Effect of environmental atmosphere and stress-loading storage on the intrinsic stress and its distribution in polycarbonate screw cap

The polycarbonate screw cap part had cracking problem during storage, which mechanism needed to be studied. The effect of environmental atmosphere and stress-loading storage on the intrinsic stress and its distribution in polycarbonate screw cap part was investigated in the paper. The analytical results indicated that the intrinsic stress in polycarbonate screw cap had a tendency to decrease slightly or to keep unchanged during room temperature-low humidity (40%RH) storage and room temperature-middle humidity (55-65%RH) storage for 315 days, while had a tendency to decrease obviously during 315 days of high temperature-high humidity (47 degrees C+90%RH) storage. After 300 days of stress-loading storage, the intrinsic stress in polycarbonate screw cap part also decreased obviously, and it might belong to stress relaxation. The distribution of intrinsic stress in polycarbonate screw cap part basically kept unchanged during environmental atmosphere storage and stress-loading storage.