共查询到19条相似文献,搜索用时 218 毫秒
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由乙烯高效催化聚合而得的超高分子量聚乙烯的研究 总被引:1,自引:1,他引:0
本工作系研究以高效催化聚合获得的超高分子量聚乙烯的结构和性能。用扫描电子显微镜观察了高效催化剂及初生聚乙烯的形态。透射电子显微镜观察了初生聚乙烯粉未,发现毛遂边缘的超分子原纤维状织态结构。用偏光显微镜观察了不同分子量聚乙烯粉末的熔融和冷却结晶过程,生成的球晶随分子量增大而增大。用X-射线衍射、差热分析、倒换气相色谱测定了初生聚乙烯的结晶度随分子量而增大;用X-射线衍射、差热分析及密度梯度法测定经退火或热压制的聚乙烯样品的结晶度均随分子量增大而下降。X-射线衍射测定其晶粒尺寸亦随分子量增大而减小。差热分析和倒换气相色谱测定超高分子量聚乙烯粉末的结晶熔点温度(Tm)要比普通分子量聚乙烯高8-12℃。不同分子量聚乙烯的热形变曲线表明,超高分子量聚乙烯在熔融温度后出现明显的橡胶态。此外,还用差热与热重分析研究了超高分子量聚乙烯的热老化行为。测定了超高分子量聚乙烯的优异抗冲强度和沙浆磨耗量。并用扫描电镜对比观察了常规分子量和超高分子量聚乙烯试样的冲击断面的织态结构。 相似文献
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超延伸高分子量聚乙烯力学性能的研究王维泮,张凤英(北京化工大学高分子系北京100029)关键词超高分子量聚乙烯,冷拉伸,超延伸,延伸比随着高科技的发展,对材料性能的要求越来越高.目前一些发达国家正在致力于高机能、超强力的塑料.使高分子高度取向是获得高... 相似文献
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介绍了“十五”期间国内合成树脂、合成纤维、合成橡胶等高分子材料生产技术的新进展.聚合工艺技术开发方面,大型化的聚丙烯、聚乙烯、聚酯、顺丁橡胶、SBS热塑性弹性体、溶聚丁苯橡胶、丁基橡胶等高分子聚合成套工艺技术相继开发成功,建成了国产化的生产装置.纺丝成套工艺技术开发方面,大容量涤纶短纤、腈纶生产技术亦取得重要进展.合成材料新产品开发方面,合成树脂专用料比例、合成纤维差别化率和合成橡胶新产品比例均有了明显提高.化工新材料方面,在非通用合成树脂,如增粘PET、环氧树脂、聚氨脂,工程塑料,如尼龙6、PBT,以及高性能纤维,如超高分子量聚乙烯纤维、PBO纤维的合成工艺技术开发与新产品开发方面均取得了重要的进展. 相似文献
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A. S. Zabolotnov P. N. Brevnov V. V. Akul’shin L. A. Novokshonova F. A. Doronin A. G. Evdokimov V. G. Nazarov 《Polymer Science Series D》2018,11(3):297-302
The tribological properties and wear resistance under different action of composite materials based on of ultra-high-molecular-weight polyethylene (UHMWPE) and fillers of various types such as organomodified montmorillonite (MMT), graphite nanoplates (GNP), molybdenum disulfide, and shungite prepared via polymerization in situ are studied. According to the obtained results, the introduction of these fillers to UHMWPE in the amount of 0.4–7 wt % has almost no effect on the value of the coefficient of sliding friction on steel in the mode of dry friction. Composites with GNP, MoS2, and shungite are characterized by a significant (two- to threefold) increase in the wear resistance in the case of sliding friction on steel. The abrasive wear of composites in the case of friction on an abrasive paper is substantially affected by the type of filler, the use of MMT was the most effective for increasing the wear resistance of composites. In the case of a highspeed impact effect of water–sand suspensions all the studied composites are characterized by increased wear resistance in comparison with industrial UHMWPE at a low concentration of fillers and by an increase in the wear with the increase of the filler content. 相似文献
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Influence of chemical crosslinking on the creep behavior of ultra-high molecular weight polyethylene fibers 总被引:2,自引:0,他引:2
In this study, the effect of chemical crosslinking on the creep behavior of high-strength fibers, obtained by gel-spinning and subsequent hot-drawing of ultra-high molecular weight polyethylene (UHMWPE), is examined. In the first part of the paper, the general aspects of the creep behavior of these fibers are discussed. The second part deals with UHMWPE fibers that are crosslinked by means of a) chlorosulfonation and b) dicumyl peroxide treatment followed by UV irradiation. The latter technique leads to an improvement of the creep resistance of the UHMWPE fibers without affecting their high tensile strengths. In spite of the fact that the network formation is fairly high, the creep cannot be completely removed. The results indicate that the creep process in UHMWPE fibers is associated with a deformation mechanism in the crystalline regions of the fiber, which are not affected by chemical crosslinking. 相似文献
