人工关节用各向同性自增强聚乙烯共混物的制备与性能研究

Improving mechanical properties of UHMWPE implants without the sacrifice of the excellent wear and fatigue resistance of UHMWPE has been the focus of current research in this area. In this work, crosslinked UHMWPE is proposed to blend with LMWPE aiming to obtain PE blend with desirable fluidity, and then UHMWPE/LMWPE blend is processed under oscillation shear stress field to form the oriented shish-kebab self-reinforced superstructure in LMWPE phase, finally cold compressing is employed with the intention of fully retaining the self-reinforced superstructure and making it evenly distribute in all direction, aiming to achieve suitable artificial joint specimens with homogenized superior comprehensive performance in each direction. Through systematic study of the rheological properties of UHMWPE/LMWPE blend, modulation of the self-reinforced superstructure of UHMWPE/LMWPE blend under flow field as well as the properties of product by cold compressing, we can reveal the relationship between processing field - morphology and structure - performance of UHMWPE/LMWPE self-reinforced material, providing theoretical guidance and technical support for the preparation of high-performance artificial joint implants.

在不降低超高相对分子质量聚乙烯（UHMWPE）人工关节制品优异的耐磨性、抗蠕变性的前提下，提高其力学性能是目前该领域研究的重点，也是难点。本项目拟采用微交联UHMWPE 与低相对分子质量聚乙烯（LMWPE）共混，获得加工性能良好的UHMWPE/LMWPE共混物，并在注塑加工的保压阶段施加剪切流动场，在LMWPE中形成shish-kebab取向自增强结构，然后采用固态成型在充分保留自增强结构的同时使其在各个方向上结构分布均匀，使制品在各个方向上的综合力学性能得到显著同步增强。通过系统研究微交联UHMWPE /LMWPE体系流变性能，加工流动场下UHMWPE/LMWPE共混物自增强结构的调控，固态成型制品的性能，揭示UHMWPE/LMWPE共混物自增强材料加工外场-形态结构-性能间的关系，为制备高性能人工关节植入体提供理论指导与技术支持。

以调控超高分子量聚乙烯（UHMWPE）等生物材料的多层次形态结构为手段，本项目提出了仿生人工关节材料的注塑成型加工技术路线和获得高强度高耐磨人工关节/骨替代材料的设计思路。通过引入低分子量聚乙烯（LMWPE）改善UHMWPE的熔体流动性和加工性，同时引入辐照交联的UHMWPE（xUHMWPE）限制PE分子链在LMWPE和UHMWPE两相间的扩散运动，制备了UHMWPE达50 wt%的可注塑成型共混物，并施加强剪切流动场诱导大量自增强结构的形成，最终获得高拉伸强度（81.2 MPa）和高冲击强度（35.2 kJ m–2）的自增强UHMWPE材料。提出了采用超低分子量聚乙烯（ULMWPE）进一步提高可熔体加工共混体系中UHMWPE的含量至90 wt%，以强剪切流动场诱导的高规整互锁串晶为高效自增强结构，实现注塑制品的高强度（拉伸强度达65.5 MPa）和高耐磨性（摩擦系数低至7.1 mg/MC），更同时具有良好的细胞相容性。结合ULMWPE的良好流动性和xUHMWPE高热氧稳定性，通过震荡剪切注塑成型制备了高强高耐磨的xUHMWPE/ULMWPE/UHMWPE (95/4.9/0.1)共混体系，发现剪切流场能有效促使高规整取向片晶的形成，实现共混物的高强度（拉伸强度62.8 MPa）与高抗氧化能力（氧化指数0.7），而且获得了显著改善的熔体加工性。开发了双腔注塑成型工艺技术，成功将乙烯-丙烯酸共聚物（EVA）和聚酰亚胺66（PA66）/羟基磷灰石（HA）一体化制备成多层次的仿软骨/骨关节，其中，EVA作为“软骨”提供良好力学性能和生物相容性并抵抗摩擦，而PA66/HA作为“骨”结构提供有力的强度支撑和优异的生物活性与生物相容性。