制备工艺对硅烷交联超高分子量聚乙烯综合性能的影响

Processing Effect on Comprehensive Performance of Silane Cross-linked Ultrahigh Molecular Weight Polyethylene

本文在传统硅烷交联方法的基础上,结合超高分子量聚乙烯(UHMWPE)的特点,对接枝和交联工艺分别进行改进:接枝过程中,在UHMWPE出现亚稳性的工艺条件下,利用柱塞挤出在较低温度和压力下完成了UHMWPE的硅烷接枝过程的连续操作;交联过程中,预先在硅烷接枝UHMWPE中添加合适的产水剂一水合草酸钙,利用模压过程中产水剂在聚合物内部产生水从而实现UHMWPE硅烷接枝料的原位水解缩合交联反应,省去传统硅烷交联聚烯烃需经过水煮或蒸汽处理的过程。研究了工艺改进后所制备的硅烷交联UHMWPE的凝胶含量、热性能以及机械性能随产水剂用量的变化规律,材料的综合性能更优异。

Based on traditional cross-linking technology using silane and characteristics of ultra-high molecular weight polyethylene（UHMWPE）, improved silane cross-linking and grafting of UHMWPE was performed in this paper. The improvements included ram extrusion in the metastability state of UHMWPE to achieve the silane-grafted UHMWPE under conditions of low temperature and pressure. Water-carrying agent CaC_2O_4·H_2O pre-added in the silane-grafted UHMWPE released water at high temperature under compression molding. Therefore, the in situ hydrolysis condensation and cross-linking of the silane grafted UHMWPE was realized due to the water release in the cross-linking process. Compared with traditional silane cross-linking technology, the need of placing the silane-grafted polymer in hot water was obviated in the process reported here. Characterization of gel ratio, thermal and mechanical properties of the cross-linked UHMWPE reveals that the gel ratio increases with increasing of CaC_2O_4·H_2O content, and both thermal stability and rigidity increase observably and the tensile properties reduce slightly even at higher level of cross-linking degree. The comprehensive performances of the cross-linked UHMWPE are improved.