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
- moisture uptake
- interfacial shear strength
Date of Defense 1999-06-09 Availability unrestricted AbstractResearch 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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