不同填料填充丁苯橡胶复合材料裂纹尖端扩展行为研究

发布时间：2018-05-18 18:36

本文选题：丁苯橡胶 + 碳纳米管　；参考：《北京化工大学》2015年硕士论文

【摘要】：橡胶制品的裂纹尖端应变分布及其与准静态裂纹扩展、动态疲劳破坏性能的关系近年来受到了广泛的关注。本文的研究重点在于考察填料种类和用量对丁苯橡胶复合材料裂纹尖端应变分布的影响,进而评价材料的抗裂纹萌生和扩展性能。研究的填料体系包括纯炭黑体系、纯碳纳米管体系、碳纳米管等量替代炭黑体系以及碳纳米管非等量替代炭黑体系。首先考察了炭黑粒径的变化对其填充丁苯橡胶得到复合材料的抗裂纹性能的影响。采用数字图像相关法对材料裂纹尖端附近区域的应变分布情况进行测定。结果表明,裂纹最尖端一点应变放大程度最强,距离尖端越远应变放大效应越弱；同一材料裂纹尖端最大应变随整体应变呈线性增加；裂纹尖端应变放大效应的作用区域均随炭黑粒径增加而减小。综合填料网络结构和准静态裂纹萌生及扩展测试的结果,发现炭黑N234填充丁苯橡胶抗裂纹性能最好而炭黑N990最差的规律并进行了解释。同时采用有限元分析法对与炭黑填充丁苯橡胶有着同样单轴拉伸应力应变性质的试样表面进行了应变分布的模拟,由于Ogden方程在计算时忽略了材料实际的滞后特性,模拟结果在试样整体应变大于30%时与数字图像相关法实验结果存在较大偏差。然后研究了碳纳米管以1：1的比例部分替代炭黑N234填充丁苯橡胶准静态下的抗裂纹表现。采用1至3份碳纳米管分别替换相同份数的炭黑N234,结果表明,随着碳纳米管用量增加,过强的填料网络结构不利于分担裂纹尖端橡胶分子链承受的应力集中效应,反而强化了应变放大程度,不利于得到抗裂纹性能较好的复合材料。为了探讨碳纳米管作为填料部分替代炭黑的合理比例,对比研究了5份碳纳米管、20份及40份炭黑N234填充丁苯橡胶的填料网络结构和局部应变分布对其抗裂纹萌生及扩展性能的影响。虽然5份碳纳米管具有和40份炭黑N234相近的形成填料网络结构的能力,但受到碳纳米管与橡胶基体作用较弱的特性的影响,在力学性能和抗裂纹性能方面5份碳纳米管却接近20份炭黑填充后的丁苯橡胶。若使碳纳米管与炭黑共同形成的填料网络结构与纯炭黑接近,碳纳米管特殊的几何形貌对阻碍裂纹扩展的作用似乎会更明显,因此选用1份对应4份的比例,继续碳纳米管部分替代炭黑填充丁苯橡胶的实验。静态裂纹萌生及扩展实验和表面应变分布分析结果表明：3份碳纳米管替代12份炭黑N234加入丁苯橡胶后得到的材料具有较纯炭黑填充更低的裂纹尖端应变放大效应且更多的分子链参与均化应力集中的过程,宏观上表现出最好的抗裂纹性能。
[Abstract]:The strain distribution at the crack tip of rubber products and its relationship with quasi-static crack propagation and dynamic fatigue failure properties have attracted extensive attention in recent years. The emphasis of this paper is to investigate the effect of filler type and content on the strain distribution at crack tip of SBR composites, and to evaluate the crack initiation and propagation properties of the materials. The filler system includes pure carbon black system, pure carbon nanotube system, carbon nanotube substitution carbon black system and carbon nanotube alternative carbon black system. The effect of the particle size of carbon black on the crack resistance of the composites filled with SBR was investigated. The strain distribution near the crack tip of materials was measured by digital image correlation method. The results show that the maximum strain amplification at the tip of the crack is the strongest, and the strain amplification effect is weaker when the crack tip is farther away from the crack tip, and the maximum strain at the crack tip of the same material increases linearly with the overall strain. The effect of strain amplification at crack tip decreases with the increase of carbon black particle size. Based on the network structure of filler and the results of quasi static crack initiation and propagation test, it is found that carbon black N234 filled SBR has the best crack resistance and the carbon black N990 is the worst. At the same time, the finite element analysis method was used to simulate the strain distribution on the surface of the sample with the same uniaxial tensile stress-strain property as the carbon black filled styrene-butadiene rubber. The Ogden equation neglects the actual hysteresis of the material. When the total strain of the sample is greater than 30, there is a big deviation between the simulated results and the experimental results of digital image correlation method. The crack resistance of N234 filled butadiene rubber filled with carbon black N234 at 1:1 was studied. The carbon black N234 with the same number of carbon black was replaced by 1 to 3 phr carbon nanotubes respectively. The results show that with the increase of carbon nanotube content, too strong packing network structure is not conducive to sharing the stress concentration effect of the crack tip rubber molecular chain. On the contrary, the strain amplification degree is strengthened, which is not conducive to obtaining the composites with better crack resistance. In order to study the reasonable proportion of carbon black partially replaced by carbon nanotubes as filler, The effects of filler network structure and local strain distribution on crack initiation and propagation of 5 carbon nanotubes (CNTs) 20 and 40 carbon black N234 filled styrene-butadiene rubber (SBR) were studied. Although 5 carbon nanotubes have the ability to form filler network similar to 40 carbon black N234, they are affected by the weak interaction between carbon nanotubes and rubber matrix. In terms of mechanical properties and crack resistance, 5 phr carbon nanotubes were found to be close to 20 phr carbon black filled styrene-butadiene rubber. If the network structure of the filler formed by carbon nanotubes and carbon black is close to that of pure carbon black, the effect of the special geometry of carbon nanotubes on the crack growth appears to be more obvious. The experiment of partially replacing carbon black with styrene-butadiene rubber by carbon nanotubes was carried out. The static crack initiation and propagation experiment and surface strain distribution analysis showed that the strain amplification effect at crack tip was lower after adding 12 phr carbon black N234 instead of 12 phr carbon black N234. The results showed that the strain amplification effect at crack tip was lower than that filled with pure carbon black. And more molecular chains participate in the process of homogenizing stress concentration, Macroscopically, it shows the best crack resistance.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ333.1;TB33

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