Abstract:

Ultra-high molecular weight polyethylene (UHMWPE) is a commonly used high-properties polymer. Due to the influence of high viscosity, its processing and application are greatly restricted. The uniformity of the additive dispersion during processing is considered to be the key for the preparation of high-properties UHMWPE composites. Polyethylene glycol (PEG) has high fluidity and is widely used to improve the viscosity behavior of UHMWPE. But the dispersion effect of the added phase in the composite material has an important influence on the performance of the UHMWPE composites. UHMWPE/PEG composites with different proportions were prepared by dry powder mixing, solution mixing, and melt extrusion blending. Based on the melt tensile test, the influence of blending mode and ratio on the entanglement behavior and properties of UHMWPE was studied, and the microscopic mechanism of the disentanglement of UHMWPE molecular chain was analyzed by the presence of PEG. The results show that the addition of PEG increases the plasticity of UHMWPE, reduces its internal chain entanglement density, and increases the mobility between molecular chains. Although the crystallinity of the material is improved to certain extent, it does not significantly change the melting temperature. Among the three mixing methods, when 5% PEG is added, the untangling effect of dry powder mixing and extrusion mixing is more obvious, and the chain entanglement density is reduced by about 26%.

Key words: ultra-high molecular weight polyethylene, blend, untangling mechanism, mechanical properties, interface structure

摘要：

超高分子量聚乙烯（UHMWPE）是常用的高性能聚合物。由于高黏度的影响，极大地限制了其加工成型与应用。聚乙二醇（PEG）具有高流动性，被广泛用来改善UHMWPE的流变行为，但复合材料中添加相的分散效果对材料的性能有重要影响。采用干粉混合、溶液混合、熔融挤出共混等方式制备了不同配比UHMWPE/PEG复合材料。基于熔融拉伸实验研究了共混方式及配比对UHMWPE缠结行为及性能的影响。结果表明，PEG的加入降低了复合材料的链缠结密度。三种混合方式中，加入5%PEG时干粉混合与挤出混合解缠作用较明显，链缠结密度均降低26%左右。

关键词: 超高分子量聚乙烯, 混合, 解缠结, 力学性能, 界面结构