面向人工关节用UHMWPE模塑料冲击韧性的影响因素

Influence Factors of the Impact Toughness of Ultra-high Molecular Weight Polyethylene Molding Compounds for Artificial Joints

人工关节用模塑料的冲击韧性要求达到180 kJ/m^(2),随着人工关节使用寿命需求的提高,对作为人工关节垫片上游材料的超高分子量聚乙烯(UHMWPE)的韧性提出了更高的要求。本文选用不同分子量(w)的树脂粉料,从粉料结构和加工方式的角度对UHMWPE的增韧原因进行探讨。发现特殊的粉料结构带来了更高的冲击韧性。通过对结晶相、非晶相和中间相的比例分析知道晶区的大小及分布和中间相含量会影响制品的冲击韧性。等温结晶这种后处理方式,能够明显增加样品的韧性。研究发现等温结晶提高冲击韧性的主要原因是用于传递应力的中间相含量提高,起到了提高能量吸收的作用。两个角度均论证了具有高中间相含量的制品具有更高的冲击韧性。研究结果为发展高韧性的人工关节用UHMWPE模塑料提供了有益参考。

The impact toughness of molding compounds for artificial joints is required to reach 180 kJ/m^(2).The ultra-high molecular weight polyethylene(UHMWPE)is the upstream material of the artificial joint spacer.With the increasing demands for the service life of artificial joints,the toughness of UHMWPE has been put forward with higher requirements.In this paper,the toughening reasons of UHMWPE were studied by using different molecular weight(w)resin powders from the perspectives of powder structures and processing methods.It is found that the special virgin powder structure brings higher impact toughness.By analyzing the ratios of crystalline,amorphous and intermediate phases,the size and distribution of crystalline regions as well as the intermediate phase content influence the impact toughness of the products.The post-processing method of isothermal crystallization could significantly increase the sample toughness.It is found that the main reason of the impact toughness increased via the isothermal crystallization is mainly due to the content increase of intermediate phases used for the stress transfer.Intermediate phases improve the efficiency of energy dispersion.Both perspectives demonstrate higher impact toughness of products with higher intermediate phase content.The results provide a useful reference for the developments of high toughness UHMWPE molding compounds for artificial joints.