混合型泡孔结构硅橡胶泡沫的制备与压缩性能

采用化学发泡的方法制备了开孔-闭孔混合型泡孔结构的硅橡胶泡沫材料,研究了密度对硅橡胶泡沫压缩性能的影响。结果表明:随着材料密度的增加,相同应变所对应的应力增大,应力-应变曲线明显上移,ε_(0.32)随着密度增加而减小,拟合的线性方程为ε_(0.32)=-101.008ρ+84.286,相关系数R=-0.998;压缩应力松弛率随着密度增加而线性增大。     

四针状氧化锌晶须对硅橡胶泡沫材料性能的影响

研究了四针状氧化锌晶须对硅橡胶泡沫材料的组织结构、力学和压缩应力松弛性能等的影响。结果表明:四针状氧化锌晶须的加入可以明显提高硅橡胶泡沫材料的密度、硬度和拉伸强度,降低其泡孔的尺寸,优化泡孔的分布;且随加入量的增多,其效果越明显;该材料的压缩应力松弛性能随四针状氧化锌晶须的加入有明显的降低,且加入量越多,降低也越明显。     

技术文摘

发泡剂对EPDM发泡橡胶性能的影响 【摘要】：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、     

微孔发泡PP的拉伸性能及失效机理研究

通过改变拉伸速率及拉伸应变,对微孔发泡PP材料拉伸过程中的泡孔变形情况进行了观测,分析了在不同拉伸速率下泡孔的变形过程及对力学性能的影响,并采用扫描电子显微镜(SEM),研究了微孔发泡PP材料的拉伸失效机理。     

聚氨酯泡沫吸声材料的制备及性能研究

利用一步法制备聚氨酯泡沫吸声材料,探究了配方和发泡工艺对泡沫材料性能的影响,对材料的吸声系数、力学强度和微观结构进行了测试与表征。结果表明,当发泡剂为8g、匀泡剂为1.5g、反应温度为30℃时,聚氨酯泡沫的吸声系数为0.42;经130℃处理10h后,聚氨酯吸声材料具有较好的综合性能,其吸声系数和力学强度分别为0.47和0.68 MPa。SEM观测显示,吸声材料形成了分布均匀有利于吸声的开孔-闭孔共存体系。     

高孔隙率、小孔径泡沫铝的制备及压缩性能

以纯铝为基体材料、钙为增黏剂、TiH2为发泡剂制备了高孔隙率(80%)不同孔径的泡沫铝;研究了对发泡剂进行表面氧化处理、增黏搅拌时间、发泡剂加入量和发泡时间对泡沫铝孔结构的影响,并对不同孔径的泡沫铝进行了压缩试验。结果表明:对发泡剂进行氧化处理可以减缓其释放氢的速度,经过相同时间发泡后可获得孔径更小的泡沫铝,但要获得相同孔隙率的泡沫铝,则经氧化处理发泡剂的加入量应比未经氧化处理的大;延长增黏搅拌时间有利于获得小孔径泡沫铝;其他条件相同时,泡沫铝的孔径和孔隙率随着发泡时间的延长而增大;孔隙率相近时,孔径小的泡沫铝,单向压缩应力应变屈服平台较高,吸能能力也较大。     

微孔发泡挤出成型技术

介绍微孔发泡技术的工艺过程,以超临界CO<,2>作为物理发泡剂,对低密度聚乙烯(LDPE)进行了微孔发泡的研究,并分析了加工工艺因素(温度、压力)等对制品泡孔尺寸和密度的影响:泡孔直径随挤出压力的增加而减小,随压力降速率的增大而减小;而适当提高温度有利于减小泡孔直径、增加泡孔密度.     

