摘要
导电橡胶复合材料具有良好的导电性、延展性、弹性、环境密封性和耐介质腐蚀性，在军用和民用等诸多领域都得到了广泛应用。早期制备高导电橡胶，采用银粉作为导电填料，但银粉密度大且价格昂贵，从而使银粉填充型导电橡胶的应用受到限制。当前研究主要集中于探索新型导电填料来取代银粉。本文在前人工作的基础上，以自制PS微球、商用玻璃纤维和玻璃微珠为模板，运用化学镀方法分别制备了镀银、镀镍系列复合粒子。之后，以该类复合粒子为导电填料，硅橡胶为基体，制备了相应的导电橡胶复合材料。对化学镀工艺以及导电橡胶制备工艺进行了详细而系统的研究。主要工作及其结论如下：
(1)以聚乙烯吡咯烷酮为分散剂，偶氮二异丁腈为引发剂，采用分散聚合方法制备了粒径在2.0μm左右、表面光滑、分散均匀的聚苯乙烯(PS)微球。以自制PS微球、商用玻璃纤维和玻璃微珠为模板，运用化学镀方法制备了镀银系列复合粒子。结果显示，所获得的PS/Ag复合粒子的最佳体积电阻率为1.60×10~(-4)·cm，玻璃纤维/Ag复合粒子为1.36×10~(-4)·cm，玻璃微珠/Ag复合粒子为3.14×10~(-4)·cm。以所制备的玻璃纤维/Ag、玻璃微珠/Ag复合粒子为导电填料，制备了填充型导电橡胶复合材料。研究了导电粒子添加量和一、二段硫化对导电橡胶导电和力学性能的影响。结果显示，随着导电填料添加量的增大，导电橡胶的导电性能提高而力学性能降低。二段硫化法对于降低橡胶复合材料的体积电阻率具有十分明显的作用，所得导电橡胶导电性能较一段硫化法提高1～2个数量级。当导电填料添加量为300份时，玻璃纤维/Ag复合粒子填充型导电橡胶样品的体积电阻率降至0.006·cm；玻璃微珠/Ag复合粒子填充型导电橡胶样品的体积电阻率降至0.009·cm，显示了优异的导电性能。
(2)采用化学镀方法，以自制PS微球、商用玻璃纤维和玻璃微珠为模板，制备了镀镍系列复合粒子。结果显示，PS/Ni的最佳制备工艺为：PS/NiCl_2·6H_2O质量比为4:7，氨水用量为30 mL·L~(-1)，NiCl_2·6H_2O浓度为0.21 mol·L~(-1)，PdCl_2浓度为0.006 mol·L~(-1)。玻璃纤维/Ni复合粒子的最佳制备工艺为：玻纤/NiCl2·6H2O质量比为2:1；氯化镍/柠檬酸三钠质量比为2:1；氨水用量为8 mL·L~(-1)；反应温度为75℃。在最佳工艺条件下所得复合粒子的体积电阻率分别为0.03·cm和0.0063·cm、采用玻璃纤维/Ni复合粒子的最佳制备工艺，获得的玻璃微珠/Ni复合粒子的体积电阻率为0.0091·cm。以所制备的玻纤/Ni、玻珠/Ni复合粒子为填料制备了导电橡胶复合材料。研究了一、二段硫化方法对橡胶样品体积电阻率的影响。结果显示，二段硫化后，镀镍复合粒子有严重的氧化现象，从而导致橡胶的导电性能下降。因此，对于镀镍粒子填充型导电橡胶，不适宜进行二段硫化。在一段硫化工艺条件下所得玻纤/Ni复合粒子填充型导电橡胶的体积电阻率为0.041·cm，玻珠/Ni复合粒子填充型导电橡胶为0.08·cm。
The conductive rubber composite materials have a wide range of applications in militaryand civilian fields due to their unique merits, such as good conductivity, ductility, elasticity,airtightness, and corrosion resistance. The previous preparation of high-conductive rubberuses silver powder as conductive filler. However, the application of such rubber is greatlylimited due to the high price of silver. Currently, many researches are mainly focused on newtypes of conductive fillers to replace silver powder. Therefore, the fabrication of highlyconductive silver-based composite by electroless plating method was widely implemented andcarried out all over the world. Based upon the work done by former researchers, wesynthesized silver- and nickel-based composite particles using polystyrene (PS)microspheres、commercial glass fibers, and glass beads as the templates. Then, the conductiverubber composites were prepared using the above composite particles as conductive filler andsilicone rubber as matrix material, respectively. The parameters influencing the electrolessplating process and conductive rubber preparation process were systematically investigated,and main work and conclusions were summarized as following:
