Effect of polycarbonate-polydimethylsiloxane block copolymer and two commercial toughening agents on the flame retardancy and smoke emission of rigid polyvinyl chloride

In this work, different test methods were used to investigate the flame retardancy and smoke emission of polyvinyl chloride (PVC) toughened with polycarbonate-polydimethylsiloxane block copolymer (PC-b-PDMS) and two other commercial toughening agents. The oxygen index result and heat release curves in the cone calorimetry test showed that toughened PVC has reduced flame retardancy compared to unmodified PVC. However, the vertical combustion test showed that all samples have achieved the highest flame retardant rating, indicating that the flame resistance of these toughened PVC is still adequate for use. In terms of smoke emission, the results of the cone calorimetry test and the smoke density test showed a significant difference. In the smoke density test, it was found that PVC toughened with PC-b-PDMS has less smoke generation in the early stage of combustion. In the cone calorimetry test, the total smoke production was lower for PVC and significantly higher for toughened PVC. This difference was mainly due to the different test conditions of these two tests.