EPDM闭孔发泡材料压缩应力松弛行为分析

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。     

梯度结构三元乙丙橡胶发泡材料的制备及性能

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。     

一种汽车用带橡胶支架的发泡片材

本实用新型涉及一种汽车用带橡胶支架的发泡片材,用于填充汽车D柱外腔、后围板留下的不规则空隙,实现密封和阻隔噪音的传递。包括自粘EPDM发泡橡胶层I、尼龙66支架层、自粘EPDM发泡橡胶层II、隔离纸,自粘EPDM发泡橡胶层Ⅱ、隔离纸,自粘EPDM发泡橡胶层I的下面依次设有一层尼龙66支架层、一层自粘EPDM发泡橡胶层Ⅱ、一层隔离纸,尼龙66支架层侧面的中间位置设有一个固定用的卡扣。     

氯化聚乙烯橡胶/废旧三元乙丙橡胶胶粉共混发泡材料的研究

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。     

发泡剂对EPDM发泡橡胶性能的影响

采用热空气自由发泡制备EPDM发泡橡胶,研究发泡剂品种和用量对其性能的影响。结果表明,以发泡剂OBSH、AC和H制备EPDM发泡橡胶时,它们的最佳用量分别为10份、15份和10份;当发泡剂用量为10份时,以发泡剂OBSH制备的EPDM发泡橡胶发泡倍率最大。观察发泡橡胶内部结构发现,用发泡剂OBSH制备的EPDM的发泡橡胶内部泡孔结构较均匀、孔径最小。     

EPDM预成型模压发泡材料的研制

本文采用快压型炭黑N550作为橡胶补强填料,研究了加工工艺、发泡剂添加量、硫化体系对EPDM发泡材料的影响。研究表明:①采用三段塑炼工艺进行EPDM预成型模压发泡,物料混炼更均匀;②当发泡剂用量高于2份时,制备出的EPDM发泡材料是开、闭孔混合结构的发泡材料;③当硫化体系用量增加8%时,有较好的交联程度,力学性能较好,硫化过程与发泡过程匹配较好,橡胶海绵具有较好的微孔结构。     

LDPE/EVA鞋底发泡材料的研究

讨论了发泡剂偶氮二甲酰胺(AC)、橡胶(EPDM、NBR)、填料超细碳酸钙(CaCO3)用量对LDPE／EVA发泡材料性能的影响，研制出发泡材料密度及力学性能满足运动鞋中底要求的配方。结果表明：AC用量为6份时，发泡材料密度达到0．078g／cm^3；EPDM有效改善了发泡材料的强度，当EPDM加入15份时，发泡材料密度和力学性能优异；超细CaCO3可以提高LDPE／EVA／NBR发泡材料的强度，当超细CaCO3用量为30份时，发泡材料性能较好。     

发泡橡胶吸音材料

以前用玻璃棉和聚氨酯发泡材料做吸音材料，但这类吸音材料只对高频率有效，对低频率则效果不大，该文作者用EPDM橡胶作发泡材料，其吸音率的峰值可以在不同频率范围内根据设计要求而发生位移，大大提高了吸音要求。     

POE/EPDM TPV的结构与性能研究

采用动态硫化法制备了聚烯烃弹性体（POE）三/元乙丙橡胶（EPDM）热塑性硫化胶（TPV）,并对其力学性能、微相结构和应力松弛进行了研究。结果表明,POE/EPDM TPV的应力-应变曲线具有典型的弹性体特征;较POE而言,POE/EPDM TPV具有较低硬度和永久形变;EPDM橡胶相的粒径在几微米到几十微米之间,较均匀地分散在POE连续相中;TPV的应力松弛速率随EPDM用量的增加而降低,随应变的增大而加快。     

发泡膨胀阻燃橡胶的制备及其性能研究

以EPDM 9950C/EPDM 4869C并用胶作基胶，加入发泡剂﹑膨胀石墨﹑阻燃剂及其他橡胶助剂，通过微波挤出硫化生产线制备了发泡膨胀阻燃橡胶；探讨了生胶并用比﹑发泡体系﹑膨胀石墨用量和阻燃体系对发泡膨胀阻燃硫化橡胶性能的影响。结果表明，EPDM 9950C/EPDM 4869C并用比为80/20时，发泡膨胀阻燃硫化橡胶力学性能较好，密度较小；加入发泡助剂能促进发泡剂分解，生成小密度发泡膨胀阻燃橡胶；膨胀石墨用量为35～45份时，发泡膨胀阻燃硫化橡胶综合性能较优；采用阻燃剂RL-CT时，发泡膨胀阻燃橡胶阻燃效果最佳，达到了V-0级。     

Mechanical Properties of Silicone Rubber Enhanced Microcellular EPDM Foams Based on Supercritical CO2 Foaming Technology

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.     

Aramid fiber reinforced EPDM microcellular foams: Influence of the aramid fiber content on rheological behavior,mechanical properties,thermal properties,and cellular structure

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.     

硅橡胶／三元乙丙橡胶泡沫合金性能研究

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。     

EVA/EPDM/IR/IR共混发泡材料的研制与应用

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。     

Improvement of the acoustic and mechanical properties of sponge ethylene propylene diene rubber/carbon nanotube composites crosslinked by subsequent sulfur and electron beam irradiation

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.     

用甲基丙烯酸原位改性纳米碳酸钙填充三元乙丙橡胶Ⅲ.应力软化效应和应力弛豫

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。     

Various nano-particles influences on structure,viscoelastic, Vulcanization and mechanical behaviour of EPDM nano-composite rubber foam

ABSTRACT

In 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.     

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

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.     

Design of ethylene-propylene-diene monomer foam and its double-layer composite for improving sound absorption properties via experimental method and theoretical verification

In this work, the ethylene-propylene-diene monomer (EPDM) foam was fabricated via 4-4′-oxobisbenzenesulfonyl hydrazide (OBSH) and phenolic resin (PF) in an effort to prepare the sound-absorbing composite which has excellent sound absorption at the medium and low frequency. For single-layer EPDM foams, cell morphology showed a certain pattern, causing the peak of the sound absorption coefficient move to a higher frequency and the peak value reached a maximum of about 0.75 as the OBSH content increased. In addition, with the foaming temperature increasing, the cell morphology had a different tendency and the peak of the sound absorption coefficient moved first to the higher frequency and then to the lower frequency due to the vulcanization reaction. Compared with the single-layer EPDM foams, the sound absorption curve of the double-layer composite made of the single-layer EPDM foam and pure EPDM sheet with cavities moved to a lower frequency by about 400 Hz. The theoretical calculation method was used to verify the accuracy of the experimental results. This work provided a simple approach to control the sound absorption property of EPDM foamed material and its double-layer composite through from an experimental and theoretical perspective.