Title page for ETD etd-070799-133604


Type of Document Dissertation
Author Jensen, Robert Eric
URN etd-070799-133604
Title Investigation of Waterborne Epoxies for E-Glass Composites
Degree PhD
Department Chemistry
Advisory Committee
Advisor Name Title
Ward, Thomas C. Committee Chair
Davis, Richey M. Committee Member
Dillard, John G. Committee Member
Riffle, Judy S. Committee Member
Wightman, James P. Committee Member
Keywords
  • waterborne epoxy
  • cooperativity
  • moisture uptake
  • interphase
  • interfacial shear strength
Date of Defense 1999-06-09
Availability unrestricted
Abstract
Research is presented which encompasses a study of epoxies based on diglycidyl ether

of bisphenol A (DGEBA) cured with 2-ethyl-4-methylimidazole (EMI-24) in the presence of the

nonionic surfactant Triton X-100. Interest in this epoxy system is due partially to the

potential application as a waterborne replacement for solvent cast epoxies in E-glass laminated

printed circuit boards. This research has revealed that the viscoelastic behavior of the

cured epoxy is altered when serving as the matrix in a glass composite. The additional

constraining and coupling of the E-glass fibers to the segmental motion of the epoxy matrix

results in an increased level of viscoelastic cooperativity. Current research has determined

that the cooperativity of an epoxy/E-glass composite is also sensitive to the surface chemistry

of the glass fibers. Model single-ply epoxy/E-glass laminates were constructed in which the glass

was pretreated with either 3-aminopropyltriethoxysilane (APS) or 3-glycidoxypropyltrimethoxysilane

(GPS) coupling agents. Dynamic mechanical analysis (DMA) was then used to create master curves

of the storage modulus (E') in the frequency domain. The frequency range of the master curves and

resulting cooperativity plots clearly varied depending on the surface treatment of the glass fibers.

It was determined that the surfactant has surprisingly little effect in the observed trends

in cooperativity of the composites. However, the changes in cooperativity due to the surface

pretreatment of the glass were lessened by the aqueous phase of the waterborne resin.

Moisture uptake experiments were also performed on epoxy samples that were filled with spherical

glass beads as well as multi-ply laminated composites. No increases in the diffusion constant

could be attributed to the surfactant. However, the surfactant did enhance the final equilibrium

moisture uptake levels. These equilibrium moisture uptake levels were also sensitive to the

surface pretreatment of the E-glass.

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