分子量对UHMWPE熔体破裂程度的影响

Effect of Molecular Weight on Melt Fracture Degree of UHMWPE

采用不同分子量的国内外2种系列超高分子量聚乙烯(UHMWPE)作为原料,加入一定量的流动助剂,通过注塑机对空高速高压注射制备得到UHMWPE“喷射流”粒子,研究了分子量对UHMWPE“喷射流”粒子的孔隙微观结构、粒径分布和平均粒径的影响。结果表明,随着UHMWPE分子量的增加,其熔体流动速率(MFR值)减小,流动性变差,在高速剪切下,越容易发生熔体破裂,形成的“喷射流”粒子的孔隙结构增多,粒径分布更加均匀,且粒子平均粒径值变小。在相同的条件下,国产SLL⁃8型UHMWPE物料的MFR值较小,由其制备的“喷射流”粒子的孔隙结构较好,熔体破裂的程度较大,粒径平均值较小,最适合制备UHMWPE微孔材料。

Ultra⁃high molecular weight polyethylene(UHMWPE)with different molecular weights from home and abroad were used as raw materials.UHMWPE mixed with a certain amount of additives was injected into the air through an injection molding machine at high speed and high pressure to prepare UHMWPE“Jet Flow”particles.The effects of different molecular weights on UHMWPE melt fluidity and the microstructure,particle size distribution and average particle size of UHMWPE“Jet Flow”particles were studied.The results demonstrated that with the increase of molecular weight of UHMWPE,the melt flow rate(MFR)decreased and the fluidity became worse.Under high shear rate,the higher the molecular weight of UHMWPE,the easier it was for the melt fracture,the more pore structure of the“Jet Flow”particles formed,the more uniform the pore size distribution,and the smaller the average particle size value.Under the same conditions,the domestic SLL⁃8 UHMWPE material had the smallest MFR,and the“Jet Flow”particles prepared by it had the best pore structure,the largest melt fracture degree,and the smallest average particle size,which was the most suitable for preparing UHMWPE microporous materials.