Composition and Structure of a Stress Relieving Removable Epoxy Resin.

摘要

The aqueous modification of polyol modified anhydride cured diglycidyl ether of bisphenol A exhibits properties of a brittle solid when subjected to an impulse stress,and properties of a viscous fluid when subjected to a steady state stress. This behavior is markedly different from the nonaqueous system. Early attempts to understand the nature of the change in properties and the physical mechanism involved have not been completely successful. Previous studies of the aqueous modification of polyol modified anhydride cured diglycidyl ether of bisphenol A have verified that the water significantly accelerates the anhydride ring opening reaction compared to the nonaqueous system. It had been postulated that the accelerated ring opening reaction facilitated the formation of a noncrosslinked low molecular weight polymer. In an attempt to confirm this hypothesis,the elucidation of the structure was undertaken. High-speed gel permeation chromatography indicated two things: (1) the material is noncrosslinked because it dissolves in solvent,and (2) the highest molecular weight material formed is approximately 2500. The material was shown to be composed of eight components. The three smallest components are unreacted starting materials and only 4percent of the overall system. The molecular weight range of the five remaining components is 500to 2400,with 80percent of the material being of an average molecular weight of 1900. The five remaining components have been identified by the use of infrared analysis,gas chromatography-mass spectrometry,and elemental analysis. Verification of the structures was accomplished via saponification of the products and identification of the fragments.