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  • [会议] 亚浓溶液中超高分子量聚乙烯链缠结初始研究
    超高分子量聚乙烯UHMWPE(Ultra-high molecular weight polyethylene)在亚浓溶液中链缠结初始状态研究采用如下共混体系:(1)聚乙烯蜡,可将聚乙烯蜡考虑为一种"溶剂",为消除了本身链缠结的基体,聚乙烯蜡具有比聚乙烯缠结分子量Me更小的分子量;(2)UHMWPE具有远大于聚乙烯缠结分子量Me的分子量。共混物中各分子链的动力学行为以及微结构的研究主要借助于流变学方法和显微光学结合实现。流变学和形态学研究结果表明,当UHMWPE的质量分数,W2,高于0.84wt%(临界交叠浓度的4倍)后,UHMWPE分子链缠结的初始状态开始出现。由于共混伴随着强剪切的过程,共混物在结构上呈现出非均相性行为,大量UHMWPE分子链的运动单元尺寸变大,在聚乙烯蜡基体中以丝状物(直径在100纳米左右)形式发生扩散。与此同时,共混体系的分子链和缠结结构都经历了向均相化方向转变的过程,直至达到热力学稳定状态。
    关键词: 超高分子量聚乙烯;链缠结;扩散
  • [会议] 高效制备超高分子量聚乙烯用钛系催化剂的研究
    超高分子量聚乙烯(UHMWPE)是一种线型结构的热塑性工程塑料。它的分子结构和普通高密度聚乙烯完全相同,普通高密度聚乙烯的分子量较低,约在5~30万,而UHMWPE的分子量大于100万,具有HDPE及其它一些工程塑料无可比拟的独特性能。本研究通过对传统的Ziegler-Natta催化剂上引入吸电子配体(L),制备了新型的高活性MgCl2负载钛系Ziegler-Natta催化剂,并将该催化剂应用于制备UHMWPE,经研究发现,引入吸电子配体的新型催化剂活性明显高于传统MgCl2负载钛系Ziegler-Natta催化剂,并且催化活性随着配体的吸电子能力的提高而升高,同时,新型催化剂所制备的UHMWPE具有更高的分子量。不仅如此,吸电子配体的引入还提高了原始催化剂的氢调敏感性,使新型催化剂更具工业化前景。
    关键词: 超高分子量聚乙烯;新型催化剂;高活性
  • [会议] Static andDynamic Behaviors of Extruded Low-Density Polyethylene and Ultra-High Molecular Weight Polyethylene
    Thepolyethylene is ofunique predominance in light armor applications.The mechanical properties ofextruded polymers are strongly affected by their molecular structures and distribution.Therefore,twotypicaldifferenttypes of extrudedpolyethylene:low-density polyethylene(LDPE)and ultra-high molecular weightpolyethylene(UHMWPE)werechosenin thisstudy to experimentally investigate the dependency of molecule structures towardsmechanical properties of polyethylene over a wide range of strain rate from 0.001 s~(-1)up to3300s~(-1).The static anddynamic material testsrevealed thatextruded UHMWPE showed a much more obvious strain-hardening effect than that ofLDPE,in addition,it is of an extraordinary higher elongation and stress at failure in Quasi-static tensile tests,and much higher yield stress at SHPB tests.Furthermore,Cowper-Symonds model wasemployed to predict the strain rate effect and in good agreement with the experimental results.It indicates that UHMWPEperforms abettermechanicalbchaviorunderhigh strainratesdeformationthanLDPE;hence,the extruded UHMWPE is more amenable to large deformation and high high-speed impact conditions,benefits from its long molecular chains and few brancbed chains.
