Effect of the addition of chemical blowing agents on the processability of a rigid PVC compound

Abstract

This work deals with the effect of the addition of a combination of two chemical blowing agents (BA), azobisformamide (ABFA) and/or sodium bicarbonate (SBC), on the processability of rigid polyvinylchloride (PVC) using a Brabender torque rheometer. This technique was previously used under conditions bearing no relation to real polymer processing. Our contribution is to overcome this problem and to provide a complementary understanding. It was found that the addition of BA separately leads to the appearance of a new peak following the melting peak on the Brabender torque rheometer process curve. On the other hand, two distinct peaks were shown when both BAs are added together. These peaks correspond to the decomposition of the BA and the expansion of the resulting cells. From this study, the Brabender torque rheometer has proven to be a valuable new tool to follow the stages of decomposition of the BA and the cell expansion within an environmental polymeric resin under real processing conditions.