A modified ethylene-vinyl acetate copolymer material and a method for preparing the same

Abstract

This invention relates to a modified ethylene-vinyl acetate copolymer material and a method for preparing its EVA film. The material uses ethylene-vinyl acetate copolymer as the continuous phase, introduces high-density polyethylene and linear low-density polyethylene to construct a composite structure, and achieves interphase connection through polar grafted polyethylene. Simultaneously, it incorporates orientation-controlled fillers with specific aspect ratios to form a multi-level synergistic system. During processing, the intermediate structure formed in the system is rapidly fixed through the coordinated control of process parameters such as shear rate, shear time, rapid cooling under negative pressure, and directional traction, resulting in a non-uniform orientation distribution along the film thickness direction. By establishing the relationship between shear strength, polar component dosage, and filler dosage, continuous transmission of structural evolution is achieved. The resulting EVA film exhibits good stability in terms of crystallization behavior, heat-sealing performance, and mechanical properties, featuring high heat-sealing strength, a wide heat-sealing window, and good structural continuity, making it suitable for the packaging industry.

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