(1) The polystyrene microspheres with the average size of 2.0μm were prepared by thedispersion polymerization technique with polyvinylpyrrolidone (PVP) as a dispersing agentand azobisisobutyronitrile (AIBN) as an initiator. The silver-based composite particles wereprepared through electroless plating method with self-made PS microspheres, commercialglass fibers, and glass beads as templates. Theρvvalues of the PS/Ag, glass fibers/Ag, andglass beads/Ag composite particles were 1.60×10~(-4)·cm, 1.36×10~(-4)·cm, and 3.14×10~(-4)·cm, respectively. The conductive rubber composites were prepared with self-made glassfibers/Ag, glass beads/Ag composite particles as fillers. The conductivity and mechanical properties of such rubber were studied. The results showed that the electrical conductivityincreased but the mechanical properties decreased with the increase of conductive filleramount. The post vulcanization has a remarkable function to reduce theρvof conductiverubber, and the conductivity of the rubber can increase 1～2 orders of magnitude compared tothat treated by one segment vulcanization. Theρvvalues of the conductive rubbers, whichwere filled with glass fibers/Ag and glass beads/Ag composite particles with amount of 300phr, respectively, would decrease to 0.006 and 0.009·cm. It implied that such rubberpossessed excellent conductivity.
(2) The nickel-based composite particles were prepared through electroless platingmethod with self-made PS microspheres, commercial glass fibers, glass beads as templates.The optimum preparation process of PS/Ni composite particles was described as following:the mass ratio of PS to NiCl_2·6H_2O was 4:7, NH_3·H_2O concentration of 30 mL·L~(-1),NiCl2·6H2O concentration of 0.21 mol·L~(-1), and PdCl2concentration of 0.006 mol·L~(-1). Theoptimum preparation process of glass fibers/Ni composite particles was as following: themass ratio of glass fibers to NiCl_2·6H_2O was 2:1, the mass ratio of NiCl2·6H2O toC_6H_5O_7Na_3·6H_2O was 2:1, NH_3·H_2O concentration of 8 mL·L~(-1), and reaction temperature of75℃. Theρvof the PS/Ni, glass fibers/Ni composite particles were 0.03·cm and 0.0063·cm, respectively. Theρvof the glass beads/Ni composite particles prepared with theoptimum preparation process for glass fibers/Ni composite particles was 0.0091·cm .Theconductive rubber composites were prepared with self-made glass fibers/Ni, glass beads/Nicomposite particles as fillers. The effect of the one segment and post vulcanization on theρvof the conductive rubber were investigated. The results showed that the nickel-basedcomposite particles were seriously oxided and lead to the decreasedρv. So it was unease tocarry out post vulcanization. Theρvvalues of the conductive rubber filled with glass fibers/Ni,glass beads/Ni composite particles were 0.041·cm, and 0.08·cm, respectively, under theone segment vulcanization.
引文
[1]陈晶. Fe@Ag复合粒子的制备及其性能研究[A].武汉:武汉理工大学, 2010. 5.
[2]丁世敬,赵跃智,葛德彪.电磁屏蔽材料研究进展[J].材料导报, 2008, 22(4): 30~33.
