Cold‐drawing of acetone‐crystallized polyethylene terephthalate

The room‐temperature cold‐drawing behavior of acetone‐crystallized polyethylene terephthalate film has been compared with that of amorphous and heat‐crystallized film. X‐ray diffraction photographs give good resolution in the case of the acetone‐crystallized sample with evidence of molecular orientation in every case. The order of the magnitudes of the yield stresses is acetone‐crystallized < amorphous < heat‐crystallized. Heating of the drawn samples produces disorientation for the amorphous drawn film with an improved resolution of the diffraction photograph for the heat‐crystallized film. It is suggested that the results are in agreement with a picture of a drawing mechanism involving molecular mobility in the amorphous regions and that acetone influences the yield stress by lowering the softening temperature.