Growth kinetics in melt-crystallizing polymers: a possible role of nucleating agents

The effect of low molecular weight dopants (nucleating agents) on the basal surface tension σe of freely growing lamellae in melt-crystallizing polymers is analyzed in terms of a statistical thermodynamic model. The latter is based on a lattice description of the basal interfacial regions developed previously for pure, compressible melt-crystallized polymers (Physica A 287 (2000) 105). Nucleant molecules diffusing out of regions being about to crystallize are responsible of a σe reduction which practically depends only on the average nucleant concentration and (via lamellar thickness) on the undercooling at which crystallization is driven. Growth rate data obtained by calorimetry from nucleated poly(ethylene oxide) and polyethylene are well described by the theory.