Growth of craze phase and control of void diameter by Laplace-pressure in crazing films

The pore size of voids in crazed polypropylene (PP) was controlled by Laplace-pressure. Void diameter decreased and dropped out at 100 degrees lower temperature from the melting point of PP. These crazed films are adequate to a battery separator for the application. In this work, we attempted to extend the craze phase for high porosity. New voids were generated and grown around existing voids, and the number of voids per unit area was increased while maintaining the average void diameter. Healing temperature of the crazed PP films by Laplace-pressure was 60 degrees C in air, however 110 degrees C-135 degrees C in electrolytic solutions of propylene carbonate, dimethyl sulfoxide, and diethyl carbonate. This craze healing temperature depended on the interfacial tension. (C) 2018 The Japan Society of Applied Physics