The microvoid formation process that takes place during the plastic deformation of fl-form polypropylene (PP) was investigated at different crystallization and drawing temperatures. It was found that the porosity increased with both a higher crystallization temperature and a lower drawing temperature. This fact could be understood in terms of the stability of the fl crystals of the original film. The more stable /3 crystals that formed at a higher crystallization temperature had a lower molecular chain mobility and thus hindered the bulk contraction of the film, while at the same time the volume contraction caused by either a fl-~ or a/3-smectic transformation inside the film enlarged the microvoids at the end, or between the microfibrils
Посилання на статтю:
Microvoid formation process during the plastic deformation of B-form polypropylene / Feng Chu, Tetsuji Yamaoka, Hiroshi Ide and Yoshiharu Kimura // Polymer. – 1994. – Vol 35. – P. 3442-3448.