炭黑填充粒子对导电硅橡胶压阻特性的影响

阐述了复合型导电高分子材料的导电机理,分析了4种导电炭黑填充量对导电硅橡胶导电特性的影响,实验分析了相同导电填料、不同质量分数情况下的导电硅橡胶压阻特性,分析了相同质量分数、不同导电填料对复合材料压阻特性的影响。研究表明,随着炭黑填充量的不断增加,复合材料体积电阻率均呈下降趋势;4种炭黑填充的导电硅橡胶渗流阀值较接近;导电硅橡胶的电阻-压力变化规律符合隧道效应理论模型;为保证导电硅橡胶具有良好的压阻特性,应根据原料控制好导电炭黑的添加量。     

流体作用下导电硅橡胶的压阻特性及弛豫特性

实验制备了不同导电硅橡胶试样,搭建了用于测试流体作用下导电硅橡胶压阻特性的试验平台并设计了测试方法,分别研究了在一定范围内液体静压下导电硅橡胶的体压阻特性、表面压阻特性、弛豫特性及在气压作用下的表面压阻特性。研究表明,在液体静压下,6%乙炔炭黑/2%纳米SiO2并用的试样所表现出的压阻性能最优,而纳米改性材料的添加与材料厚度的增大可以缩短导电硅橡胶的电阻弛豫时间;添加改性材料后,导电硅橡胶在气压作用下的压阻特性曲线明显优于单独添加乙炔炭黑的情况,而且随着材料厚度的增加其压阻特性有较好的提升。     

烯丙基离子液体修饰炭黑/硅橡胶复合材料的压阻特性

为改善炭黑在硅橡胶中的界面性质,通过机械研磨法,采用1-烯丙基-3-甲基-咪唑氯盐对炭黑进行表面修饰,再与硅橡胶混炼制备炭黑填充硅橡胶柔性复合压阻材料,研究了修饰炭黑对复合材料的导电渗流和压阻行为、压阻松弛和循环特性的影响。扫描电镜表明,与未经修饰的炭黑对比,修饰炭黑在硅橡胶基体中形成炭黑离子凝胶结构。由于炭黑离子凝胶的增塑作用及在靠近时相互排斥和在远离时相互吸引作用,离子液体修饰炭黑/硅橡胶复合材料较炭黑/硅橡胶具有更敏感的正压阻效应和更短的压阻松弛时间,并且循环压缩测试结果表明离子液体修饰炭黑/硅橡胶复合材料电阻变化具有更好的可重复性。     

改性材料对炭黑填充压敏硅橡胶导电性能的影响

针对纳米材料具有改善导电橡胶填料分散性、体系压阻特性及稳定性的效果,通过将2%的纳米白炭黑(SiO2)、非纳米白炭黑、纳米α-三氧化二铝(α-Al2O3)3种改性材料与不同含量炭黑并用填充硅橡胶,制备了导电硅橡胶。测试并研究了导电硅橡胶的渗滤阈值、压阻特性及压阻范围。讨论了导电硅橡胶的迟滞及弛豫性能。通过扫描电镜照片,分析了纳米材料对导电硅橡胶的改性机理。研究表明,添加纳米材料后,导电硅橡胶的渗滤阈值降低,压阻范围及压力敏感区间明显扩大;炭黑在导电硅橡胶中分散更加均匀;导电硅橡胶电阻弛豫时间显著缩短并且迟滞性降低。     

导电橡胶复合材料压力传感特性研究

基于填充型导电高分子柔性复合材料压阻效应,研究导电橡胶压力传感过程中的特殊性能。确定了实验材料与合成工艺,实验室制备出了炭黑填充型导电硅橡胶柔性复合材料,研究了复合材料压力传感特性主要影响因素。分别采用气相法和液相法对炭黑粒子进行表面氧化改性,可有效提高炭黑在基体材料中的分散性,从而改善和提高压力传感性能。双组分基体材料压阻特性优于单组分材料,粘度越大,压阻特性越好,压力传感过程中的电阻弛豫时间越短,电阻迟滞特性系数越小。炭黑与多壁碳纳米管并用,可增强复合材料力敏效应,提高复合材料压力传感性能。     

