Non-isothermal crystallization kinetics of ethylene-vinyl acetate copolymer and ethylene-vinyl acetate copolymer/butadiene rubber thermoplastic vulcanizate

Abstract

The non-isothermal crystallization kinetics of both pure ethylene-vinyl acetate copolymer (EVA) and EVA/butadiene rubber (BR) thermoplastic vulcanizate (TPV) which was prepared through dynamic vulcanization were investigated via differential scanning calorimetry (DSC). The mechanism of non-isothermal crystallization was analyzed using the Avrami model modified by the Jeziorny method, along with the Ozawa and Mo methods. The results demonstrated that the non-isothermal crystallization behavior of both EVA/BR TPV and pure EVA could not be accurately described by the Ozawa method. In contrast, the Jeziorny and Mo methods provided a more precise representation of the crystallization behavior. Data analysis revealed that EVA exhibited a faster crystallization rate compared to EVA/BR TPV. In contrast, the initial crystallization temperature of EVA was lower than that of the EVA/BR TPV. In conclusion, BR served as a nucleating agent in EVA/BR TPV, facilitating the nucleation of the EVA phase. However, due to the steric hindrance effects, the EVA crystal growth process was hindered by the existence of BR phase.