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Modification effects of short carbon fibers on mechanical properties and fretting wear behavior of UHMWPE composites
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Qiufeng Wang Hongling Wang Yunxia Wang Fengyuan Yan 《Surface and interface analysis : SIA》2016,48(3):139-145
The present work comparatively studied the modification effects of short carbon fiber (CF) on the mechanical properties and fretting wear behavior of ultra‐high molecular weight polyethylene (UHMWPE)/CF composites. The interactions between CFs and UHMWPE interface were also investigated in detail. The results showed that, with the increase in fiber content, the compressive modulus and hardness of the composites increased, while its impact strength decreased. It was found that filling of CF can reduce the friction and wear of UHMWPE. In addition, the UHMWPE‐based composites reinforced with nitric acid‐treated CF exhibited better mechanical properties, lower friction coefficient, and higher wear resistance than those of untreated UHMWPE/CF composites. This was attributed to the improvement of interfacial adhesion and compatibility between CF and UHMWPE matrix caused by surface chemical modification of CF. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Ultra-high molecular weight polyethylene (UHMWPE) is a high performance material that has excellent wear and impact strength compared to other polymers. Due to its chemical structure and molecular mass, UHMWPE is difficult to handle on standard extrusion systems. In this paper, the compounding, rheological, and mechanical behavior of different Polypropylene (PP)/UHMWPE blends were investigated. Raw materials were blended on a co-rotating twin screw extruder. The shear and extensional viscosity of polymer blends were investigated using an inline rheometer. Mechanical and rheological properties were presented for various UHMWPE loadings, and correlations between mechanical and rheological data were examined. 相似文献
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Xueqin Kang Chi Yao Chunmin Yang Peizhong Feng 《International Journal of Polymer Analysis and Characterization》2017,22(5):383-393
The change in oxidative degradation and mechanical properties of ultrahigh molecular weight polyethylene (UHMWPE) samples was evaluated. The percentage of crystallinity, chemical composition, and wetting properties were performed on different UHMWPE samples. Experimental results showed that the percentage of crystallinity and O/C ratio increased after immersion in simulated body fluids (SBF) for 5 years, and this resulted in lower mechanical properties. A coarse surface quality of UHMWPE surface caused lower contact angle and higher initial friction coefficient after the coeffect of force and SBF, but other mechanical properties changed little. The wear mechanism changed when immersed in SBF for 5 years. 相似文献
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利用新的单中心Ziegler-Natta(Z-N)催化剂,通过干预分子链的生长与聚集行为,可获得低缠结的超高分子量聚乙烯(UHMWPE)初生树脂.本研究利用这类低缠结UHMWPE,通过设置不同的烧结温度(Ts)来改变熔体缠结状态,并探讨了链缠结程度对烧结制品结构与性能的影响.实验结果表明TS=220℃下,UHMWPE样品发生显著的复缠,造成高缠结度;而Ts=170℃下,初始低缠结状态能够得以充分保留,从而获得了缠结度具有明显差别的不同样品.示差扫描量热法(DSC)测试表明,在Ts=170℃下,低缠结度有利于在随后等温及冷却结晶过程中生成高熔点(最高达141℃)晶体与高的结晶度(最高达65%).力学测试表明低缠结度制品的综合力学性能显著提升,其中屈服强度提高72%,拉伸断裂强度提升139%,弹性模量提升162%以及断裂伸长率提升36%,实现了同时增强增韧.这就提供了一种从调节链缠结温度实现UHMWPE烧结制品高性能化的新思路. 相似文献
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Zhen Zheng Xiaozhen Tang Meiwu Shi Guotai Zhou 《Journal of Polymer Science.Polymer Physics》2004,42(3):463-472