碳纤维填充对导电硅橡胶压阻效应及电阻蠕变行为的影响

将导电粒子添加到绝缘硅橡胶中制备出具有压阻效应的导电硅橡胶,它是一种新型压力传感器用材料。选用3种不同长度的碳纤维作为导电填料,高温硫化硅橡胶作为基体制备导电橡胶,同时在100μm长碳纤维填充导电橡胶中引入镍包铝球形粒子形成复合填料。分析了导电硅橡胶的渗流特性、压阻效应与电阻蠕变行为,发现纤维长度和纤维添加量对导电橡胶的压阻行为有显著影响:纤维长度增大,导电橡胶的渗流阈值变小;导电橡胶的压阻效应在渗流区间明显;球形镍包铝可以削弱导电橡胶的电阻蠕变程度。     

导电炭黑填充硅橡胶的电阻温度系数

以炭黑(CB3100)为导电相,硅橡胶为基质制备导电复合材料。研究导电橡胶中炭黑质量分数对电阻温度系数的影响,并用填料对电阻温度系数的影响。以隧道效应理论为基础,给出了导电炭黑填充橡胶的电阻温度系数计算模型,结合实验得到温度对导电炭黑/硅橡胶电阻温度系数的影响主要体现在对其电阻率的影响;基体的体积热膨胀提高复合材料的电阻率,提高了正电阻温度系数;炭黑粒子间的隧道效应降低复合材料的电阻率,增强了负电阻温度系数;在炭黑/硅橡胶中加入少量碳纳米管,利用碳纳米管和炭黑的协同补强效应,使复合材料的导电性和稳定性提高。     

炭黑填充型导电橡胶的压力/温度特性研究

分析了导电橡胶的压阻效应和温度效应,实验制备了导电橡胶试样,并研究了试样添加不同导电粒子后的压阻特性和温度特性。研究表明,导电橡胶添加不同导电材料时呈现出不同的温度特性,随温度的升高,单独添加乙炔炭黑的导电橡胶在30～70℃之间呈现负温度效应,在70～120℃之间呈现正温度效应;乙炔炭黑与N472并用的导电橡胶随温度的升高呈现正温度效应;添加纳米Al2O3的导电橡胶随温度的升高呈现正温度效应和负温度效应。探讨了压力变化时电阻率与温度的相关性,分析了产生不同温度特性的主要原因。     

双导电相硅橡胶力敏材料的制备与电性能分析

为了获得具有较好压阻稳定性和重复性的力敏复合材料,在炭黑/硅橡胶复合体系中加入纳米氧化钌,完善补充导电相的同时加固硅橡胶交联网络。采用溶剂热还原法制备金属钌纳米颗粒,在空气中热氧化,得到尺寸为数十纳米的氧化钌颗粒;采用溶剂共混的方法制备炭黑/硅橡胶共混胶,用研磨分散的方法将纳米二氧化钌加入炭黑/硅橡胶共混胶中,硫化成型后得到氧化钌(RuO2)-炭黑(CB)/硅橡胶(MVQ)双导电相复合材料。采用自建的压阻性能测试系统测试了复合材料的压阻性能,测量结果表明,CB/MVQ体系中加入一定用量的RuO2其压阻重复性变好,压阻蠕变性得到改善;用扫描电镜、透射电子显微镜分析了复合材料的微观结构,并用能谱分析结合电子衍射图证明了纳米氧化钌以纳米结构存在于复合材料中,丰富和完善了炭黑导电网络,加固了硅橡胶交联网络,这些因素是导致压阻重复性提高的主要因素。     

炭黑填充型导电复合材料的压阻计算模型及实验验证

为研究新型传感器材料,在通用有效介质理论的基础上,提出了炭黑填充型导电复合材料的压阻特性数学计算模型,定量地得出炭黑颗粒的基本特征参数、体积分数和聚合物基体的弹性模量在复合材料压阻规律中的影响。分别以硅橡胶和高密度聚乙烯为基体相,三种不同粒径的炭黑为导电相,制备了炭黑填充型复合材料,对计算模型进行了实验验证。在炭黑颗粒分布均匀、炭黑体积分数在渗流阈值附近和外加压力≤2 MPa等三个边界条件下,数学计算模型与实验结果基本吻合,且压力-电阻变化规律一致。      

