The Deterioration of Impact Properties and Structure of Polycarbonate Aged in H₂SO₄ Aqueous Solutions

The characterization of the impact strength and structure of bisphenol A polycarbonate aged in 65 degrees C H2SO4 aqueous solutions (pH = 4.5) and in distilled water, both at 65 degrees C, was carried out by means of impact testing, Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), Polarizing Microscopy (POM) and Scanning Electron Microscopy (SEM) measurements. The results were as follows: the impact strength increased a little (from 71 to 76.3 kJ/m(2)) after being aged 1 day in the H2SO4 aqueous solution. Microvoids were formed on the surface of the PC in both the aqueous solution and distilled water aging, and the size and number of the microvoids increased substantially with the increase of aging time. The glass transition temperature showed a slight decrease after aging. In both liquids, the degradation mechanism was ascribed to the hydrolysis of ester groups in both aqueous solutions aging. However, the hydrolysis rate of PC aged in hot water was higher than that of the sample aged in the H2SO4 aqueous solution in the first day of aging. In addition, a ductile failure to brittle failure transition was observed for both H2SO4 solution and hot water aging.