超高分子量聚乙烯冲击能量吸收机理研究

Study on Absorbed Impact Energy of UHMW-PE

在HDPE分子量8万～327万内,选择6种不同分子量试件,在室温到液氮温度范围内,系统测量各试件冲击强度(σ_i)随温度变化关系曲线。用SEM观察各试件的冲击断口形貌,用DSC和WAXD测量各试件的结晶度,并计算出HDPE分子量和缠结点密度之间关系曲线。通过结构—形态—性能之间关系研究表明,UHMW-PE分子量在150万处σ_i出现极大值,是结晶度和缠结点密度变化的共同结果,并对UHMW-PE冲击能量吸收机理进行初步探讨,得出分子链之间缠结是影响σ_i的关键因素。

In this paper, the effect of molecular weight (M) on the Charpy impact strength of ultrahigh molecular weight polyethylene (UHMW-PE) was studied at different temperatures. M of UHMW-PE changed systematically from M=8.00×104 to 3.27×106. The influence of M on crystallinity and fractograph was investigated by means of WAXD, D, DSC and SEM. The curve of entanglement density versus M was calculated by equation. UHMW-PE samples were prepared by compareusing molding and sintering.The experiment and theoretical analysis indicate at first the impact strength of samples increases with increasing M, and the sample of M=1.50 ×106 exhibites the maximum impact strength. Then,the impact strength of samples decreases with increasing M. The maximum impact strength of sample (M=1.50×106) is due to sudden change of crystallinity and entanglement density.As a summary, it is entanglement that brings about the excellent impact strength of UHMW-PE.