To prevent the loss of fiber strength, ultrahigh‐molecular‐weight polyethylene (UHMWPE) fibers were treated with an ultraviolet radiation technique combined with a corona‐discharge treatment. The physical and chemical changes in the fiber surface were examined with scanning electron microscopy and Fourier transform infrared/attenuated total reflectance. The gel contents of the fibers were measured by a standard device. The mechanical properties of the treated fibers and the interfacial adhesion properties of UHMWPE‐fiber‐reinforced vinyl ester resin composites were investigated with tensile testing. After 20 min or so of ultraviolet radiation based on 6‐kW corona treatment, the T‐peel strength of the treated UHMWPE‐fiber composite was one to two times greater than that of the as‐received UHMWPE‐fiber composite, whereas the tensile strength of the treated UHMWPE fibers was still up to 3.5 GPa. The integrated mechanical properties of the treated UHMWPE fibers were also optimum. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 463–472, 2004 相似文献
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Chemical modification on UHMWPE microparticles to improve the interfacial and tribological properties of UHMWPE/carbon fabric/phenolic laminate in water environment
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Ning Liu Jianzhang Wang Jie Yang Gaofeng Han Fengyuan Yan 《Surface and interface analysis : SIA》2016,48(1):40-46
Carbon fabric (CF)/phenolic laminates filled with pristine and chromic acid treated ultra high molecular weight polyethylene (UHMWPE) microparticles were fabricated. Their interfacial and tribological properties in water environment were comparatively investigated. The interlaminar shear strength (ILSS) of the laminates was tested on a universal testing machine (DY35), and the tribological properties were evaluated by a block‐on‐ring tribo‐tester. The worn surfaces and the interfaces of the laminates were respectively analyzed by scanning electron microscope (SEM) and field emission SEM (FESEM). The change of the chemical composition of UHMWPE microparticles after chromic acid etching was analyzed by Fourier transform infrared spectroscopy (FTIR). The chemical state of carbon fiber surface was examined using X‐ray photoelectron spectroscopy (XPS). The results revealed that the chromic acid treated UHMWPE microparticles had more remarkable effect than the pristine ones on improving not only ILSS and wear resistance of CF/phenolic laminate, but also its immunity to water environment. This should be attributed to the strengthened interfaces in treated UHMWPE/CF/phenolic laminate, which were characterized by the drawn dendritic UHMWPE fibrils firmly clinging on the surfaces of carbon fibers and resin in a Boston ivy‐like manner. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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In the present study, an accelerated ageing by oxidative degradation of UHMWPE in hydrogen peroxide solution was performed and the inhibition with ascorbic acid (vitamin C) was analyzed. Both systems were extensively characterized by Fourier Transformed Infrared Spectroscopy (FTIR). Different chemical groups of UHMWPE associated with the degradation reaction were monitored for over 120 days in order to evaluate the possible oxidation mechanisms involved and the inhibitory behavior of vitamin C. The results have provided strong evidence that the oxidation mechanism is rather complex, and 2 stages with their own particular first-order kinetics reaction patterns have been clearly identified. Furthermore, the vitamin C has proven to be an efficient antioxidant for UHMWPE under the evaluated conditions. 相似文献