Spontaneous crystallization of the planar zigzag form of syndiotactic polypropylene at 0 °C

The crystallization of the planar zigzag form is spontaneously induced at 0 °C for syndiotactic polypropylene which has been obtained by nuclear magnetic resonance spectroscopy and X-ray scattering methods. Mechanical stress, which was always applied to samples in the conventional method to obtain such crystals, is not essential to induce this type of crystallization. When the temperature of films is increased to room temperature after holding them at 0 °C, crystals are produced in addition but this crystallization is significantly suppressed by the presence of crystals with the planar zigzag conformation formed previously at 0 °C.