Nucleation and overgrowth of PE on PTFE/iPP interfaces

Using an experimental setup with a three-phase intersecting boundary of PTF E/PE/iPP, the nucleation power of PTFE compared to iPP on the PE was studie d by TEM. It was found that the nucleation of the PE on the PTFE interface started at a higher temperature than epitaxial nucleation of the PE onto th e iPP interface. During cooling of the melt, the growth direction of the PE crystalline lamellae changes in a continuous manner from the transcrystall ization direction of the PTFE/PE interface into the heteroepitaxial "crossh atched" orientation of the iPP/PE interface. A (still highly speculative) s elf-assembly of the PE macromolecules at the respective interface just in f ront of the actual crystallization edge is used to explain this observed ph enomenon. (C) 2000 John Wiley & Sons, Inc.