Mechanical and Thermal Properties of a Diglycidyl Ether of Bisphenol-A (DGEBA)–4,4′-Diaminodiphenyl Sulfone (DDS) System Cured under Hydrostatic Pressure

Abstract

Samples of a diglycidyl ether of bisphenol-A (DGEBA)–4,4′-diaminodiphenyl sulfone (DDS) system have been cured under various hydrostatic pressures from atmospheric to 162 MPa of N2 gas at 150°C and characterized by means of dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). The glass transition temperature (Tg) of the pressure-cured samples was found to increase and then decrease with increasing cure pressure. The Tg, determined by DMA, varied from 184°C for samples cured at atmospheric pressure to 205°C for samples cured at 35 MPa, and then to 181°C for samples cured at 162 MPa. The Tg of the pressure-cured samples was also determined by DSC and found to undergo the same trend of that obtained by DMA but at slightly lower temperatures. The storage modulus in glassy state of samples cured at different pressures varies only slightly, but the equilibrium modulus obtained from the rubbery plateau region increased rapidly and reached the maximum at the cure pressure of 35 MPa and then decreased with increasing cure pressure.