[3]王一龙,官建国,邵寒梅,等.电磁屏蔽材料用银包玻璃微珠核-壳粒子的制备及其性能[J].硅酸盐学报, 2008, 36(3): 301~305.
[4] R.K. Rao Chepuri, M. Vijayan, D.C. Trivedi. EMI shielding: Methods and materials-Areview [J]. Journal of Applied Polymer Science, 2009, 112(4): 2073~2086.
[5] Y.J. Hu, H.Y. Zhang, F. Li. Investigation into electrical conductivity and electromagneticinterference shielding effectiveness of silicone rubber filled with Ag-coated cenosphereparticles[J]. Polymer Testing, 2010, 29(5): 609~612.
[6] N.H.H. Abu Bakar, J. Ismail, M. Abu Bakar. Synthesis and characterization of silvernanoparticles in natural rubber[J]. Materials Chemistry and Physics, 2007,104(2-3): 276~283.
[7] Z.M. Chen, T. Gang, K Zhang. Ag nanoparticles-coated silica-PMMA core-shellmicrospheres and hollow PMMA microspheres with Ag nanoparticles in the interiorsurfaces[J]. Colloids and Surfaces A: Physicochem. Eng. Aspects, 2006, 272: 151~156.
[8]翁国文.实用橡胶配方技术[M].北京:化学工业出版社, 2008. 331.
[9]郭威,吴行,郑振忠,等.导电炭黑/天然橡胶力学和导电性能研究[J].绝缘材料,2011, 44(1): 58~60.
[10]黄英,李郁忠,周传友,等.导电硅橡胶导电性和电热性的研究[J].橡胶工业, 2002,49(2): 77~82.
[11]张继华,任灵,王立峰,等.炭黑填充导电硅橡胶的结构与性能[J].宇航材料与工艺, 2011, 2: 79~82.
[12]柳学义,陈闯,杨艳宇.炭黑填充型硅橡胶复合材料的制备及其性能研究[J].绝缘材料, 2012, 45(1): 15~18.
[13] K.G. Princy, H.R. Josep, C. SudhaKartha. Studies on conductivity of nitrile rubber and itsblends with NR, EPDM, and PVC[J]. Plastics, Rubber and Composites, 2002, 31(3):114~118.
[14]翟俊学,董凌波,赵树高.石墨／炭黑／EPDM复合材料的性能研究[J].橡胶工业,2011, 58: 591~595.
[15]张洪雁,曹寿德,王景鹤.高性能橡胶密封材料[M].北京:化学工业出版社, 2007.166.
[16] K. De. Anisotropy in mechanical and dynamic properties of composites based on carbonfiber filled thermoplastic elastomeric blends of natural rubber and high density polyethylene[J]. Polymer Engineering & Science , 1992, 32(4): 971~979.
[17] A.K. Chaudhuri, S.K. De Pal. Electrical conductivity of short carbon fiber-reinforcedpolychloroprene rubber and mechanism of conduction[J]. Polymer Engineering & Science,1992, 32(6): 448~456.
[18] R. Verdejo, M.A. Lopez-Manchado, L. Valentini. Carbon nanotube reinforced rubbercomposites[J]. Rubber Nanocomposites: Preparation, Properties, and Applications, 2010,27:147~168.
[19] S. Gang, W.H. Zhong, X.P. Yang, et al. Processing and material characteristics of acarbon-nanotube reinforced natural rubber[J]. Macromolecular Materials and Engineering,2007, 292(9): 1020~1026.
[20] L.D. Perez, M.A. Zuluaga, T. Kyu, et al. Preparation, characterization, and physicalproperties of multiwall carbon nanotube/elastomer composites[J]. Polymer Engineering &Science, 2009, 49(5): 866~874.
[21] C. McClory, S.J. Chin, T. McNally. Cheminform Abstract: Polymer/ Carbon NanotubeComposites. ChemInform, 2009, 40(52): 238.