    关键词: ultra-high molecular weightpolyethylene;low-density polyethylene;extruded polyethylene;molecular structure;mechanical behavior;impact
  • [会议] 丙烯酸甲酯在超高分子量聚乙烯纤维上的γ射线辐射接枝研究
    采用预辐射接枝的方法研究了丙烯酸甲酯(MA)单体在超高分子量聚乙烯(UHMwPE)纤维表面的接枝聚合反应。考察了吸收剂量、单体浓度、接枝聚合反应温度对接枝率的影响。结果表明UHMWPE纤维接枝MA的接枝率较高,最高可达约200%,接枝率随吸收剂量、单体浓度、反应温度升高而增加。用红外光谱法分析了接枝前后纤维官能团的变化,通过扫描电镜观察了接枝前后纤维表面的形貌。
    关键词: 超高分子量聚乙烯纤维;丙烯酸甲酯;辐射接枝;红外光谱法;表面形貌
  • [会议] 具有单一活性中心性质的Ziegle-Natta催化剂在UHMWPE专用料制备中的应用
    超高分子量聚乙烯(UHMWPE)是一种分子具有线型结构的综合性能优异的热塑性工程塑料,具有其它塑料无可比拟的优异的耐冲击、耐磨损、自润滑性、耐化学腐蚀、耐核辐射性等性能。但是由于其非常高的分子量特殊的结构,UHMWPE加工非常困难,严重限制了其推广应用,目前普遍是通过添加助剂实现其加工,但不可避免会牺牲产品性能。催化剂技术可以控制聚合物链结构、分子量和分子量分布以及聚合物的原生态形貌,通过催化剂技术改造UHMWPE树脂结构有可能成为提高其加工性能的重要途径。
    关键词: UHMWPE;single-site;Ziegle-Natta;catalyst;application
  • [会议] SiC填料改性UHMWPE复合材料的摩擦磨损性能
    将不同质量分数的碳化硅(SiC)粉料与超高分子量聚乙烯(UHMWPE)粉料共混制备SiC/UHMWPE复合材料,并将其与GCr15轴承钢配副,通过实验研究了SiC质量分数对UHMWPE复合材料摩擦磨损性能的影响及其磨损机制,并使用分子动力学模拟对复合材料分子间粘附机理和影响因素进行了深入探讨。结果表明:SiC的加入对UHMWPE材料表面硬度影响并不明显但其摩擦系数显著增大;当SiC质量分数为5wt%时,复合材料表现出较小的摩擦系数和优异的抗磨性能,30wt%SiCUHMWPE复合材料磨损机制由弹塑性变形磨损转变为三体磨粒磨损为主导。SiC与UHMWPE分子间的粘附机理表现为非键范德华力吸附,环境温度的变化对粘附性能影响不大,β-SiC晶体生长方向上的(111)晶面对UHMWPE分子的吸附能力最弱,易导致磨损过程中SiC填料聚积和磨损表面微裂纹的产生。
    关键词: 超高分子量聚乙烯(UHMWPE);碳化硅(SiC);复合材料;摩擦磨损;分子动力学模拟
  • [会议] Bioceramics are not Bioinert: The Role of Oxide and Non-Oxide Bioceramics on the Oxidation of UHMWPE Components in Artificial Joints
    This present research is aimed at understanding the influence of Zirconia-Toughened Alumina (ZTA) and Silicon Nitride (Si_3N_4) on Ultra-High Molecular Weight Polyethylene (UHMWPE) acetabular liners. Bioceramic femoral heads were systematically tested against UHMWPE in controlled environment according to static/load-free coupling in hydrothermal environment, pin-on-ball wear testing, and hip-simulator wear testing. In addition, a retrieved ZTA femoral head has been analyzed and results have been compared to the simulations. Experimental results from X-ray photoelectron (XPS), cathodoluminescence (CL), Raman and Fourier-Transformed Infrared spectroscopy suggest that, despite conventional notions imply that bioceramics are inert, the surface chemistry of bioceramics was relevant to the oxidation rate of polyethylene liners. Non-biointertness could either be advantageous or disadvantageous toward polyethylene oxidation. The main reason resides in the peculiar chemical interactions between polyethylene and different bioceramics; more specifically, it depends on the direction of oxygen flow at the interface between the ceramic and the polymer. ZTA femoral heads were found to release a non-negligible amount of oxygen moieties from their surfaces, thus accelerating oxidative degradation of polyethylene. Conversely, Si_3N_4 ceramics exerted a protective role towards the polyethylene liner by scavenging oxygen from the tribolayer. The results of this work provide new insights into the interaction between bioceramics and polymers, which should also be considered when designing the next generation artificial hip joints with significantly elongated lifetimes.
