DESIGN OF POLYVINYL CHLORIDE/NBR THERMOPLASTIC VULCANIZATES AS EFFICIENT HEAT-TRIGGERED SHAPE MEMORY POLYMERS

ABSTRACT Heat-triggered shape memory polymers, consisting of plasticized polyvinyl chloride (PVC) and 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. Field-emission scanning electron microscope images revealed the uniform distribution behavior of the coordination crosslinked NBR particles within the PVC matrix, forming a characteristic “sea-island” microstructure, whereas the NBR particle sizes ranged 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. A 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 (<15 s) in various shapes. The mass ratio of PVC to NBR also influenced the shape memory properties obviously, with the best-integrated property achieved at the weight ratio of 80/20. Under optimal deformation temperature and recovery temperature, high shape-fixity (>90%) and shape-recovery (>90%) ratios could be achieved. This research provides the insight into the preparation and properties of PVC/NBR TPV as heat-triggered shape memory polymers.