Mechanical, Water-swelling, and Morphological Properties of Water-swellable Thermoplastic Vulcanizates Based on Polyvinyl Chloride/Crosslinked Sodium Polyacrylate/Chlorinated Polyethylene Blends

A novel water-swellable rubber (WSR) was prepared by dynamically vulcanizing polyvinyl chloride (PVC)/chlorinated polyethylene (CPE) blends where a crosslinked poly(sodium acrylate) (CPNaAA) was used as a super water-absorbent resin and dispersed in the CPE rubber. The mechanical, water-swelling, and morphological properties were investigated. The results showed that the dynamically vulcanized PVC/CPNaAA/CPE blends exhibited obvious elastomeric behavior and could be considered as thermoplastic vulcanizates (TPVs). The PVC/CPNaAA/CPE TPVs showed strong water-swelling ability, with the water-swelling ratio of the PVC/CPNaAA/CPE TPV with 30/60/70 weight ratio reaching 2400% at 200h immersion. Moreover, compared with the first water-swelling behavior, the second and third water-swelling behaviors of the TPVs showed significantly improved water-swelling ratio and a remarkable decrease of weight loss. Morphological study showed that the interface interaction between the CPNaAA and CPE was weak. The CPNaAA particles in the blends could be separated and even be pulled out from the matrix under tensile stress, leading to the formation of suspended CPNaAA particles on the fracture surface of PVC/CPNaAA/CPE TPVs. The surface of the dried TPVs was rough and significant cavities could be found. The dynamic mechanical properties were investigated and the TPVs showed the typical Payne effect.