Date of Award

Spring 2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Polymer Science and Engineering

Committee Chair

Dr. Jeffrey S. Wiggins

Committee Chair School

Polymer Science and Engineering

Committee Member 2

Dr. Sarah E. Morgan

Committee Member 2 School

Polymer Science and Engineering

Committee Member 3

Dr. Sergei I. Nazarenko

Committee Member 3 School

Polymer Science and Engineering

Committee Member 4

Dr. Derek L. Patton

Committee Member 4 School

Polymer Science and Engineering

Committee Member 5

Dr. Yoan C. Simon

Committee Member 5 School

Polymer Science and Engineering

Abstract

Linear backbone segments of traditionally linear thermoplastic polymers, like poly(aryl ether ketones) (PAEKs), may be chemically incorporated into aerospace epoxy-amine thermoset matrices in the form of hybrid diamines. Previous research by Misasi proved 5 mole percent incorporation of 1,3-phenylenebis((4-(4-aminophenoxy)phenyl)methanone) (AEK-134) not only increased the ultimate compressive strain of a baseline 4,4'-methylenebis(N,N-bis(oxiran-2-ylmethyl)aniline) (TGDDM)/4,4’-diaminodiphenyl sulfone (4,4’-DDS) network by 40%, but also simultaneously increased compressive Young’s modulus and yield strength by 20%.1 However, the implementation of AEK-134 in aerospace prepreg manufacture was precluded by its high melting temperature and high reactivity with oxirane.

In the present work, aryl ketone ether (AKE)-based hybrid diamines were investigated for reduced reactivity with oxirane and for potential mechanical property enhancement of a TGDDM/4,4’-DDS baseline matrix. Alternate hybrid diamine synthetic pathways were also explored in order to improve yields, crude purities, product throughputs, and reaction efficiency. Computational simulation was utilized to relate hybrid diamine backbone structure to matrix mechanical property enhancement.

Eaton’s Reagent (PPMA) afforded intermolecular acylations of aromatic substrates with carboxylic acids and amine acid salt. 1H NMR was used to determine a previously unestablished (and age-dependent) ratio of PPMA volume required for full conversion of carboxylic acid (rc = 0.635 mLPPMA/mmolCOOH). ((1,4-Phenylenebis(oxy))bis(4,1-phenylene))bis((4-aminophenyl)methanone) (AKE-144) and ((1,4-phenylenebis(oxy))bis(4,1-phenylene))bis((3-aminophenyl)methanone) (AKE-143) were synthesized with greater than 90% crude yields and purities at a product throughput of nearly 500 g per 2.8 L of Eaton’s Reagent. Hybrid diamines 1,3-phenylenebis((4-(4-aminophenoxy)phenyl)methanone) (AEK-134) and 1,4-phenylenebis((4-(4-aminophenoxy)phenyl)methanone) (AEK-144) were synthesized in a similar fashion on a 250 mL scale. The effects of amine melting temperature and pKa on the rheological processing curves with TGDDM were also investigated. Using a 4,4’-DDS/3,3’-DDS eutectic alloy and a series of monoamines and diamines with varied pKa, interdependencies between amine melting temperature and pKa with rheological processing curves were established. AKE-144 and AKE-143 did not enhance Young’s modulus, yield stress or strain or ultimate strain in a TGDDM/4,4’-DDS network. Radial distribution functions determined that a very unique “horseshoe”-like conformation and strong hydrogen bonds between 1.5 and 2.2 Å may be tied to mechanical property enhancement.

Available for download on Thursday, May 10, 2029

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