中空玻璃微珠改性PP泡沫复合材料的发泡效果和力学性能

先用硅烷偶联剂(KH550)对中空玻璃微珠(HGB)进行表面预处理,然后采用型内二次发泡工艺制备了中空玻璃微珠(HGB)改性聚丙烯(PP)泡沫复合材料,研究了HGB质量分数对泡沫复合材料发泡效果、界面结合性能及力学性能的影响。结果表明:HGB的加入能显著改善发泡效果,当HGB质量分数为15%时,能够获得泡孔分布均匀、泡孔直径细小的闭孔结构,泡沫复合材料的力学性能最佳,冲击韧度、抗弯强度和压缩强度分别为25.6kJ·m-2,11.2 MPa和17.6MPa;KH550表面预处理增强了HGB与PP基体之间的界面结合性能,且对泡壁强度起到了显著增强效果。     

硅橡胶泡沫材料与刚性面准静态摩擦接触数值分析研究

基于有限元方法模拟研究硅橡胶泡沫材料与刚性接触面在准静态摩擦接触过程中的力学性能。基于多尺度方法建立与实际泡孔结构相符的细观模型-单胞泡孔模型。考虑泡孔壁之间摩擦因素,计算获得细观模型的力学性能。将细观模型性能通过数据传递机制植入宏观模型,据此模拟研究硅橡胶泡沫材料与刚性加载面相互作用时的压缩载荷和结构变形情况,并讨论界面摩擦因数对该材料力学性能的影响。模拟结果表明,摩擦因数对硅橡胶泡沫材料的准静态单轴压缩力学性能影响较小,且所得模拟结果与实验结果吻合良好。     

微孔发泡聚丙烯(PP)的性能的研究

通过“二次开模法”制备了聚丙烯(PP)微孔发泡材料,对拉伸中泡孔的变形过程进行了分析,对几种不同密度的PP 微孔泡沫塑料进行了缺口冲击实验,研究了泡孔直径及密度对材料冲击性能的影响规律,并通过断口形貌的电镜分析,研究了PP微孔发泡材料的破坏机制及增韧机理。     

Experimental study of cure process of foam rubber: observation of cell structure

Experimental study has been made during cure process of SBR/NR foam rubber. Rubber sample with 30 mm thick, made up by stacking thin rubber sheets in layers, was packed in a metal mold, and peroxide cure was performed by transient heat conduction. Rubber heating time was changed in several steps in order to study the effects of the cure time on the blowing characteristics. Also swelling test was conducted in order to study the relation between the cell structure and the crosslink density. Typical temperature field of one-dimensional, transient heat conduction was observed, and results of the observation studies showed that the cell structure changed depending on both the position from the heating surface and the heating time, and two extreme cell structure, open-cell foam, and closed-cell foam, was clearly observed. Image analyses of the cell structure showed that the porosity distribution increased with the increase of the distance from the heating surface, and the porosity was lower for longer heating time at a same position. Average area of the foam almost took similar results for the result of the porosity, and these various quantities were correlated to the crosslink density.     

航空用苯基硅橡胶生胶的合成及性能研究

为探究生胶结构与应用性能之间关系，设计合成不同苯硅比(Ph/Si)的二苯基硅橡胶生胶和甲基苯基硅橡胶生胶。生胶的DSC分析表明：在苯基改性的硅橡胶生胶中，含苯基硅氧链节的摩尔数量是影响硅橡胶低温结晶、熔融的主要因素；同样苯硅比5%的二苯基硅橡胶生胶是结晶橡胶，而甲基苯基硅橡胶生胶则是非结晶橡胶。硅橡胶硫化胶的物理力学性能分析表明：苯基硅橡胶经热空气老化试验后拉伸强度和拉断伸长率得到较显著的提高，苯基硅氧链节结构形式对耐热影响不显著。硫化胶的低温DMTA分析表明：苯基硅橡胶硫化胶的玻璃化转变温度与苯硅比有关，而与苯基硅氧链节的结构形式关系不大，且随苯硅比的增大，玻璃化转变温度向高温方向移动。压缩耐寒系数分析表明：在相同的苯硅比5%下，非结晶的甲基苯基结构硅橡胶具有更优异的低温性能，结晶的二苯基硅橡胶由于低温结晶使其在较长时间压缩状态下失去橡胶弹性。     

金属发泡橡胶复合密封板材的研制

通过模压成型工艺,成功研制了一种高品质金属发泡橡胶复合密封板材,该密封板材具有优异的压缩回弹性能、极好的抗蠕变松弛性能,以及与密封面极好的配合性和长期耐压密封性能,可广泛替代软木橡胶、橡胶、抄取密封材料等应用于机动车、工业缝纫机、仪器仪表、玻璃钢管道等的密封要求.     

