The effects of physical ageing on crazing of polyphenylquinoxaline films

The effects of physical ageing on the crazing of polyphenylquinoxaline (PPQ -E) films were studied. The DSC endothermic peak at the glass transition re gion of the samples was interpreted in terms of the cohesional entanglement theory. The free volume cavity size and free volume intensity of the sampl es were characterized by positron annihilation life spectroscopy. The diffe rence in free volume cavity size and free volume intensity between two samp les reflect the strength and density of cohensional entanglement point. The critical strain for craze initiation and craze stability depended on physi cal ageing of the samples. The relationships between physical ageing and cr azing were interpreted initially.