The origin of heteroepitaxy in the system of uniaxially oriented isotactic polypropylene and polyethylene

The epitaxy of polyethylene (PE) on oriented and -form of isotactic polypropylene (PP) at different crystallization temperatures and rates have been investigated. The result shows that the epitaxy of PE on -form of PP does not differ from that on the -form of PP. The epitactic alignment of the PE lamellae on the PP films becomes more perfect with higher crystallization rates of PE. The epitaxy of PE on - or -form of PP does not occur at crystallization temperatures higher than 123 °C. A nucleation controlled process for the alignment of the PE is proposed.