Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


ROHM_ETD.pdf (4.71 MB)

ETD Abstract Container

Abstract Header

Thermoplastic Polyurethane: A Complex Composite System

Rohm, Kristen Nicole
http://orcid.org/0000-0002-1672-7007
http://rave.ohiolink.edu/etdc/view?acc_num=case1625604511143102

Abstract Details

2021, Doctor of Philosophy, Case Western Reserve University, Macromolecular Science and Engineering.
The step polymerization reaction between diisocyanates and diols results in a tremendously functional material with wide-ranging applications including medical devices and sealants, known as thermoplastic polyurethane (TPU). The microphase separation of urethane-rich hard segments (HS) and hydrocarbon soft segments (SS) provide TPU with the unique morphology responsible for its elastomeric properties. The structure-property relationships of TPU have been understood in terms of either a rubber-like material where HS-rich regions act as crosslink points or a nanocomposite where hard regions are the reinforcing agent. In both views, attempts to model the mechanical behavior based on morphology are hampered by the difficulty in determining parameters that describe the morphology from the chemical composition. The distribution of HS block length and the attractive hydrogen bonding forces make predicting the morphology using block co-polymer theory imprecise, especially for low HS content (HSC) TPUs. Furthermore, TPU has typically been viewed as a binary system with a hard phase dictated by the HSC and a soft phase whose properties are only dependent on the diol type and molecular weight. The first part of this thesis challenges the binary view of TPU through an experimental and modeling investigation. An analytical micromechanical model, the Eshelby double inclusion model, was used to evaluate the observed mechanical behavior of a series of polyester TPUs with increasing HSC, a series of polyether TPUs softened by triols in the SS, and a series of polyester TPUs softened by triol chain extenders. The model was used to probe the mechanical reinforcement contribution from morphological parameters. The TPU morphology was modeled as a composite of HS-rich “hard particles” and a SS-rich “soft matrix”, with the necessity of a third, intermediary phase, the “interphase” evaluated based on experimental results. The second part of the thesis goes beyond neat TPU by preparing multi-material TPU composites for improved functionality. The processing-property relationships of TPU composites with graphite, graphene, and polytetrafluoroethylene are investigated. The importance of the secondary phase’s aspect ratio, dispersion, and interfacial area are discussed in the context of different processing techniques including in situ polymerization and batch mixing and for their value as solid lubricants.
Ica Manas-Zloczower (Advisor)
Donald Feke (Committee Member)
Michael Hore (Committee Member)
Gary Wnek (Committee Member)
212 p.
Polymers
thermoplastic polyurethane; composite mechanics; dispersion; thermal analysis; polymer processing;

Recommended Citations

Citations

  • Rohm, K. N. (2021). Thermoplastic Polyurethane: A Complex Composite System [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1625604511143102

    APA Style (7th edition)

  • Rohm, Kristen. Thermoplastic Polyurethane: A Complex Composite System. 2021. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1625604511143102.

    MLA Style (8th edition)

  • Rohm, Kristen. "Thermoplastic Polyurethane: A Complex Composite System." Doctoral dissertation, Case Western Reserve University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1625604511143102

    Chicago Manual of Style (17th edition)

case1625604511143102
280
© 2021, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.