[22] S.X. Santos, T.G. Cavalheiro, Christopher M.A. Brett. Analytical potentialities of carbonnanotube/Silicone rubber composite electrodes: determination of propranolol[J].Electroanalysis, 2010, 22(23): 2776~2783
[23] K. TaeMin, G.H. Kim. Uncross-linked polypropylene (PP)/ ethylene-propylene-diene(EPDM)/multi walled carbon nanotube (MWCNT) and dynamically vulcanized PP/EPDM/MWCNT nanocomposites[J]. Polymers for Advanced Technologies, 2011, 22(12): 2273~2278
[24] B.M. Cho, G.H. Kim. Effect of the processing parameters on the surface resistivity ofacrylonitrile-butadiene rubber/multiwalled carbon nanotube nano-composites[J]. Journal ofApplied Polymer Science, 2010, 116(1): 555~561.
[25]黄勇,陈善勇,刘俊红.导电复合橡胶研究进展[J].贵州化工, 2009, 34(4): 14~17.
[26]王文福.导电金属填料的制备方法[J].世界橡胶工业, 2001, 28(6): 9~11.
[27]雷海军,宫文峰,武晶,等.金属填料对高导电硅橡胶性能的影响[J].橡胶工业,2005, 52(11): 667~669
[28]雷海军,翟广阳,宫文峰.导电填料对电磁屏蔽橡胶性能的影响[J].特种橡胶制品,2008, 29(2): 30~33.
[29]闫军,崔海萍,杜仕国,等．偶联剂对环氧-铜粉复合导电涂料导电性能的影响[J]．弹性体, 2003, 13(4): 18~21．
[30] Y. Li, K.S. Moon, C.P. Wong, et al．Electrical property improvement of electricallyconductive adhesives through in-situ replacement by short-chain difunctional acids[J]．IEEETransactions on Components and Packaging Technologies, 2006, 29(1): 173~178．
[31]刘海清,田英良,毛倩瑾,等.镍基导电涂料微波反射性能研究[J].电镀与涂饰,2011, 30(4): 71~73．
[32] H.T. Hai, J.G. Ahn, D.J. Kim, et al. Developing process for coating copper particles withsilver by electroless plating method [J]. Surface and Coatings Technology, 2006, 201(6):3788.
[33]许锐,周康生,王飞.化学镀法制备银包覆超细铜粉反应工艺研究[J]．武汉理工大学学报, 2008, 30(1): 24~27．
[34]许锐,周康生,胡敏艺.化学镀法制备核壳型银-铜双金属粉[J]．材料科学与工艺,2009, 17(3): 333~335．
[35]吴懿平,吴大海,袁忠发,等.镀银铜粉导电胶的研究[J].电子元件与材料, 2005,24(4): 32.
[36]梅冰,乔学亮,王洪水,等.微米级铜粉化学镀银及抗氧化性分析[J].材料保护,2006, 39(9): 28.
[37]李传友,王群,王澈,等.化学镀法制备Ag/Al复合粉末[J].功能材料, 2010, 9(41):1525~1528.
[38]耿新玲,苏正涛,钱黄海,等.镀银镍粉填充型导电硅橡胶的性能研究[J].橡胶工业, 2006, 7: 417~419.
[39]曹晓国,张海燕. Ag包覆Fe3O4复合粉体的制备及其性能研究[J].功能材料, 2007,10(38): 1655~1657.
[40]王一龙,李维,章桥新,等.羰基铁粉/银核-壳粒子及其复合材料的制备与电磁特性[J].高等学校化学学报, 2010, 31(10): 1934~1939.
[41]管登高,孙传敏,孙遥,等.化学镀制备电磁屏蔽用导电复合填料的研究进展[J].材料导报A, 2011, 25(4): 28~32.
