HETEROGENEOUS NUCLEATION AT INTERFACES IN ISOTACTIC POLYPROPYLENE

Investigations of the efficiency of various nucleating additives for isotactic polypropylene showed that heterogeneous nucleation can exhibit a double character. In addition to conventional heterogeneous nucleation arising because of interaction of the solid surface of the additive with the crystallizing polymer, it is necessary to take into account heterogeneous nucleation at interfaces between the crystallizing polymer and gas or vapour pores and bubbles. Minute holes or pores produced by such gases or vapours present in polymer are able to act as efficient nucleating centres. © 1969.