采用不同粒径的Ni粉与硅橡胶（110型）按质量比2.4∶1.0制成Ni/硅橡胶复合材料,分别测量了其压敏导电性及介电性质,并结合扫描电镜照片对其微观导电机制进行了分析。结果表明随着填料Ni粉粒径的减小,Ni/硅橡胶复合材料的直流电阻率对外加压强更加敏感：在低压强下,粒径为74、48和18μm的样品的电阻率随压强的变化率分别为1.73×104、2.59×104和3.71×104Ω.m/kPa。样品直流电阻率陡降的区域随粒径的减小向压强较小的方向移动,显示出复合材料的渗流阈值与填充粒子的粒径有关：粒径越小,渗流阈值也越小。Ni/硅橡胶复合材料的交流电导率、介电常数、介电损耗均随填料Ni粉粒径的减小而变大：Ni粉粒径为18μm的Ni/硅橡胶复合材料的电导率约为10-2S.m-1,比74μm粒径样品的电导率（约10-7S.m-1）提高了5个数量级;对应的介电常数由约102提高到约103。改变填料Ni粉粒径可以有效地调节复合材料的弹性和压敏、电输运特性。
Ni/silicone rubber composites with nickel powders of different particle sizes were prepared at a filler/ silicone rubber mass ratio of 2.4∶1.0.The piezoresistivity and the dielectric properties of the composite samples at room temperature were measured.The mechanism of electric conduction is discussed together with the SEM images of the samples.The results show that piezoresistivity of Ni/silicone rubber composite is enhanced by reducing the filler particle size： at low pressures,the pressure derivative of resistivity,of samples prepared with Ni powders of particle size 74,48 and 18μm is 1.73×104、 2.59×104 and 3.71×104Ω·m/kPa respectively.The sharp drop in resistivity shifts to the low pressure end as the filler particle size decreases,suggesting that the percolation threshold of Ni/silicone rubber composites decreases with reduced filler particle size.AC conductivity,dielectric constant and dielectric loss of Ni/silicone rubber composites all increase with the decrease of particle size： the conductivity of the sample with filler particle diameter 18μm reaches about 10-2 S·m-1,which is five orders of magnitude greater than that of the sample with filler particle diameter 74μm（about 10-7S·m-1）,and the corresponding dielectric constant is also increased from about 102 to about 103.Elasticity,piezoresistivity,and electronic transport properties of the composite can be adjusted by changing the filler particle size.
参考文献
| [1] | Mu Minfang, Walker Amanda M, Torkelson John M, Winey Karen I. Cellular structures of carbon nanotubes in a polymer matrix improve properties relative to composites with dispersed nanotubes[J]. Polymer, 2008, 49(5): 1332-1337. |
| [2] | Azulay D, Eylon M, Eshkenazi O, Toker D, Balberg M, Shimoni N, Millo O, Balberg I. Electrical-thermal switching in carbon-black-polymer composites as a local effect [J]. Phys Rev Lett, 2003, 90(23): 2366011-2366014. |
| [3] | Bloor D, Donnelly K, Hands P J, Laughlin P, Lussey D. A metal-polymer composite with unusual properties [J]. J Phys D, 2005, 38(16): 2851-2860. |
| [4] | Martin J E, Anderson R A, Odinek J, Adolf D, Williamson J. Control.ling percolation in field- structured particle composites: Observations of giant thermoresistance, piezoresistanee, and chemiresistance [J]. Phys Rev B, 2003, 67(9) : 094207-094217. |
| [5] | 常方高,王少祥,杨枫,张娜,马恒,宋桂林.一种压敏超导-金属-高分子复合材料功能材料[J].功能材料,2008,39(11):1847-1849. |
| [6] | 韩宝忠,韩宝国,张坤,马凤莲,冯涛.镍粉粒子形态对硅橡胶基复合材料拉敏性的影响[J].稀有金属材料工程,2008,37(12):2226-2230. |
| [7] | 宋桂林,房坤,常方高.Ni/硅橡胶复合材料的压敏与介电特性[J].复合材料学报,2009,26(2):37-40. |
| [8] | Chang F G, Yang F, Zhang N, Wang S X, Song G L. Enhanced piezoresistivity in Ni - silicone rubber composites [J]. Chinese Phys B, 2009, 18(2): 652-657. |
| [9] | 河南师范大学.一种压敏导电橡胶及其制备方法:中国,101108916[P].2008-01-23. |
| [10] | 魏志刚,汤文成.复合材料网格结构模态分析的均匀化等效建模[J].复合材料学报,2008,25(2):188-193. |
| [11] | Essam J W. Percolation theory [J]. Rep Prog Phys, 1980, 43 (7) : 833-912. |
| [12] | Jing X, Zhao W, Lan L. The effect of particle size on electric conducting percolation thresholdin polymer/conducting particle composites [J]. Journal of Materials Science Letters, 2000, 19(5) : 377-379. |
| [13] | He Da, Ekere N N. Effect of particle size ratio on the conducting percolation threshold of granular conductive- insulating composites [J]. J Phys D: Appl Phys, 2004, 37: 1848-1852. |
| [14] | Chang F G, Saunders G A, Lambson E F, et al. Temperature and frequency dependencies of the complex dielectric constant of poly(ethylene oxide)under hydrostatic pressure [J]. Journal of Polymer Science Part B: Polymer Physics, 1996, 34(3) 425-433. |
| [15] | Mahboob Syed, Prasad G, Kumar G S. Impedance and a. c. conductivity studies on Ba(Nd0.2Ti0.6Nb0.2)O3 ceramic prepared through conventional and microwave sintering route [J]. Bulletin of Materials Science, 2006, 29(4): 347-355. |
| [16] | Bergman David J, Imry Yoseph. Critical behavior of the complex dielectric constant near the percolation threshold of a heterogeneous material [J]. Phy Rev Lett, 1977, 39(19): 1222-1225. |
| [17] | Almond D P, Vainas B. The dielectric properties of random R- C networks as an explanation of the 'universal' power law dielectric response of solids [ J]. Journal of Physics: Condensed Matter, 1999, 11(46): 9081-9093. |
| [18] | 宋修宫,王继辉,高国强.RTM工艺中树脂固化温度与介电性能[J].复合材料学报,2007,24(1):18-21. |
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