PTFE PhD Proposal: Tom Wyatt

Date: Tuesday, 25th November 2014

Location: MRDC 4404

Time: 1:45 PM

Committee:

Dr. Donggang Yao (MSE) (advisor)

Dr. Yulin Deng (IPST)

Dr. Anselm Griffin (MSE)

Dr. Satish Kumar (MSE) 

Dr. Youjiang Wang (MSE)

 Title:  Oligomer spin-solvent gel-fiber spinning

Abstract: 

Successful processing of polymer molecules into well oriented fiber structures with minimal defects is difficult because the thermodynamically favorable state is a random coil, and molecular relaxation perpetually opposes efforts to extend and orient polymer molecules. Many polymers with unique chemical and physical properties cannot be exploited to their full potential because their tensile strength and modulus in the random, entangled configuration is insufficient for typical engineering applications. Polymer fibers from gel-spinning processes have achieved tensile moduli approaching the theoretical values, and the strongest fibers created by man are produced through gel-spinning; however, a fundamental approach to gel-spin high-strength fibers from polymers with different chemistries is not known. Currently, the gel-spinning process is limited to PVOH, PAN, UHMWPE.

This research proposes a fundamental process design for producing high-strength polymer fibers from most semi-crystalline polymers. The proposed process design emphasizes the use of oligomers (or multimers) from the same chemical source of the polymer as a solvent for gel-spinning. An oligomer/multimer solvent typically is less toxic and flammable than conventional small molecule solvents and its boiling point can be adjusted, leading to greatly improved processing flexibility. Furthermore, by selecting an oligomer solvent, the perilous search for conventional solvents for typical solvent resistant polymers such as PTFE, POM, and PPS is eliminated. The oligomer solvent will be shown to fundamentally fulfill the requirements of the ideal gel-spinning spin-solvent by forming a solution at high temperature and promoting gelation up cooling.

The proposed process design will be validated by gel-spinning two polymers that are difficult to process using conventional techniques. It will be shown that the fibers produced from the proposed process are significantly stronger and stiffer than their melt or solution spun counterparts. By employing the proposed gel-spinning process, high strength fibers with unique physical and chemical properties can be produced to fulfill demanding applications where known fibers would fail.