Non-isothermal Crystallization Kinetics Behavior of Ethylene-vinyl Acetate Copolymer and Ethylene-vinyl Acetate Copolymer/Nitrile Butadiene Rubber/Liquid Nitrile Butadiene Rubber Thermoplastic Vulcanizates Crosslinked with a Coordination System

Abstract

Thermoplastic vulcanizates (TPVs) based on ethylene-vinyl acetate copolymer (EVA)/nitrile butadiene rubber (NBR)/liquid nitrile rubber (LNBR) were prepared using a dynamic vulcanization method with a copper sulfate (CuSO₄) coordination cross-linking system. The microstructures of EVA/NBR TPV and EVA/NBR/LNBR TPV were analyzed using field emission scanning electron microscopy (FE-SEM). The mechanical properties and non-isothermal crystallization kinetics of EVA/NBR/LNBR TPV, EVA/NBR TPV and pure EVA were investigated using a universal testing machine and differential scanning calorimetry (DSC), respectively. The experimental results demonstrated that the incorporation of LNBR enhanced the mechanical properties of the EVA/NBR TPV significantly. The size of the crosslinked NBR particles were refined with the incorporation of LNBR in TPV, which influenced the non-isothermal crystallization behavior of the EVA phase. Data analysis revealed that the crystallization behavior could be characterized by the Jeziorny and Mo methods effectively. The NBR phase was found to promote nucleation of the EVA matrix while simultaneously inhibiting the growth of EVA crystals. The existence of LNBR in TPV further enhanced the nucleation-promoting effect, while the influence on weakening the inhibition of crystal growth was limited.