Deformation and aging of quenched polypropylene

The physical properties, i. e., yield stress and stress‐strain curve of the quenched (“smectic”) form of polypropylene have been shown to be time dependent at room temperature. The yield stress increases linearly with the logarithm of film age. No changes in the x‐ray diffraction pattern, infra‐red spectrum, electron diffraction pattern or morphology have been observed corresponding to this change in physical properties. A molecular mechanism is proposed which will explain this again process. Spherulites of the quenched form have been found to deform affinely when drawn. In contrast to this, slow cooled films show complete destruction of internal spherulite (lamellar) order, indicating a complex mechanism of deformation.