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51.
Fracture toughness and fatigue crack propagation (FCP) of plain and modified anhydride-cured epoxy resin (EP) were studied at ambient temperature. Liquid carboxyl-terminated acrylonitrile-butadiene (CTBN) and silicon (SI) rubber dispersions were used as tougheners for the EP. The morphology of the modified EP was characterized by dynamic mechanical analysis (DMA) and by scanning electron microscopy (SEM). The fracture toughness, Kc, of the compositions decreased with increasing deformation rate. Kc of the EP was slightly improved by CTBN addition and practically unaffected by incorporation of the SI dispersion when tests were performed at low cross-head speed, v. Both modifiers improved Kc at high v, and also the resistance to FCP, by shifting the curves to higher stress intensity factor ranges, ΔK, by comparison with the plain EP. It was established that both fracture and fatigue performance rely on the compliance, JR, at the rubbery plateau, and thus on the apparent molecular mass between crosslinks, Mc. The failure mechanisms were less dependent upon the loading mode (fracture, fatigue), but differed basically for the various modifiers. Rubber-induced cavitation and shear yielding of the EP were dominant for CTBN, whereas crack bifurcation and branching controlled the cracking in SI-modified EP. The simultaneous use of both modifiers resulted in a synergistic effect for both the fracture toughness at high deformation rate and the FCP behavior. 相似文献
52.
53.
介绍了Y型橡胶模具的设计 ,重点对模具结构和模腔尺寸进行了分析和阐述 ,经生产验证 ,此模具结构合理 ,定位可靠 ,操作方便 ,从而为同类产品的设计提供了参考。 相似文献
54.
中国橡胶工业崛起之思考 总被引:5,自引:2,他引:3
中国已经成为橡胶工业大国,不少产品名列世界前茅,橡胶工业已是占全国GDP 1%的制造业。从2000—2004年橡胶消耗量、汽车轮胎生产量、非轮胎制品用胶量等方面的统计数据中可以看出我国橡胶工业已经崛起,分析了崛起的原因,对存在的问题进行了思考,提出了解决的方法。 相似文献
55.
黄浦江上游水源地突发性水污染事故应急处置预案探讨 总被引:5,自引:0,他引:5
阐述了水源地突发污染事件的概念、特点及其对于供水安全和城市经济社会系统安全运行的重要意义.论述了城市水源地突发污染事件应急研究的主要内容;以上海市黄浦江上游水源地为例,探讨了突发性污染事件应急处置体系的构建,并提出了相应的政策建议。 相似文献
56.
Nelly RahmanApriyanti Isanasari Ririn AnggraeniSuharto Honggokusumo Masatoshi Iguchi Toru MasukoKohji Tashiro 《Polymer》2003,44(1):283-288
To investigate the mechanism of high elongation of natural rubber attained by the ‘racking method’, a strip of smoked-sheet was elongated up to 150 times in length, by stretching rapidly at room temperature and forcing to shrink at 75-80 °C repeatedly. On X-ray diffraction, a typical fibre pattern with an amorphous ring appeared already at ×10 (stretch ratio=10). The degree of crystallinity increased to the level of 17-18% at ×20 and turned to decrease after ×60, but the degree of crystallite orientation reached at a high level already at ×10 and did not change significantly and the half-height width of reflection profiles stayed almost at a constant level, while the Young's modulus increased up to ca. 300 MPa at ×100 and then fell rather discontinuously. It was assumed that some fractions of chain segments between entanglements were gradually broken in each step of stretching operation, rather than disentangled and slipped. 相似文献
57.
A series of short fibre reinforced styrene butadiene rubber (SBR) composites were prepared by incorporating sisal fibres of
different lengths and different concentrations. The vulcanization behaviour and the properties of the vulcanizates were measured
by the relevant ASTM procedures. The processing characteristics such as green strength and mill shrinkage were improved by
the addition of fibres. The properties like tensile strength, tear strength, moduli at 10% and 20% elongations were found
to be maximum for composites containing longitudinally oriented fibres of length 6 mm. Mixes containing 35 phr loading of
fibres and bonding agent showed better mechanical performance than others. The failure behaviour of tensile and tear specimens
have been analysed by scanning electron microscopy techniques.
Paper presented at the poster session of MRSI AGM VI, Kharagpur, 1995 相似文献
58.
This paper is the first part of a work devoted to the setting-up of a methodology for the mechanical behaviour characterization of rubber-like materials, using a digital speckle extensometer. We present here the experimental approach, specific to large strain measurements. The proposed method is based on in-plane kinematics measurements using an optical extensometer. The whole two-dimensional field of in-plane displacements is obtained by a digital image processing. We discuss then the correlation calculations and how to achieve the optimal subset matching. Next, we specify how to derive the principal stretch ratios, and the accuracy on these components, issued from a subsequent numerical calibration.Finally, we present experimental data dealing with a carbon black, filled natural rubber, issued from uniaxial traction tests, pure shear tests, and tensile tests performed on double-edge notched tensile specimens. 相似文献
59.
硅橡胶机械强度改进方法的研究 总被引:3,自引:0,他引:3
使用以硅橡胶为绝缘材料的新一代高压复合绝缘子是解决输变电线路污闪问题行之有效的方法,针对复合绝缘子用硅橡胶生产和运行中存在的主要问题,从添加补强材料白炭黑(最佳用量在35份左右)和改变硫化时间(最佳硫化时间8min)两方面入手进行试验,研究如何改善硅橡胶的机械强度尤其是抗撕裂强度。 相似文献
60.
影响喷气燃料与橡胶相容性的因素 总被引:5,自引:0,他引:5
采用几种具有不同初始物理性能及不同丙烯腈含量、不同硫化剂和硫化程度的丁腈橡胶,考察了其配方和物理性能对采用不同工艺条件生产的喷气燃料的相容性。结果表明,喷气燃料与橡胶的相容性不仅与喷气燃料的加工工艺有关,而且与橡胶的组成及其制备工艺有关。采用非加氢工艺生产的喷气燃料与橡胶的相容性好于采用加氢工艺(特别是加氢裂化工艺)生产的喷气燃料。橡胶材料的初始力学性能的好坏并不完全决定其与喷气燃料相容性的好坏,橡胶材料的耐过氧化物侵蚀能力才是影响相容性好坏的主要因素。橡胶的组成和其制备工艺决定了橡胶在喷气燃料中萃取物的数量和组成,不同萃取物的综合作用给相容性带来不同程度的影响。用硫作硫化剂的橡胶虽然原始强度低于用过氧化物作硫化剂的橡胶,但前者与喷气燃料的相容性却远好于后者。 相似文献