Studies on relaxation and thermal expansion behavior of polysiloxane-modified epoxy resin

Abstract

Abstract Epoxy network systems based on DGEBA (bisphenol-A-diglycidyl ether) with two kinds of polysiloxane with low molecular weight, ATPS (aminopropyldimethyl-terminated polysiloxane) and PTPS (phenyl-terminated polysiloxane), were prepared and annealed at 175°C. Their physical aging data were curve fitted with the Kohlrausch-William-Watts (KWW) equation and thermal expansion behaviors of both quenched and strained samples were investigated. Results show that curve-fitted ΔH e reflects the relative amount of the “frozen-in” excess free volume in the epoxy network, related to the deviation from equilibrium state. With increase of the ATPS content, both Δl, which was defined as linear dimension drop per millimeter height of sample, and ΔH e decrease; that is, they change in the same direction.