不同流场对聚乙烯蜡/UHMWPE体系结构与性能的影响

Influence of Different Flow Fields on the Structure and Properties of PE-wax/UHMWPE Composites

选取低分子量聚乙烯蜡(PE-wax)作为解缠结助剂,研究不同流场对超高分子量聚乙烯(UHMWPE)缠结程度的影响规律,分别利用推拉混炼仪与转矩流变仪对PE-wax/UHMWPE进行熔融共混,研究不同加工时间下拉伸流场与剪切流场对复合体系的微观结构与宏观性能的影响。结果表明,在剪切流场作用下,随着塑化混炼时间的增加,体系缠结度逐渐增加,复合体系的拉伸性能呈现先上升后下降的趋势。在拉伸流场的作用前期,UHMWPE初生态粒子规整的分子链结构被破坏,缠结程度升高,其塑化混炼效率高于剪切流场;而在拉伸流场的作用后期,UHMWPE分子链解缠结速率高于缠结速率,缠结程度下降,结晶度与熔点升高,样品的可拉伸性提高。

Low-molecular-weight polyethylene wax(PE-wax)was selected as disentanglement aids to study the influence of different flow fields on the degree of entanglement of ultra-high molecular weight polyethylene(UHMWPE).The PE-wax/UHMWPE was melt blended by push-pull mixer and torque rheometer,respectively,and the effects of the elongational flow field and the shear flow field on the microstructure and macroscopic properties of the composite under different processing times were studied.The results show that under the action of shear flow field,as the plasticizing and mixing time increases,the degree of entanglement of the composite gradually increases,and the tensile properties of the composite show a trend of increasing first and then decreasing.In the early stage of processing under the elongational flow field,the regular molecular chain structure of the UHMWPE nascent particles is destroyed,the degree of entanglement is increased,and the plasticizing and mixing efficiency is higher than that of the shear flow field.In the later stage of processing under the elongational flow field,the disentanglement rate of UHMWPE molecular chain is higher than the entanglement rate,the degree of entanglement decreases,the crystallinity,melting point and the elongation at break of the sample increases.