分子量对超高分子量聚乙烯性能的影响研究

超高分子量聚乙烯(UHMW—PE)塑料合金具有优异的物理和机械性能,能替代金属在离心泵和轴承等机械领域中的广泛应用。超高分子量聚乙烯的分子量对其物理机械性能有着很大影响。本重点研究了分子量对超高分子量聚乙烯的耐磨性、拉伸强度、洛氏硬度、冲击强度等的影响规律,为UHMW—PE的工业应用提供理论依据。     

超高分子量聚乙烯塑料轴承设计研究

超高分子量聚乙烯具有优异的物理和机械性能,其机械强度高、硬度大、摩擦系数低、尤其耐磨性能极佳,在所有工程塑料中名列前茅。因而用超高分子量聚乙烯替代金属作为轴承材料,其应用前景必定十分广阔。在分析材料性能的基础上,对超高分子量聚乙烯塑料轴承设计原理进行了研究,为工业化生产提供理论依据。     

超高分子量聚乙烯的医学应用及降解研究现状

阐述了超高分子量聚乙烯在医学应用中的应用现状，介绍了国内外超高分子量聚乙烯的降解研究进展现状，揭示了降解对于超高分子量聚乙烯在医学应用中的影响，并展望了对降解的进一步研究方向。     

超高分子量聚乙烯塑料承设计研究

超高分子量聚乙烯具有优异的物理和机械性能,其机械强度高,硬度大,摩擦系数低,尤其耐磨性能极佳,在所有工程塑料中名列前茅,因而用超高分子量聚乙烯替代金属作为轴承材料,其应用前景必定十分广阔,在分析材料性能的基础上,对超高分子乙烯资料轴承设计原理进行了研究,为工业生产提供理论依据。     

超高分子量聚乙烯异型材挤出工艺的有限元分析

设计了超高分子量聚乙烯异型材的导轨挤出流道,应用有限元软件模拟超高分子量聚乙烯熔体和聚丙烯熔体这两种聚合物熔体在同一流道内的流动规律,获得流道内部的压力场、速度场和温度场。研究表明,所设计的异型材导轨挤出流道对两种聚合物熔体压力分布的影响明显,对速度分布和温度分布的影响基本一致。最后通过试验验证了超高分子量聚乙烯异型材导轨挤出流道设计的合理性。     

超高分子量聚乙烯结晶度对生物摩擦学性能的影响

研究了不同结晶度对超高分子量聚乙烯力学和生物摩擦学性能的影响.将超高分子量聚乙烯加热至130 ℃并保温4 h后,分别在液氮中快速冷却和加热炉中缓慢冷却,以此来改变其结晶度.利用差示扫描量热法(DSC)测试了样品的结晶度,并研究了不同结晶度对超高分子量聚乙烯的硬度、小型冲击性能、抗划痕性能和生物摩擦学性能的影响.结果显示,在加热炉中缓慢冷却的试样获得较高的结晶度,而在液氮中快速冷却的试样则具有较低的结晶度,分别为61.9%和53.2%;较高结晶度的超高分子量聚乙烯具有较高的硬度和抗拉强度,较强的抗剪切和抗划痕性能;小牛血清润滑下的往复式摩擦磨损试验结果显示,较高结晶度的超高分子量聚乙烯的摩擦因数和磨损率较低.     

用考虑了粘弹性的有限元法对塑料齿轮进行计算分析

使用ABAQUS有限元软件,考虑了塑料的粘弹性,对超高分子量聚乙烯齿轮进行了计算分析。计算了超高分子量聚乙烯齿轮齿根应力、应变随时间的变化关系以及与其配对的钢齿轮的齿根应力、应变与时间变化关系等。     

橡胶轴承的特点、设计与应用研究

橡胶作为轴承材料已获广泛应用，橡胶轴承在现代工业技术领域中显示出越来越重要的作用，超高会子量聚乙烯，硬质橡胶都是橡胶轴承，轴互的优良材料，在分析材料性的基础上，对超高分子量聚乙烯轴承进行了设计研究，为工业化生产提供理论依据，同时对超高分子量聚乙烯轴承的工业结果进行了总结。     