    关键词: UHMWPE;Wear;ZTA;Silicon Nitride;Oxidation
  • [会议] 钛合金陶瓷/超高分子量聚乙烯/石墨烯复合涂层的制备及小牛血清润滑下的摩擦学分析
    钛及钛合金具有优良的力学性能、耐腐蚀性和生物相容性,是一种理想的生物医用植入材料.然而,钛合金的耐磨损性能差,严重限制了其在各行业的广泛应用.到目前为止,为了提高其耐磨性,研究人员对Ti6Al4V合金的表面改性进行了大量的研究,包括离子注入,热氧化,物理气相沉积(PVD)、激光熔覆、激光表面织构化(LST)等.本文中,等离子电解氧化(PEO)和浸渍提拉这两种方法先后作用于Ti6Al4V合金表面,对其进行表面改性.少量的石墨烯(GR)被添加到超高分子量聚乙烯(UHMWPE)中,用于浸渍提拉.改性后,复合涂层的摩擦磨损行为使用销盘式摩擦磨损试验机进行了研究.
    关键词: 复合涂层;钛合金陶瓷;超高分子量聚乙烯;石墨烯;制备工艺;摩擦性能
  • [会议] Study on Ultra High Molecular Weight Polyethylene Fibersdyed with High Hydrophobic Dyes
    In order to dyeultrahigh molecular weight polyethylene (UHMWPE) fibers, the dyeing properties of methyl yellow dye with high planarity and super hydrophobic structure on extracted UHMWPE fiber were studied. The effects of dyeing parameters such as temperature, time, dispersant concentration and pH value of the dyeing bath were evaluated through the K/S value and dyeing fastness. The cry stallinity, orientation degree and fiber strength were examined to study the hot drawing process of extracted UHMWPE fiber dyed via acheese dyeing machine. The results showed that the methyl yellow dye had better dye ability for extracted UHMWPE fiber. The optimal dyeing process was achieved at a concentration of dispersant 0.3%, 100℃ for 30min with pH value 7 to 8. The K/S value reached 20.3, the color fastness to rubbing and washing was above3 ratings, and reduction rate of the breaking strength of the dyed fiber was 4.34 %. After hot drawing 2.3 times by third-level drafting, the melting point and crystallinity of the dyed UHMWPE fibers after extraction were close to the finished UHMWPE fibers, and the orientation degree was higher than the finished fibers. The process of dyeing fiber after extraction and drawing the dyed fiber can avoid high strength loss caused by high temperature and the high pressure dyeing method.
    关键词: Ultra High Molecular Polyethylene Fiber;Super Hydrophobicity;Dyeability;Hot Drawing;Extraction
  • [会议] Study on Preparation of Ultrahigh Molecular Weight Polyethylene Fibers
    Ultra High Molecular Weight Polyethylene (UHMWPE) fibers are widely used in all walks of life because of their excellent properties and have attracted the attention of many experts and scholars at home and abroad. Research and preparation of domestic UHMWPE fiber has been for decades, although great progress has been made, but overall, the domestic UHMWPE fiber production is small, low quality and stability needs to be further improved. Therefore, it is very important to study the preparation of UHMWPE fiber and the mechanism of its microstructure evolution.
    关键词: Ultrahigh Molecular;Weight Polyethylene Fibers;Preparation
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