pH Effect on epoxy-anhydride water aging

Abstract

Hydrothermal aging of an epoxy-anhydride network was investigated to elucidate the degradation effects of the external medium pH. For that reason, gravimetric analysis, Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and modulated differential scanning calorimetry (MDSC) were carried out. For each studied pH, degraded materials showed two values of glass transition temperature suggesting a homogeneous process. Both FTIR and GPC results exhibited signals related to the presence of hydrolyzed network fragments at long times for pH 4 and 7 and at very short times for pH 13. Indicating that at pH 13 both bulk and surface degradation coexist.