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.
Alfredo Rondinella;Elia Marin;Bryan J. McEntire
会议集名/来源：Bioceramics 30: Selected, peer reviewed papers from the 30th Symposium and Annual Meeting of the International Society for Ceramics in Medicine(ISCM), October 26-29, 2018, Nagoya, Japan
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.
Xiao-Chun Wang;Jin-Long Yan;Jian-Fei Zhang;Li-Ping Zhang;Guo-Liang Zhao;He Sun;Xiao-Xiao Wang
会议集名/来源：11th Textile Bioengineering and Informatics Symposium Proceedings (TBIS 2018), Vol.2: Manchester(GB).25-28 July 2018
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.
Ultra High Molecular Polyethylene Fiber;Super Hydrophobicity;Dyeability;Hot Drawing;Extraction
会议集名/来源：3rd International Workshop on Materials Engineering and Computer Sciences: IWMECS 2018, Jinan, China, January 27-28, 2018
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.