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ETD_PhD dessertation_Vahab Solouki.pdf (5.65 MB)

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Polyurethane (PU) Nanocomposites; Interplay of Composition, Morphology, and Properties

Solouki Bonab, Vahab
http://orcid.org/0000-0003-4391-6476
http://rave.ohiolink.edu/etdc/view?acc_num=case1542634359353501

Abstract Details

2019, Doctor of Philosophy, Case Western Reserve University, Macromolecular Science and Engineering.
Thermoplastic polyurethanes (TPUs) are among the most versatile engineering polymers. The presence of hard and soft segments on their backbone and specific hydrogen bond interactions between the hard segments, provide TPUs with outstanding engineering properties whilst rendering them as very complex systems to study. Knowledge of morphology – property relationship is essential for TPUs since their thermal and mechanical behavior are directly dictated by their complicated morphology. Having in mind the need to improve TPU applications at high temperatures, TPU was optimized to reach its top performance. Exceeding the neat TPU performance limitations is possible through incorporation of nanofillers and formation of strong 3D networks. Nanocomposites were obtained through in-situ polymerization of TPU and carbon nanofillers with different geometries (carbon nanotubes (CNTs), carbon nanostructures (CNS) and graphene nanoplatelets (GNP)). By investigating nanocomposites with different nanofiller geometries, it became apparent that CNT and CNS are suitable for mechanical reinforcement while GNP is potentially the best candidate for tribological properties. For mechanical reinforcement, the goal is to form a strong percolated nanofiller network at the lowest possible filler content. It was found that addition of 0.3wt% straight CNTs or 0.1wt% of CNS extended TPU application window for more than 20oC and decreased creep strain up to 60 and 40% at 100 and 120oC, respectively. Due to their branched morphology, CNS proved to be more efficient in mechanical reinforcement than CNTs. The design strategy for nanocomposites tailored for tribological properties is not based on GNP percolated networks. Crosslinked polyurethane systems were also investigated. By activating tansesterification and transcarbamoylation dynamic exchange reactions, dynamic crosslinked networks (vitrimers) could undergo reprocessing, reshaping and self healing. Furthermore a microwave assisted fast healing (30 folds faster) strategy by the addition of small amounts (0.05 wt%) CNTs was explored. The dynamic crosslinked network concept was also applied to PU thermoset waste. We demonstrated that unrecyclable thermoset PUs can be reprocessed. The developed recycling methodology relies on suppling a proper catalyst that could activate dynamic exchange reactions in thermoset and turn thermoset into a vitrimer.
Ica Manas-Zloczower (Advisor)
David Schiraldi (Committee Member)
Donald Feke (Committee Member)
Gary Wnek (Committee Member)
232 p.
Engineering; Nanotechnology; Polymer Chemistry; Polymers
Thermoplastic polyurethane; Nanocomposite; Percolation; Carbon nanotube, Carbon nanostructure, Graphene; Mechanical properties; Creep resistance; Tribology; Dynamic crosslinked network; Vitrimer; Self healing; Recycling; thermosets; Microwave

Recommended Citations

Citations

  • Solouki Bonab, V. (2019). Polyurethane (PU) Nanocomposites; Interplay of Composition, Morphology, and Properties [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1542634359353501

    APA Style (7th edition)

  • Solouki Bonab, Vahab. Polyurethane (PU) Nanocomposites; Interplay of Composition, Morphology, and Properties. 2019. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1542634359353501.

    MLA Style (8th edition)

  • Solouki Bonab, Vahab. "Polyurethane (PU) Nanocomposites; Interplay of Composition, Morphology, and Properties." Doctoral dissertation, Case Western Reserve University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1542634359353501

    Chicago Manual of Style (17th edition)

case1542634359353501
556
© 2019, some rights reserved.Creative Commons License Polyurethane (PU) Nanocomposites; Interplay of Composition, Morphology, and Properties by Vahab Solouki Bonab is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.