulcanizates
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Authors
Bodley, Michael
Date
Type
thesis
Language
eng
Keyword
Nitroxyls , Thermoplastic Vulcanizates , Peroxide Vulcanization
Alternative Title
Abstract
Peroxide vulcanization of polypropylene (PP) based thermoplastic vulcanizates (TPVs) is hindered by PP’s susceptibility to radical degradation. PP degradation occurs through chain scission of tertiary alkyl macroradicals, reducing molecular weight, and negatively effecting TPV blend morphology. Nitroxyl chemistry using acryloyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl (AOTEMPO) was exploited to control the dynamics and rheological outcomes of peroxide polyolefin modifications. PP melt viscosity was partially retained by introducing a competition between macromonomer oligomerization and β-scission. Further improvements were observed when synergizing the polymer-bound acrylate functionality of AOTEMPO, with trimethylolpropane triacrylate (TMPTA) a multifunctional coagent. Resulting TPVs contained smaller, more dispersed crosslinked elastomer particles when compared to peroxide-only formulations, owing to the retention of PP molecular weight.
A follow up investigation into the effects of AOTEMPO on TPV physical property performance was completed for low elastomer content blends (0-20wt%). AOTEMPO formulations provided improved particle dispersion compared to peroxide only formulations, owing to the retention of melt viscosity. These improved particle dispersions led to better impact performance for AOTEMPO formulations over peroxide only formulations. Additionally, AOTEMPO formulations provided improved tensile properties compared to peroxide only formulations, owing to the branched architecture formed during polyolefin modification.
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.