화학공학소재연구정보센터
Polymer Engineering and Science, Vol.36, No.6, 869-878, 1996
A New Method to Evaluate Solvent Stress Cracking
The effect of crystallinity on the crazing process in isotactic polypropylene (i-PP) was investigated by using a new static crazing experiment. Strips of i-PP films are stressed in glass cones, which are placed into a series of solvents. Characterization of the films was performed by hot-stage optical microscopy, scanning electron microscopy, wide-angle X-ray scattering, differential scanning calorimetry, and contact angle goniometry. The affinities of the solvents for the polymer were investigated by dynamic solvent uptake measurements. Crazing experiments revealed that both the sample preparation and the solvent choice play an important role in the crazing process. A "good" solvent is shown to be a "bad" crazing agent, whereas an intermediate solvent behaves as a "good" crazing agent. Two opposite processes are shown to take place : appearance of void and solvent-induced crystallization.