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Changwoon Nah Jee Young Lim Rajatendu Sengupta Baik Hwan Cho Alan N Gent 《Polymer International》2011,60(1):42-44
The interactions of carbon nanotubes (CNTs) and carbon black (CB) with rubber matrices are of great interest. Although both belong to the carbon filler family, their interactions are different. In this study the adhesion of CNTs, if any, with natural rubber (NR) was examined. Scanning electron microscopy examinations made on cryogenically fractured surfaces of a crosslinked NR sample containing 7% by weight of CNTs showed that the CNT bundles emerged from the side surface (narrowed by Poisson's ratio) and slowly slid back in when the deformation was removed. The protruded lengths were many times larger than the nanotube bundle diameters. This extensive slipping out of CNTs from the rubber matrix suggests that interfacial interactions between CNTs and NR are quite weak. In contrast, relatively strong interactions were found between CB and rubber, indicated by the large amount of bound rubber formation. Reinforcement of rubber by CNTs is therefore attributed to the large aspect ratio of CNT bundles. Physical entanglement with rubber molecules is then able to generate effective load transfer, replacing the strong adhesion found with CB. Copyright © 2010 Society of Chemical Industry 相似文献
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采用体积分数分别为15%、30%和45%的橡胶粉或橡胶块颗粒对混凝土中粗骨料进行替换,并用自由振动法对橡胶混凝土简支梁的振动频率和阻尼性能进行测试,考察了小变形时阻尼比与橡胶颗粒大小和数量之间的关系。采用弹性波法和梁单元法对橡胶混凝土的动力模量进行了测量,并对其静弹性模量与动弹性模量进行了对比。结果表明,橡胶混凝土的动力弹性模量低于普通混凝土。橡胶块对橡胶混凝土动、静弹性模量的影响均大于橡胶粉。普通混凝土的动弹性模量比静弹性模量高37.4%,而橡胶混凝土的动弹性模量比静弹性模量高约50%。橡胶混凝土的阻尼比随最大响应幅值的增大而增大。相比于普通混凝土,橡胶混凝土的阻尼对振动的响应更为敏感。橡胶混凝土的阻尼比随橡胶含量的增加而显著增大。当橡胶的体积分数为30%时,橡胶混凝土综合性能较佳。 相似文献
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Scrap rubber recycling combined with waste leather particles in natural rubber compounds has been studied. The effect of leather and scrap rubber loading on vulcanization characteristics of natural rubber compounds has been evaluated. The presence of leather was found to reduce the scorch time and increase the maximum and minimum torque. While reversion was not observed in the absence of leather at 150 °C, it was more prominent when leather was incorporated. Mechanical properties such as tensile strength, elongation at break, tear strength, modulus and hardness were found to increase on increasing the scrap rubber loading in the absence of leather. Compounds containing leather exhibited higher tensile strength, modulus, hardness and tear strength values but the modulus and hardness values were found to decrease as the scrap rubber loading increased. All the vulcanizates exhibited only limited swelling in different media as the swelling of one phase of the composite was found to be restricted by the other phase. Copyright © 2004 Society of Chemical Industry 相似文献
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设计3种不同再生骨料取代率的再生混凝土立方体试件,分别在7 d、14 d、28 d、100 d龄期进行抗压强度试验,结果表明:长龄期再生混凝土立方体抗压强度有所增大,但高取代率比低取代率的抗压强度降低,再生混凝土后期强度增长速率高于普通混凝土。对试验室实测的再生混凝土立方体抗压强度与试验龄期进行拟合,拟合结果相关系数均大于0.97,吻合结果较好。 相似文献
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再生混凝土被视为节约材料的一种重要举措,同时,废旧轮胎橡胶粉的适量掺入可以优化混凝土的性能.为使两种废弃材料合理利用,本文以废旧轮胎橡胶粉和废弃混凝土加工生成的再生骨料为研究对象,研究了外掺废旧轮胎橡胶粉对再生混凝土力学特性的影响.通过对再生混凝土基准组的试验研究,得到了再生混凝土前28 d的强度发育规律,结合此规律并在其他学者研究的基础上拟合出再生混凝土早期抗压强度数学模型;同时,对再生混凝土外掺不同粒径(20目、60目、80目、100目、120目)和不同掺量(3%、6%、9%)的橡胶粉,并研究此情况下橡胶粉对不同龄期再生混凝土的抗压强度的影响.试验结果表明:掺入橡胶粉会降低再生混凝土的抗压强度;当掺入粒径为20目,掺量为3%的橡胶粉时,再生混凝土抗压强度最好. 相似文献
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天然橡胶发泡材料的压缩行为与能量吸收特性 总被引:1,自引:0,他引:1
用发泡剂N,N′-二亚硝基五次甲基四胺(简称发泡剂H)制备了天然橡胶(NR)发泡材料,研究了不同密度的NR发泡材料的压缩行为和能量吸收特性。结果表明,随着发泡剂H用量的增加,NR发泡材料的密度与硬度均降低;NR发泡材料的压缩应力-应变曲线有2个阶段:线性弹性阶段和致密化阶段;随着发泡材料密度的减小,线性弹性区变宽,相对弹性模量降低。在应力较小的时候,密度小的NR发泡材料吸收能量较多,在应力较高的时候,密度大的NR发泡材料吸收能量多。随着发泡材料密度的减小,其吸能效率最大值与理想参数最大值提高。 相似文献
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The variation of the green strength of natural rubber (NR) with the preparation method of the film was studied to elucidate the origin of the stress–strain behavior characteristics of NR in connection with the structure of branch points in NR. A rubber film prepared via casting from NR latex showed the highest modulus and green strength in comparison with films prepared via casting from a toluene solution and via the hot pressing of dry rubber. The modulus and green strength of the NR latex‐casting film decreased after the hot‐press treatment of the film. On the other hand, no difference was observed for synthetic cis‐1,4‐polyisoprene rubber with the preparation method of the film or the heat treatment. This stress–strain behavior characteristics of NR can be ascribed to the changes in the branch points of the NR film with the casting method, which may result in differences in entanglement and crystallizability on stretching. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
