Surface degradation of unsaturated polyester resin in Xe artificial weathering environment

Unsaturated polyester (UP) resin samples were exposed to artificial weathering environment produced by a xenon lamp light exposure and weathering equipment for different time intervals. The change of appearance, optical property, chemical structure and surface microstructure before and after exposure in this environment was monitored by spectrophotometer, gloss meter, Specular Reflection Fourier Transform Infrared (SR-FTIR) spectroscopy and three-dimensional digital microscope. The results showed that the surface of UP resin turned darker and yellower in the whole weathering stage. Gloss decreased with increasing aging time due to the increase of surface roughness. SR-FTIR results showed that ester bonds in polymeric chains broke in the aging process. With increasing aging time, small voids can be observed on UP surface and expanded gradually to cracks.