中文摘要：

目的从微观结构层面上对材料改性研究提供理论支持。方法以EVOH为基体,与PP,HDPE进行改性共混,形成EVOH/PP,EVOH/HDPE共混体系,在此基础上运用Materials Studio 5.0计算机分子模拟软件构建超高压下包装材料的分子动力学模型,利用Discover Analysis和Amorphous Cell Analysis分别分析计算氧气分子在EVOH,EVOH/PP,EVOH/HDPE混合晶胞中的浓度分布以及各分子的内聚能密度（CED）。结果氧气分子在改性共混材料中扩散能力明显减弱,在1.2~1.4 nm处,EVOH（800 MPa下）中出现2个点划线峰,而EVOH/PP（800 MPa下）中仅出现1个点划线峰、EVOH/HDPE（800 MPa下）中仅出现1个虚线峰;超高压处理使EVOH,EVOH/HDPE,EVOH/PP的CED随压力增大而增加,EVOH/HDPE由276.2 J/m3（0.1 MPa）增至340.344 J/m3（800 MPa）,EVOH/PP由70.8 J/m3（0.1MPa）增至240.5 J/m3（800 MPa）,且EVOH/HDPE、EVOH/PP材料的CED均低于EVOH。结论超高压处理能够影响所选包装材料的微观结构,进而影响材料的阻隔和力学性能。

英文摘要：

The aim of this work was to provide theoretical support for material modification from the aspect of microstructure. Based on EVOH with good barrier property, blending of EVOH with PP or HDPE resulted in the formation of EVOH/PP and EVOH/HDPE. On this basis, Materials Studio 5.0 computer molecular simulation software was applied to construct molecular dynamics model for the packaging material under high pressure processing （HPP）, while Discover Analysis and Amorphous Cell Analysis were used respectively to calculate the concentration profile of oxygen within the mixed crystal cells of EVOH, EVOH/PP and EVOH/HDPE and the corresponding cohesive energy density （CED）. The oxygen permeability of EVOH/PP and EVOH/HDPE was significantly weakened. EVOH, EVOH/PP and EVOH/HDPE had 2 dotted line peaks,1 dotted line peak and 1 dashed line peak respectively in the range of 1.2-1.4 nm under 800 MPa. The CED of EVOH, EVOH/HDPE and EVOH/PP increased with the increasing pressure of HPP, increasing from 276.2 J/m^3 （0.1 MPa） to 340.344 J/m^3 （800 MPa） for EVOH/HDPE, from 70.8 J/m^3 （0.1 MPa）to 240.5 J/m^3 （800 MPa） for EVOH/PP. TheCED values of EVOH/HDPE and EVOH/PP were both lower than that of EVOH. In conclusion, HPP affected the microstructure of the selected packaging material and thus its barrier and mechanical properties.