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According to the analysis of the domestic and overseas researches and achievements of lightweight aggregate concrete, a new strength formula on account of tube compressive strength of lightweight aggregate and glue-capacity ratio is put forward on the mix ratio design of lightweight aggregate concrete. The conception of concrete filler coefficient is also proposed, the theoretical formula of sand-aggregate ratio is deduced and the quasi-principle of stationary water consumption by considering the working character of concrete is summarized. Therefore, the designing equation of mix ratio of lightweight aggregate concrete which is tested by some further experiments is defined. 相似文献
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以不同比例的粉煤灰、矿粉、天然矿物和活化剂,进行双掺、三掺和四掺配制成复合胶凝材料,并按不同比例等量替代水泥配制C30混凝土(水胶比为0.49),然后测定各试样混凝土拌合物的坍落度以及7d,28d,60d的混凝土抗压强度。结果表明:(1)以粉煤灰、矿粉、天然矿物和活化剂四掺配的复合胶凝材料35%~40%等量替代水泥,其拌合物的坍落度比基准混凝土提高15%-33%,其混凝土的60d龄期抗压强度可比基准混凝土提高9%-14%以上;(2)试验条件下最佳的复合胶凝材料配料方案为:粉煤灰30%-50%、矿渣30%-60%、天然矿物5%-10%、活化剂为5%-10%。 相似文献
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A solid-state chemical reaction occurs when a solvent cast film of a blend of masticated natural rubber and chlorinated natural rubber is heated in the presence of air at 150°C. The thermal behavior of solvent cast films of chlorinated natural rubber, masticated natural rubber, and a 1 : 1 w/w blend (2% w/v in xylene) of these two polymers has been studied using differential scanning calorimetry, infrared spectroscopy, scanning electron microscopy, and nuclear magnetic spectroscopy. The results suggest that carbonyl groups are incorporated into the blend on heating and that the vinyl functionality of the isoprene units is modified during this apparent oxidation. Heating for 2 h at 150°C results in a material that no longer contains the rubber-like cis-1,4-polyisoprene units. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1379–1384, 1997 相似文献
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ABSTRACTIn this work, polymer-bonded sugars were used as a substitutive material for polymer-bonded explosives (PBXs). Their production process and damage mechanism under compressive process were analysed. We also investigated the initial Poisson’s ratio of PBXs as well as their mechanical properties under quasi-static compression and variation of Poisson’s ratio during the one-dimensional compressive process. Compressive expansion behaviour due to compressive loading was investigated comprehensively. It was found that due to the damage caused by the loading process, volumetric strain and Poisson’s ratio showed three stages characteristic. Experimental results proved that compression–expansion had occurred during the one-dimensional compressive process. Simulation results verified that PBXs crystal underwent mainly transgranular fracture under quasi-static compression. 相似文献
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This study investigates the fire reaction properties of concrete made with recycled rubber aggregate (CRRA). Four different concrete compositions were prepared: a reference concrete (RC) made with natural coarse aggregate and three concrete mixes with replacement rates of 5, 10 and 15% of natural fine and coarse aggregate by recycled rubber aggregate (RRA) obtained from used tyres. Specimens of CRRA were tested in a cone calorimeter according to the test standard ASTM E1354, submitted to heat fluxes of 25, 50 and 75kW/m2. These tests evaluated the effects of incorporating RRA in the fire reaction properties of concrete, namely in the heat release rate, the time to ignition (TTI), the remaining mass, the production of smoke, and the release of carbon dioxide and carbon monoxide. Owing to the organic nature of RRA, with the exception of the carbon monoxide yield, higher replacement rates of natural aggregates by RRA and increasing heat flux led to a worse fire reaction response, particularly in terms of TTI, heat release rate and smoke production. Results of these experiments were then used to estimate the European fire reaction classes of each concrete composition, using a flame spread model. All CRRA compositions tested were provisionally rated as class A2 or B and such ratings allowed defining the field of application of each solution under analysis, according to building code requirements. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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为了解掺加粉煤灰的砂浆和混凝土抗压强度相关性,成型了不同粉煤灰掺量的砂浆和混凝土试样。在砂浆和混凝土试样标准养护到一定龄期后,基于《建筑砂浆基本性能试验方法标准》JGJ/T70—2009和《普通混凝土力学性能试验方法标准》GB/T50081—2002中方法进行抗压强度试验,发现:在标养不超过360 d、粉煤灰掺量0~40%范围内,粉煤灰掺量和龄期分别对砂浆和混凝土抗压强度的影响趋势基本一致,可以用成型砂浆试件代替混凝土试件,来找寻一定配比混凝土最大抗压强度所对应的粉煤灰掺量。 相似文献