INFLUENCE OF THERMAL STABILIZERS ON DIFFUSION OF POLY(EPSILON-CAPROLACTONE) IN POLY(VINYL CHLORIDE) POLY(EPSILON-CAPROLACTONE) BLENDS

The influence of thermal stabilizers on the poly(epsilon-caprolactone) (PCL) diffusion in poly(vinyl chloride) (PVC)/PCL blends was studied with the addition of various concentrations of dibasic lead phthalate and dibutyltin dilaurate. The rate of PCL diffusion was followed by di fferential scanning calorimetry and IR spectroscopy in three series of experiments: the migration of PCL at the surface of the sample; the e xtraction of PCL in a fluid surrounding the sample; and the sorption o f liquid PCL in the blend. In the last two series, mass losses and mas s uptakes were measured as a function of time. As compared to the blen d without additive, dibutyltin dilaurate induces an increase of the PC L rate of diffusion whereas dibasic lead phthalate gives a decrease. T hese trends are explained by: first, the formation of an associative c omplex between dibutyltin dilaurate and PVC, which can compete with th e PVC/PCL interactions in the blend and thus favor the PCL migration; and, second, the modification of the T-g of the blend induced by the a ddition of a third component, which can modify the diffusion rate by c hanging the free volume fraction at the diffusion temperature. T-g dec reases slightly in the presence of dibutyltin dilaurate but increases with dibasic lead phthalate. (C) 1996 John Wiley & Sons, Inc.