模拟深海环境下超高分子量聚乙烯及其复合材料的摩擦磨损行为研究

使用自行设计的高压摩擦磨损试验机考察超高分子量聚乙烯及其碳纤维、玻璃纤维填充复合材料在模拟深海环境下的摩擦磨损性能,并研究海水静压对材料吸水率、化学稳定性以及塑化作用的影响规律。研究表明,海水静压对边界润滑段的摩擦因数影响很小,但显著增大了弹流段的摩擦因数;吸水过程增大了超高分子量聚乙烯及其复合材料在静压下的磨损率,其原因可能在于静压增大了材料的吸水率,影响了材料的化学稳定性并加速了材料的塑化;碳纤维、玻璃纤维均有助于提升超高分子量聚乙烯在海水静压下的耐磨性能,其中,碳纤维填充高分子量聚乙烯在海水静压下的耐磨性能优于玻璃纤维填充高分子量聚乙烯,其磨损率基本不受海水静压影响。     

超高分子量聚乙烯齿轮在超弹性条件下的有限元分析

超高分子量聚乙烯是一种高弹性体材料，作为齿轮材料在承受载荷时，其变形具有非线性、大应变的特点。采用超弹性的Arruda—Boyce模型来模拟超高分子量聚乙烯齿轮在工作状态下的应力分布，计算结果表明：超高分子量聚乙烯齿轮的最大应力出现在齿根部位。     

The application of a zero wear model to metal/ polyethylene sliding pairs

The application of a zero wear model to polyethylene/metal pairs has been examined using a rider-on-a-flat geometry. It was found that the model enabled the number of passes to reach the zero wear limit to be predicted but that deviation between the theory and experiment occurred for large numbers of passes.It was found that both high density polyethylene and ultrahigh molecular weight polyethylene gave the same behavior in the zero wear region. This is in contrast to the non-zero wear region in which high density polyethylene wears much faster than ultrahigh molecular weight polyethylene. The sources of difficulty in predicting the non-zero wear behavior from the behavior in the zero wear region are examined.     

Exploratory investigations on the structure dependence of the wear resistance of polyethylene

A relatively simple hemisphere-on-flat sliding wear tester was devised for screening samples of polyethylene prior to their trial in total joint simulators and ultimately in implanted total joint replacements. Testing was done in bovine serum and wear debris was recovered quantitatively by a method previously devised. The debris, wear surfaces and wear rates were all consistent with previous work, including simulators and clinical materials. It was found that the wear rate increases by a factor of more than 30 when the molecular weight is decreased from 2 × 10⁶ to 5 × 10⁵, that irradiation in doses typical of sterilization procedures improves wear resistance, as does reduction in fusion defect size in ultrahigh molecular weight material, and that chemical cross-linking improves wear resistance in high density polyethylene but still not to the level of the ultrahigh molecular weight material. In material with a molecular weight typical of total joint replacements, an exponential dependence of wear rate on load was found.     

A study of the wear of some materials in connection with total hip replacement

Failure of total hip prostheses due to wear is examined. It is concluded that wearing out of these devices should not be a problem. However, it is desirable to look for materials of improved wear resistance due to possibilities of long-term response to wear debris.A series of experiments is described to evaluate the wear resistance of candidate materials on an annular wear tester. The results indicate that the wear resistance of ultra high molecular weight polyethylene may be improved by increase in molecular weight, by irradiation or by the use of fillers. Pyrolytic carbon containing silicon is also a good candidate.     

