Natural and artificial heterogeneous nucleation in polymer crystallization

Abstract An outline is given of heterogeneous nucleation as the main starting point for crystallization of unoriented polymer melts and solutions. The influence of temperature history on nucleation is discussed. As little is known about naturally occurring nucleants, the nature of several types of artificial nucleating agents is described. Potential mechanisms of heterogeneous nucleation are discussed against the background of various theoretical models. Experimental methods of measurement of nucleation density or of nucleation frequency may give some indication as to which mechanism is operative. The main conclusion is that heterogeneous nucleation is governed by “active sites” in the surface of the nucleants.