[42] S.C. Tang, L. Chen, S. Vongehr, et al. Heterogeneous nucleation and growth of silvernanoparticles on unmodified polystyrene spheres by in situ reduction [J]. Surface andCoatings Technology, 2010, 256: 2654~2660.
[43] J.H. Zhang, H.Y. Liu, Z.L. Wang, et al. A solvent-assisted route for coating polystyrenecolloids with Ag and the corresponding hollow Ag spheres[J]. Materials Letters, 2007, 61:4579~4582.
[44]刘惠玉,陈东,唐芳琼,等.化学镀法制备银壳聚苯乙烯微球[J].物理化学学报,2006, 22(5): 644~648.
[45] D. Song, J.D. Zhou, W. J, et al. A novel activation for electroless plating on preparingNi/PS microspheres[J]. Materials Letters, 2009, 63: 282~284.
[46] H.J. Yu, G.Y. Xu, X.M. Shen, et al. Preparation of monodisperse Ni/PS spheres andhollow nickel spheres by ultrasonic electroless plating [J]. Surface & Coatings Technology,2007, 201: 7174~7179.
[47]孙文泽,刘颖,连利仙,等. Ni/PS核壳结构纳米复合微球的制备及磁性能[J].高分子材料科学与工程, 2010, 26(6): 122~125.
[48]邹华,赵素合,田明,等.镀银玻璃微珠/硅橡胶导电复合材料导电性能的影响因素[J].橡胶工业, 2009, 56(8): 459~463.
[49]黄征,官建国,王一龙.玻璃微珠/银核壳纳米复合粒子的制备及表征[J].硅酸盐学报, 2004, 34(7): 882~886.
[50]王一龙,官建国,章桥新,等.复合导电橡胶的制备及性能[J].武汉理工大学学报,2008, 30(10): 1~4.
[51]彭祖雄,张海燕,陈天立,等.镀银玻璃微珠/炭纤维填充导电硅橡胶的电磁屏蔽性能[J].高分子材料科学与工程, 2011, 27(1): 88~91.
[52]沈玲,邹华,田明,等.高导电镀银玻璃微珠/硅橡胶复合材料的结构与性能[J].合成橡胶工业, 2006, 29(5): 375~379.
[53]耿新玲,苏正涛,米志安,等.镀银玻璃微珠填充导电硅橡胶的研制[J].特种橡胶制品, 2006, 27(2): 20~21.
[54]胡圣飞,张冲,赵敏,等.空心微珠热碱液活化化学镀银[J].粉末冶金材料科学与工程, 2010, 15(1): 79~83.
[55]王宇,张骁勇,毛丽,等.空心玻璃微珠化学镀银的研究[J].材料科学与工程学报,2004, 22(5): 753~756.
[56] Q.Y. Zhang, M. Wu, W. Zhao. Electroless nickel plating on hollow glass microspheres[J]. Surface & Coatings Technology, 2010, 27(3): 1164~1167.
[57]邵谦,杨玉香,葛圣松,等.空心玻璃微珠表面无钯活化化学镀镍工艺研究[J].功能材料, 2007, 12(38): 2001~2003.
[58]王海燕,张翠欣,于升学,等.空心微珠表面化学镀Ni-P合金及其吸波性能研究[J].表面技术, 2010, 39(6): 63~65.
[59] T.X Liang, W.L Guo, Y.H Yan, et al. Electroless plating of silver on graphite powdersand the study of its conductive adhesive [J]. International Journal of Adhesions, 2008,28(1~2): 55.
[60] W. Lin, X.R. Xi, C.S. Yu. Research of silver plating nano-graphite filled conductiveadhesive[J]. Synthetic Metals, 2009, 159(7~8): 619.
[61] W.F. Sun, G.H. Chen, L.L. Zheng. Electroless deposition of silver particles on graphitenanosheets [J]. Scripta Material, 2008, 59(10): 1031.
[62]曹鼎,李芝华.超声处理化学镀法制备镀银玻璃纤维[J].粉末冶金材料科学与工程,2009, 14(6): 422~426.