气相生长碳纤维增强水泥基复合材料的制备及性能

研究了脱油沥青(De-oiled asphalt)基气相生长碳纤维(VGCFs)增强水泥基复合材料的制备方法及其性能。以脱油沥青作原料,采用化学气相沉积法(CVD)制备出气相生长碳纤维,以此纤维制备水泥基功能复合材料。结果表明:低含量VGCFs的碳纤维增强水泥基复合材料具有良好的抗压强度和导电性能,在VGCFs的掺量由0增至0.6 %范围内,随着VGCFs掺量的增加,碳纤维增强水泥基复合材料的电阻率下降,抗压强度提高。当VGCFs为0.4 %时,VGCFs水泥基复合材料电阻率降低2个数量级,从3.25 ×105 Ω·cm 降为1.49 ×103 Ω· cm ,抗压强度提高28.8 %,为最佳掺量。      

Effect of compressive strain on electrical resistivity of carbon black-filled cement-based composites

This paper investigates the strain sensing properties of carbon black (CB)-filled cement-based composites which were prepared with 120 nm CB. A linear relationship between the fractional change in resistivity and compressive strain was observed for cement-based composites containing a large amount of CB, suggesting that this kind of composite was a promising candidate for strain sensors used in concrete structures. Tunneling effect theory and percolation theory are employed to interpret the conductivity and electromechanical properties of CB-filled cement-based composites.     

炭黑/聚丙烯-聚(苯乙烯-乙烯/丁烯-苯乙烯)复合材料的介电性能和压阻性能

为了制备柔性较好的聚合物基压阻材料,利用熔融共混法制备了炭黑/聚丙烯-聚(苯乙烯-乙烯/丁烯-苯乙烯)(CB/PP-SEBS)复合材料,并研究了CB含量对CB/PP-SEBS复合材料介电性能和压阻性能的影响。结果表明:随着CB含量的增加,CB/PP-SEBS复合材料的介电常数、介电损耗及电导率均提高;CB/PP-SEBS复合材料发生导电逾渗时,CB的含量为12.2wt%;在CB/PP-SEBS复合材料发生弹性形变时,由于外力破坏了CB的导电网络,复合材料的电阻随着应变的增大而增大;循环压阻测试结果显示,在弹性变形区CB/PP-SEBS复合材料的电阻随着应变呈现周期性变化。研究结果可为制备具有稳定电阻变化的聚合物基压阻材料提供借鉴。     

表面改性和复合工艺对金属纤维/聚合物复合材料性能的影响

以不锈钢纤维为导电填料,分别与ABS和PP复合,制得了电磁屏蔽用导电高分子复合材料。考察了表面改性和复合工艺对金属纤维／聚合物复合材料性能的影响。结果表明,用不同表面处理剂处理不锈钢纤维后,随纤维表面张力增加,复合材料的电阻率增加。使用母料法工艺可以有效地改善金属纤维在聚合物基体中的分散,从而提高复合材料的导电性能和电磁屏蔽性能。     

A comparative study of the coated filler method and the admixture method of powder metallurgy for making metal–matrix composites

Copper–matrix composites were made by powder metallurgy (PM). The reinforcements were molybdenum particles, silicon carbide whiskers and titanium diboride platelets. The coated filler method, which involves a reinforcement coated with the matrix metal, was used. In contrast, conventional PM uses the admixture method, which involves a mixture of matrix powder and reinforcement. For all the composite systems, the coated filler method was found to be superior to the admixture method in providing composites with lower porosity, greater hardness, higher compressive yield strength, lower coefficient of thermal expansion (CTE), higher thermal conductivity and lower electrical resistivity, though the degree of superiority was greater for high than low reinforcement contents. In the coated filler method, the coating on the reinforcement separated reinforcement units from one another and provided a cleaner interface and stronger bond between reinforcement and matrix than the admixture method could provide. The highest reinforcement content attained in dense composites (<5% porosity) made by the coated filler method was 70 vol% Mo, 60 vol% TiB2 and 54 vol% SiC. The critical reinforcement volume fraction above which the porosity of composites made by the admixture method increases abruptly is 60% Mo, 42% TiB2 and 33% SiC. This fraction increases with decreasing aspect ratio of the reinforcement. Among Cu/Mo, Cu/TiB2 and Cu/SiC at the same reinforcement volume fraction (50%), Cu/Mo gave the lowest CTE, highest thermal conductivity and lowest electrical resistivity, while Cu/SiC gave the greatest hardness and Cu/TiB2 and Cu/SiC gave the highest compressive yield strength. Compared to Cu/SiC, Cu/TiB2 exhibited much higher thermal conductivity and much lower electrical resistivity. This revised version was published online in November 2006 with corrections to the Cover Date.     

