Excellent toughness of rigid polyvinylchloride at low temperature improved by polycarbonate-polydimethylsiloxane block copolymer

Rigid polyvinylchloride (PVC) is widely used in various fields, but its low impact strength at low temperature limits its deep application in some cold regions. This work utilizes polycarbonate-polydimethylsiloxane block copolymer (PC-b-PDMS) to toughen PVC. PDMS segment has extremely low glass transition temperature (−126°C) and PC segment has a good compatibility with PVC, which proved by the Fourier transform infrared and dynamic mechanical thermal results. For verifying toughening effect of PC-b-PDMS, the impact behavior at 23°C, 0°C and −30°C of PVC/PC-b-PDMS blends is investigated. The impact strength of modified PVC increases from 2.09 to 95.00 kJ·m⁻² at 23°C, and the significant brittle-ductile transition occurs at 10 phr PC-b-PDMS. At −30°C, 25 phr PC-b-PDMS makes brittle-ductile transition appear and impact strength increased by 17 times. According to impact-fractured morphology, PDMS acts as stress concentrator in PVC/PC-b-PDMS and produces a lot of cavities, crazes, and shear bands to consume impact energy, exhibiting good toughening effect. Overall, the PC-b-PDMS with excellent toughening effect is a promising alternative to traditional toughening agents, showing great promising application prospects in low-temperature toughening of the rigid PVC products.