Quantification of Wear Rates and Plastic Deformation on Mobile Unicompartmental UHMWPE Tibial Knee Inserts

Experimental wear testing is an essential step in the evaluation of unicompartmental knee prostheses; the major mechanisms that dominate the wear of conventional ultra high molecular weight polyethylene tibial knee menisci are the sub-surface cracking and delamination that induce particle release by abrasion/adhesion and subsequently periprosthetic osteolysis. The aim of this study was to determine whether plastic deformation affects the wear of the polymer and to measure the magnitude of these effects. Wear test was performed using a displacement-control knee wear simulator with “three-plus-one” stations, in accordance with the ISO 14243-3/2. A state-of-the-art coordinate measuring machine was used to quantify the volumetric mass loss of the mobile knee polyethylene menisci as well as creep/plastic deformations. The volumetric wear measured by this method was compared to that measured by the gravimetric method. Raman spectroscopy showed morphology changes induced by mechanical stress in both the upper and lower surfaces of the menisci. The amorphous content increased at expenses of the crystalline orthorhombic content, which generally decreased in all menisci. A slight orthorhombic → monoclinic phase transformation occurred upon mechanical stress. Plastic deformation appeared as the main factor affecting the trend of the spectroscopic markers and thus the morphology degradation.     

Tribology of total artificial joints.

The tribology of total artificial replacement joints is reviewed. The majority of prosthesis currently implanted comprise a hard metallic component which articulates on ultra high molecular weight polyethylene surface. These relatively hard bearing surfaces operate with a mixed or boundary lubrication regime, which results in wear and wear debris from the ultra high molecular weight polyethylene surface. This debris can contribute to loosening and ultimate failure of the prostheses. The tribological performance of these joints has been considered and a number of factors which may contribute to increased wear rates have been identified. Cushion bearing surfaces consisting of low elastic modulus materials which can articulate with full fluid film lubrication are also described. These bearing surfaces have shown the potential for greatly reducing wear debris.     

The friction and wear behavior of irradiated very high molecular weight polyethylene

The friction and wear behavior of gamma irradiated very high molecular weight polyethylene has been studied for radiation doses of 20 to 1000 MRad. For tests run at low loads the effect of irradiation is to increase the friction coefficient and the wear factor. As the load is increased the friction coefficient decreases and the wear factor remains constant. At a critical load there is an abrupt increase in the wear factor. However, further increase in the load leads to a decrease in the wear factor to about the original value. This wear behavior is quite different from that shown by unirradiated polyethylene and is connected to changes in structure resulting from the temperatures generated during sliding.     

On the pressure dependence of the wear of ultrahigh molecular weight polyethylene

The wear of polyethylene in bovine serum was evaluated as a function of load and molecular weight. The range and distribution of contact loadings simulated those which exist in currently available total hip and total knee prostheses. The wear increased exponentially with load at constant molecular weight. An increasing molecular weight parametrically displaced the exponential curve to higher loads, lowering the overall rate. It is proposed that the behavior of these materials be described in terms of a critical pressure-velocity product although the specific mechanisms for wear acceleration are not known in this case.     

不同润滑条件对塑料合金轴承摩擦磨损性能的影响

用MPV 2 0 0型摩擦磨损试验机对超高分子量聚乙烯 (UHMW PE)塑料合金轴承在水润滑介质不同含沙量的条件下进行了摩擦学性能测定 ,分别考察了载荷、速度以及运行时间等对合金轴承摩擦学性能的影响。为水润滑合金轴承的实际应用提供理论指导。     

Tribological Behavior of UHMWPE Reinforced with Graphene Oxide Nanosheets

In this article, a series of graphene oxide (GO)/ultrahigh molecular weight polyethylene (UHMWPE) composites are successfully fabricated through an optimized toluene-assisted mixing followed by hot-pressing. The mechanical and tribological properties of pure UHMWPE and the GO/UHMWPE composites are investigated using a micro-hardness tester and a high speed reciprocating friction testing machine. Also, the wear surfaces of GO/UHMWPE composites are observed by a scanning electron microscope (SEM), to analyze the tribological behavior of the GO/UHMWPE composites. The results show that, when the content of GO nanosheets is up to 1.0 wt%, both the hardness and wear resistance of the composites are improved significantly, while the friction coefficient increases lightly. After adding GO, the tribological behavior of the GO/UHMWPE composites transforms from fatigue wear to abrasive wear associated with the generation of a transfer layer on the contact surface, which efficiently reduced the wear rate of the GO/UHMWPE composites.