Effect of extensional strain on the resistivity of electrically conductive nitrile-rubber composites filled with carbon filler

The resistivity and mechanical properties of nitrile-rubber based conductive composites filled with short carbon fibres (SCFs) and mixed filler system (SCF + carbon black) are studied as functions of the extensional strain and the strain rate. It has been observed that both strain and strain rate have a strong influence on the resistivity of the composites. The sensitivity of the change in resistivity against the strain and strain rate depends on the concentration as well as the type of conductive filler. SCFs impart higher conductivity to the composite than a blend of SCFs and carbon black at the same level of loading parts per hundred of rubber (p.h.r.). Composites filled with a mixed filler system show high mechanical properties in contrast to those of SCF-filled composites. The change in resistivity with the degree of strain is less pronounced in mixed-filler-filled composites than in only carbon-fibre-filled composites. The mechanical properties of the composites are dependent on the polymer-filler interaction whereas change in resistivity is dependent on the transient arrangement of the conducting components in the polymer matrix. A good correlation exists between mechanical and electrical response to the strain sensitivity.     

低频聚苯胺/硅橡胶复合材料屏蔽效能的分析

分析了以掺杂态聚苯胺为填料、硅橡胶为基体的复合材料的导电性以及其在3-1500MHz频段下的屏蔽效能。研究结果表明,随着聚苯胺加入量的增加,体电阻率明显下降,屏蔽效能稳定提高。当加入重量比为100：100时,屏蔽效能在16-19．3dB,体电阻率与原橡胶相比下降12个数量级。     

Thermal,electrical, mechanical and fluidity properties of polyester-reinforced concrete composites

Polyester particles in concrete are preferred because they provide thermal, chemical and water resistance. In this study, thermal conductivity, electrical resistivity, mechanical strength and water resistance properties of concretes containing polyester granules such as flame-retardant polyester, cationic dyeable polyester and polyester with a low melting point-filled concrete have been analyzed using a full factorial design via Minitab^® version 17. The effect of the most influential factors on thermal conductivity of polyester aggregate reinforced concrete composite has been determined as an interaction between the cationic dyeable and low-melt–point polyester. This mixture is suitable for production of thermal insulating concrete. Moreover, it is concluded that cationic dyeable polyester is the highest corrosion- and water-resistant product among the polyesters used in this study. The recovery rate of 33.94% in the thermal conductivity and 214.89% in the electrical resistivity of polyester-reinforced concrete composites has been obtained with a 28-day compressive strength loss of 41.94% according to the reference concrete in the full factorial design application. These results indicate that the polyester-reinforced concrete composites are quite effective in achieving thermal and corrosion resistance concrete but with noticeable compressive strength loss.     

纳米复合聚合物电解质的新型制备方法及其性能

以含有纳米SiO₂ 的聚乙二醇二丙烯酸酯( PEGDA) 为单体, 加入液态电解质, 通过紫外光辐射固化制备了凝胶态纳米复合聚合物电解质(NCPE) 。含有纳米SiO₂ 的PEGDA 单体是以水性硅溶胶为原料, 通过一个溶剂交换过程制备的, 与此同时纳米SiO₂ 的表面通过加入甲基丙烯酰氧丙基三甲氧基硅烷(MAPTMS) 进行改性, 使其表面具有可以参与光固化的丙烯酸酯基团。与用不含纳米粒子的PEGDA 单体制备的凝胶态聚合物电解质相比, 纳米复合聚合物电解质的电导率更高, 尤其是电化学稳定性和界面稳定性有明显提高。      

C／C复合材料石墨化度与导电性能的关系

研究了五种具有二维及准二维结构的炭/炭复合材料在不同石墨化度下各自的电阻率的变化,分析了引起这些变化的原因。结果表明,在所研究的石墨化度范围内,随着石墨化度的升高,材料的电阻率都呈下降的趋势,且电阻率ρ随石墨化度g的变化符合线性关系ρ=a