REACTIVE BLENDING OF BIOAFFINE POLYESTERS THROUGH FREE-RADICAL PROCESSES

Blends of poly-epsilon-caprolactone (PCL) and poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate) (PHBV) containing 4 mol-% of hydroxyvalerate were prepared by mixing the two polymers in the presence of either dicumylperoxide (DCPO) at 160-degrees-C or dibenzoylperoxide (DBPO) at 100-degrees-C. Similarly, blends were obtained by mixing the two polymers without any peroxide added. The blends were prepared in two complementary compositions, namely 70 wt.-% PCL/30 wt.-% PH BV and 30 wt.-% PCL/70 wt.-% PHBV, respectively. Also pure polymers were reacted with DCPO at 160-degrees-C in the same way as the blends. Thermal (DSC), mechanical (tensile tests) and SEM analyses were performed on the blends and on the pure polymers. Significant differences were found in the chemical-physical characteristics of blends with and without peroxides as well as in blends prepared at low and high temperatures.