Crystallization of isotactic polypropylene in a temperature gradient

The crystallization of isotactic polypropylene films was investigated in co nstant and in time-dependent temperature gradients. The temperature gradien t influences a spherulitic pattern as well as an internal structure of sphe rulites. The gradient can accelerate conversion of the melt into spherulite s although it has no effect on spherulitic nucleation. The acceleration of the local conversion results from a contribution of spherulites nucleated i n colder parts of a sample. The observed effects intensify with the increas e of the temperature gradient and they are also enhanced by a higher crysta llization temperature.