共查询到19条相似文献,搜索用时 140 毫秒
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EPDM闭孔发泡材料压缩应力松弛行为分析 总被引:3,自引:1,他引:3
闭孔发泡材料的应力松弛过程包含分子链段的应力松弛和因气体扩散而导致气体压力下降所引起的松弛两方面内容。本文根据菲克扩散定律,利用分离变量法和边界条件推出气体扩散对应力松弛的影响,在此基础上,结合未发泡材料应力松弛的研究成果,建立了闭孔发泡材料的应力松弛模型,采用该模型拟进一步研究EPDM橡胶发泡材料的应力松弛行为。 相似文献
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采用叠层法制备了发泡密度沿厚度方向呈梯度变化的三元乙丙橡胶(EPDM)发泡材料,研究了梯度结构对EPDM发泡材料的泡孔微观形态、力学性能、压缩应力-应变性能、能量吸收特性及动态力学性能的影响。结果表明,在叠层厚度不变的情况下,随着中间层发泡剂用量的减少,试样的邵尔C硬度、拉伸强度和扯断伸长率逐渐增大,100%和300%定伸应力在最内层发泡剂用量达到7份(质量)后不再增加,转而呈下降趋势。在较高的应力下,梯度EPDM发泡材料比传统均质橡胶发泡材料具有更强的吸能效果,而玻璃化转变温度和阻尼因子基本不变。 相似文献
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研究氯化聚乙烯橡胶(CM)/废旧三元乙丙橡胶(EPDM)胶粉共混发泡材料的性能,并采用活化剂420等对废旧EPDM胶粉进行活化改性,考察废旧EPDM胶粉改性对共混发泡材料的影响。结果表明:随着废旧EPDM胶粉用量的增大,共混发泡材料的门尼粘度增大,邵尔C型硬度减小,发泡倍率先增大后减小,发泡收缩率减小;废旧EPDM胶粉改性后,共混发泡材料的门尼粘度变化不大,M_H-M_L值增大,发泡倍率略有减小,但物理性能和发泡收缩率改善,且泡孔结构更密实、更完整。 相似文献
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Microcellular ethylene-propylene-diene monomer (EPDM) foams derived from miniaturizing the cellular structure can improve mechanical properties of traditional EPDM foams. It is a current challenge that microcellular EPDM foams prepared by supercritical CO2 foaming technology cannot undergo the post-crosslinking process due to the disappearance of cellular structure, which strongly restricts the development of the mechanical properties of EPDM foams. Hence, a scalable and blending route by selecting the silicone rubber (SR) with different crosslinking temperature compared to EPDM is developed to improve mechanical properties of EPDM foams. During the pre-crosslinking process of EPDM, SR forms a complete crosslinking network, which can make up for the strength of EPDM without the post-crosslinking. Meanwhile, the silica can reduce the domain size of SR and enhance the compatibility between EPDM and SR. As expected, the addition of SR improves the storage modulus, viscosity and matrix strength of EPDM, which shows enhanced mechanical properties of EPDM foams. When the foam density is basically the same, the tensile strength and compressive strength of SR/EPDM foam are increased by 461% and 283% respectively compared with that of EPDM foam. Finally, the maximum tensile strength and compressive strength (40% strain) of SR/EPDM foam achieves 3.58 MPa and 0.59 MPa, respectively. 相似文献
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In this paper, aramid fiber (AF)/ethylene-propylene-diene monomer (EPDM) microcellular foams added with different content of AF are prepared by the supercritical foaming method. The effect of the AF content on the rheological behavior, mechanical properties, thermal properties and cellular structure of the AF/EPDM microcellular foams has been systematically studied. The research illustrates that compared with pure EPDM, the AF/EPDM matrix has greater viscosity and modulus, which is conducive to reduce the cell size and increase its density. And the thermal stability of EPDM foams is improved with the addition of aramid fiber. Meanwhile, when the content of AF is added to 1 wt%, the AF/EPDM microcellular foam exhibits a relatively low thermal diffusion coefficient and apparent density with the thermal conductivity to 0.06 W/mK. When the AF is added to 5 wt%, the tensile strength of the AF/EPDM microcellular foam increases to 1.95 MPa, which is improved by 47% compared with that of the pure EPDM foam. Furthermore, when the compressive strain reaches to 50%, the compressive strength of the AF/EPDM microcellular foam is 0.48 MPa, improved by 296% compared with that of the pure EPDM foam. 相似文献
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研究了硅橡胶/三元乙丙橡胶(Q/EPDM)配方对泡沫合金的结构、密度、硬度、压缩、拉伸、应力松驰等力学性能的影响规律。研究表明:EPDM含量增加,泡沫合金的硬度、压缩强度、拉伸强度性能提高,而压缩永久变形、应力松驰性能下降。 相似文献
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进行了EVA/EPDM/IR三元共混和EVA/EPDM/IR/IR四元共混发泡材料的研制,经物性对比表明:共混发泡材料的物性较非共混发泡普遍提高。EPDM的混入可以增加发泡材料的拉伸强度和撕裂强度,同时降低收缩率和永久压缩变形;IR的混入除具备EPDM的优点外尚对提高发泡材料的柔软度有帮助;IR的混入仅改善发泡材料二次热压成型制品表面的清晰度。 相似文献
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In this research, sponge ethylene propylene diene rubber (EPDM) nanocomposites based on functionalized multi-walled carbon nanotubes (f-MWCNTs) and foaming agent azodicarbonamide (AZD) were successfully fabricated as potential acoustic-absorbing foams. Two crosslinking systems were utilized for stabilizing the foam structure and improving its properties by subsequent sulfur and electron beam irradiation at 50 kGy as a fixed dose. The impacts of the concentration of AZD, f-MWCNTs and crosslinking systems on acoustic and physico-mechanical properties were investigated. The results manifested that the optimum foaming content was 3 phr. The acoustic data exhibited satisfactory enhancement in the sound absorption coefficient (α) for irradiated foam nanocomposites compared to unirradiated nanocomposites. This was attributed to the barrier effect of f-MWCNTs in reducing the pore size of the foam, leading to an increase in the tortuous path in the foam matrix that stifled the sound waves from transferring into the bulk. Likewise, the compression properties were also improved. However, tensile stress and strain at break values for irradiated foams relatively decreased. The data obtained revealed an excellent possibility of using these EPDM foam nanocomposites for potential applications such as acoustic panels and airborne sound insulation. © 2022 Society of Industrial Chemistry. 相似文献
