Date of Award

Spring 2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Polymer Science and Engineering

Committee Chair

Jeffrey S. Wiggins

Committee Chair School

Polymer Science and Engineering

Committee Member 2

William L. Jarrett

Committee Member 2 School

Polymer Science and Engineering

Committee Member 3

Sergei I. Nazarenko

Committee Member 3 School

Polymer Science and Engineering

Committee Member 4

Derek L. Patton

Committee Member 4 School

Polymer Science and Engineering

Committee Member 5

Robson F. Storey

Committee Member 5 School

Polymer Science and Engineering

Abstract

The understanding of thermoset cure has, traditionally, been limited to the analysis of a single degree of cure value obtained via techniques such as dynamic scanning calorimetry (DSC). These analyses limit the scope of understanding of network development during cure. The continued development of rapid cure matrix chemistries necessitates the advancement of analytical techniques capable of quantifying how thermal cure profiles influence crosslinked network architectures throughout cure. This dissertation investigates and elucidates the mechanisms of polymer network growth through glassy epoxy/diamine thermoset to improve the way network growth is tracked and inform the role of cure protocol on network formation. The primary tool used to study the effect of cure protocol on network development was Real-Time Fourier Transform Infrared Spectroscopy in the near infrared wavelength region (RT-NIR). Through the course of this work great strides were made in the considerations needed to accurately monitor functional group conversion in RT-NIR when using variable temperatures. A temperature dependence on the absorbance of NIR overtones was identified and a methodology to correct for the effect was developed. The improved RT-NIR analytical technique was applied to study how a thermal ramp rate affects the network formation pathway of high glass transition temperature (Tg), glassy thermosets during cure. It was determined that highly crosslinking networks based on the tetrafunctional epoxide tetraglycidyl-4,4'-diaminodiphenylmethane (TGDDM) have their pathway of network formation effected by the rate if thermal ramp to a constant cure temperature. Finally, the material properties of epoxy diamine networks cured with varied thermal ramp rate was studied. This dissertation improved upon the application of RT-NIR as a quantifiable characterization tool to accurately study the formation of epoxy/diamine networks during cure. The RT-NIR technique was then applied to study a cure protocol effect on the pathway of network formation during cure of epoxy/diamine thermosets.

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