Fracture toughness and properties of plasticized PVC and thermoplastic polyurethane blends

In this work, fracture toughness and properties of blends of plasticized poly(vinyl chloride) (PVC) and thermoplastic polyurethane (TPU) were investigated. Two kinds of TPU with different hardness, i.e. TPU90 (Shore A hardness 90) and TPU70 (Shore A hardness 70) were compared. PVC/TPU90 and PVC/TPU70 blends with variable weight ratio (100/0, 90/10, 80/20, 70/30, 60/40, 50/50, 0/100) were prepared by melt blending. Fracture toughness was investigated using the J-integral by locus method. Blending of TPU with plasticized PVC improved tensile strength, impact strength, abrasion resistance, and thermal stability, with small decline of tensile modulus and hardness. The PVC/TPU blends showed flame retardancy over the composition ranges, regardless of the hardness of TPU, except the PVC/TPU70 of 50/50 composition, in terms of the limiting oxygen index. PVC/TPU70 blends showed higher Jc values and thus higher fracture toughness over the entire composition than PVC/TPU90 blends. For the PVC/TPU70 blends, the SEM micrographs showed clear dimple rupture fracture topology, while the PVC/TPU90 blends did not. (C) 1998 Elsevier Science Ltd. All rights reserved.