Synergistic Effect of Knitted/Woven Hybrid Structure on the Shape Memory Performance and Mechanical Durability of Polymeric Composites

Abstract

ABSTRACT The knitted‐fabric reinforced shape memory polymeric composites (SMPC) have large recoverable deformation and limited mechanical properties, whereas woven‐fabric reinforced SMPC possess good mechanical properties and limited recoverable deformation. In this work, six laminated SMPCs with different lay‐up sequences were prepared using weft plain knitted fabrics (K), rib knitted fabrics (R), woven fabrics (W) and the epoxy‐based shape memory polymer (SMP) to study the synergistic effect of the knitted/woven hybrid structure on the shape memory performance and mechanical durability of SMPC. The results show that SMPCs have a high shape fixation ratio and a good shape recovery ratio. When the knitted fabrics are laminated in the outer layers and the woven fabrics are in the middle layers, the shape recovery properties of SMPCs are good, and the SMPCs after shape memory cycles have a low damage area of interface debonding. The KKKK SMPCs obtain the smallest recovery force, and the WWWW SMPCs have the largest recovery force of up to 4.4 N. Furthermore, after 1, 5, and 10 shape memory cycles, the flexural strength and modulus of SMPCs generally decrease, whereas the fracture strain of SMPCs increases. The addition of knittedstructure to wovenructure can improve the residual strength ratio of SMPCs after shape memory cycles. The hybridized lay‐up of knittedstructure and wovenructure endows the SMPCs with optimized shape memory performance, mechanical properties, and mechanical durability after shape memory cycles. Finally, the finite element simulation of SMPCs during U‐bending was performed to help discuss the mechanism.