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用甲基丙烯酸(MAA)原位改性纳米碳酸钙填充三元乙丙橡胶(EPDM),制备了纳米碳酸钙增强EPDM硫化胶。考察了MAA对纳米碳酸钙增强EPDM硫化胶的应力软化效应及应力弛豫行为,并与未改性纳米碳酸钙、炭黑及白炭黑增强EPDM硫化胶的应力软化效应和应力弛豫行为进行了比较;用并联的Maxwell模型对应力弛豫行为进行了数学模拟。结果表明,MAA加剧了纳米碳酸钙增强EPDM的应力软化效应和应力弛豫行为。与其他3种填料相比,MAA原位改性纳米碳酸钙增强EPDM的应力软化效应更为显著,且其应力在室温停放后不能像其他填料增强EPDM那样得到明显恢复;MAA原位改性纳米碳酸钙增强EPDM的应力弛豫速率更快,应力弛豫程度也更大;并联Maxwell模型可以模拟未改性纳米碳酸钙、MAA原位改性纳米碳酸钙、炭黑及白炭黑增强EPDM的应力弛豫行为。 相似文献
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ABSTRACTIn this study, the effect of various nano-particle type and concentration on the structure, curing, viscosity variation during vulcanisation, and mechanical characteristics of ethylene–propylene–diene monomer (EPDM) rubber foam is reported. Three types of nanoparticle with various dimensional aspects (1D carbon nanotubes, 2D nano clay, and 3D nano silica) are employed to investigate their effect on the fabrication of EPDM rubber foam. It is observed that the properties of the foams were efficiently influenced by the nano-particle shapes and content in the matrix. Nanoparticles may increase cell density and change cell structures. In addition, they can change the curing behaviour of foam rubber by affecting curing rate and scorch time of rubber. In the end, mechanical properties of EPDM foam rubbers investigated by experimental tests and implementing few empirical and constitutional mechanical models. It is very helpful to use suitable nanoparticle to achieve desired properties out of fabricated foams. 相似文献
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The effect of curing system on the properties of the thermoplastic elastomer foams of ethylene‐vinyl acetate copolymer and styrene‐butadiene and ethylene‐propylene‐diene monomer rubbers 下载免费PDF全文
Thermoplastic elastomer (TPE) foams have important application in electrical, toys, and other industries. Several foams were prepared by ethylene‐vinyl acetate copolymer (EVA) lonely, and in combination with styrene‐butadiene and ethylene‐propylene‐diene monomer rubbers (SBR and EPDM). The effects of crosslinking and foaming agents and EVA type on density and mechanical properties of the cured foams with two curing systems, peroxide and sulfur‐peroxide with potential use in automotive applications, were studied. The results showed that proposed compounds formulations were foamed properly. The viscosity of the EVA was a key factor for the density values of the formed foams. The densities of the cured foams with peroxide system with various SBR contents were higher when compared with cured foams with sulfur‐peroxide system. With increasing foaming agent, the densities of the foams were reduced for studied curing systems. The densities of the EVA–EPDM foams were lower than those of the EVA–SBR foams in the same studied conditions. Increasing rubber in foam formulation had adverse effect on tensile properties of the foams. The existence of the talc powder in foam formulation had important role on the shape and type of the formed cells and resulted in foams with mostly closed cells. The results of this study help the automotive article designer to produce suitable TPE foam. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45357. 相似文献
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The relaxation behavior of the load in compression and the stress in tension was monitored at constant temperature and/or relatively humidity for a set of four slabstock foams with varying hard-segment content as well as two of the compression molded plaques of these foams. The majority of the compression relaxation tests were done at a 65% strain level in order to be consistent with the common ILD test. The tensile stress relaxation tests were performed at a 25% strain level. Over the 3-h testing period, a linear relationship between the log of compressive load or the log of tensile stress versus log time is observed for most testing conditions. For linear behavior, the values of the slope or the load/stress decay rate are comparable in both the tension and compression modes with the values being slightly higher in magnitude for the compression mode. These rates of decay are in the range of ?2.2 × 10 ?2 to ?1.7 × 10 ?2 for a 21 wt % hard-segment foam and ?3.2 × 10?2 to ?2.4 × 10?2 for a 34 wt % hard-segment foam. Increasing %RH at a given temperature does bring about a steady decrease in the initial load or initial stress as well as a slight increase in the rate of relaxation. The effect of temperature on the relaxation behavior is most significant at temperatures near 125°C and above. The FTIR thermal analysis of the plaques indicates that this significant increase is due to additional hydrogen bond disruption and possible chain scission taking place in the urea and urethane linkages that are principally present in the hard segment regions. The relaxation behavior in both tension and compression is believed to be mostly independent of the cellular texture of the foam at the strain levels given above. This conclusion is based on the similar relaxation behavior between the plaques and the foams. © 1994 John Wiley & Sons, Inc. 相似文献