Design of Polyvinyl Chloride/Nitrile-Butadiene Rubber Thermoplastic Vulcanizates as Efficient Heat-triggered Shape Memory Polymers

ABSTRACT Heat-triggered shape memory polymers, consisting of plasticized polyvinyl chloride (PVC) and nitrile-butadiene rubber (NBR), were prepared by dynamic vulcanization. A model describing the shape memory behavior of PVC/NBR thermoplastic vulcanizate (TPV) has been proposed. The favorable interfacial compatibility between PVC and NBR serves as the foundation for the noteworthy mechanical and shape memory properties of TPV. The field-emission scanning electron microscope (FE-SEM) images revealed the uniform distribution behavior of the coordination crosslinked NBR particles within the PVC matrix, forming a characteristic "seaisland" microstructure while the NBR particle sizes ranging from 1∼8 μm. The mechanical results indicate that the continuous PVC phase plays a primary role in determining the mechanical properties of the prepared TPV. The strong interfacial interaction between the two phases is crucial for maintaining the temporary shape and storing the recovery driving force. The shape memory behavior of PVC/NBR TPV was examined, demonstrating rapid recovery in various shapes (<15 s). The mass ratio of PVC to NBR also influenced the shape memory properties obviously, while the best-integrated property achieved at the weight ratio of 80/20. Under optimal deformation temperature (Td) and recovery temperature (Tr), the high shape fixity ratios (>90 %) and shape-recovery ratios (>90 %) could be achieved. The research provides the insights into the preparation and properties of PVC/NBR TPV as heat-triggered shape memory polymers.