液压减振器橡胶气带性能测试与分析

发泡橡胶具有较好的耐热老化性、耐油性和耐压缩永久变形性能,在液压减振器储油腔中采用发泡橡胶气带替代气腔,是解决减振器气穴现象和油液乳化现象的有效方法。发泡橡胶特性对减振器阻尼作用有很大的影响,通过发泡橡胶在液压油内压缩实验,用回归分析方法得到其压力-体积变化规律,进一步利用 AMESim软件完成对采用橡胶气带减振器的仿真分析。减振器测试结果表明,发泡橡胶的压力-体积变化规律较好的反映了气带在减振器中的工作情况,对液压减振器用发泡橡胶气带的设计有一定的指导意义。     

Morphology and viscoelastic properties of sealing materials based on EPDM rubber

In this applicative study, the ratio of active and inactive filler loadings was the prime factor for determining the dynamic–mechanical behaviour of ethylene–propylene–diene monomer rubbers. Scanning electron microscopy was used to study the structure of reinforced dense and microcellular elastomeric materials. The effects of filler and blowing agent content on the morphology of composites were investigated. Microcellular samples cured in salt bath show smaller cells and uniform cell size compared with samples cured in hot air. Dynamic–mechanical thermal analysis showed appreciable changes in the viscoelastic properties by increasing active filler content, which could enable tailoring the material properties to suit sealing applications.     

PP/POE/滑石粉复合发泡体系的制备与性能研究

本文通过二次开模法和松退法注射成型工艺制备出PP/POE/滑石粉复合发泡体系。研究了两种成型方法对该复合发泡体系的力学性能和密度的影响,并用扫描电镜对其微观形貌进行了表征。结果表明,对PP/POE/滑石粉复合发泡体系的力学性能而言,采用二次开模法比松退法要好。由SEM扫描照片可知,二次开模法比松退法制得的复合发泡体系具有更高的泡孔成核率,同时泡孔直径较小,分布较均匀。     

Study of Al-alloy foam compressive behavior based on instrumented sharp indentation technology

The stress-strain relation of aluminum (Al) alloy foam cell wall was evaluated by the instrumented sharp indentation method. The indentation in a few micron ranges was performed on the cell wall of Al-alloy foam having a composition of Al-3wt.%Si-2wt.%Cu-2wt.%Mg as well as its precursor (material prior to foaming). To extract the stress-strain relation in terms of yield stressσ _y, strain hardening exponentn and elastic modulusE, the closed-form dimensionless relationships between load-indentation depth curve and elasto-plastic property were used. The tensile properties of precursor material of Al-alloy foam were also measured independently by uni-axial tensile test. In order to verify the validity of the extracted stress-strain relation, it was compared with the results of tensile test and finite element (FE) analysis. A modified cubicspherical lattice model was proposed to analyze the compressive behavior of the Al-alloy foam. The material parameters extracted by the instrumented nanoindentation method allowed the model to predict the compressive behavior of the Al-alloy foam accurately.     

Pneumatic Stripping Device of Rubber Ripple Pipe

The rubber ripple pipe is usually to be used for the dust shield and be made by blowing or molding generally. It is easier for molding cure when the pipe is made by molding. The key is how to remove the ripple pipe that tightly hooped on the core. Thispaper presents a pneumatic stripping device of rubber ripple pipe.     

Analysis of spatial cross‐correlations in multi‐constituent volume data

We investigate spatial cross‐correlations between two constituents, both belonging to the same microstructure. These investigations are based on two approaches: one via the measurement of the cross‐correlation function and the other uses the spatial distances between the constituents. The cross‐correlation function can be measured using the fast Fourier transform, whereas the distances are determined via the Euclidean distance transform. The characteristics are derived from volume images obtained by synchrotron microtomography. As an example we consider pore formation in metallic foams, knowledge of which is important to control the foam production process. For this example, we discuss the spatial cross‐correlation between the pore space and the blowing agent particles in detail.