[63]卢健体,李芝华,曹鼎.无钯活化化学镀银玻璃纤维的制备[J].稀有金属材料与工程, 2010, 39: 27~30.
[64] L.B. Li, B. Liu. Study of Ni-catalyst for electroless Ni-P deposition on glass fiber[J].Materials Chemistry and Physics, 2010, 128: 303~310.
[65] X.A. Li, X.J. Han, Y.J. Tan,et al. Preparation and microwave absorption properties ofNi-B alloy-coated Fe3O4particles[J]. Journal of Alloys and Compounds, 2008, 464: 352~356.
[66] Z.C. Xu, Y.L. Hou, S.H. Sun. Magnetic core/shell Fe3O4/Au and Fe3O4/Au/Ag Nanopa-rticles with tunable plasmonic properties[J]. Journal of the American Chemical Society, 2007,129: 8698 ~8699.
[67]武晓威,冯玉杰,刘延坤,等.钡铁氧体表面化学镀Ni-P合金的制备及性能[J].哈尔滨工业大学学报, 2010, 42(4): 584~587.
[68]吕百龄.实用橡胶手册[M].北京:化学工业出版社, 2010.
[69]耿新玲,刘君,任玉柱,等.导电硅橡胶研究进展[J].航空材料学报, 2006, 26(3):283~288.
[70] M. T. Polley. Carbon black for highly conductive rubber[J], Rubber Chemistry andTechnology. 1957, (30): 170~176.
[71]刁广照.超导电炭黑填充硅橡胶的制备与性能[A].山东:山东大学, 2007. 4.
[72] P. Seng. Fluctuation-induced tunneling conduction in dispordered materials[J]. PhysicalReview B, 1980, 21(6): 2180~2195.
[73] P. Sheng, E.K. Sichell, J.I. Gittleman. Fluctuation-induced tunneling conduction incarbon/ polyvinylchlchloride composites[J]. Physical Review Letters, 1978, 40(18):1197~1200.
[74]李法华.功能型橡胶材料及制品[M].北京:化学工业出版社, 2008.
[75]杨遂芳.航空轮胎胎面胶导静电性能的改进[J].特种橡胶制品, 1993, 14(1): 24~28.
[76]李慎贵.医用电极导电性能的研究[J].特种橡胶制品, 1994, 15(6): 8~11.
[77]谢琼珍.导电硅橡胶键性能的介绍[J].特种橡胶制品, 1987, 3: 31~32.
[78]田微,顾云飞.化学镀银的应用与发展[J].电镀与环保, 2010, 30(3): 4~7.
[79] D.H. Chen, S.R. Wang. Protective agent-free synthesis of Ni-Ag core-shell nanoparticles[J]. Materials Chemistry and Physics, 2006, 100: 468~471.
[80] T.X. Liang, W.L. Guo, Y.H. Yan, et al. Electroless plating of silver on graphite powdersand the study of its conductive adhesive [J]. International Journal of Adhesion & Adhesives,2007, 27: 55~58.
[81]赵科雄,席生岐,吴宏京,等. Cu/Ag核壳复合粉末的制备与表征[J].稀有金属材料与工程, 2008, 37(10): 1852~1855.
[82]耿新玲,苏正涛,钱黄海,等.镀银镍粉填充型导电硅橡胶的性能研究[J].橡胶工业, 2006, 53: 417~419.
[83]史博,章永化.原子转移自由基聚合制备端磺酸基PS及其与表面阳离子化的SiO2静电自组装研究[J].材料导报, 2008, 9(22): 119~124
[84]张继阳,邹华,田明,等.镀银玻璃微珠/硅橡胶导电复合材料逾渗值的研究[J].特种橡胶制品, 2007, 28(1): 19~22.
[85]卢金荣,吴大军,陈国华.聚合物基导电复合材料几种导电理论的评述[J].塑料,2004, 33(5): 43~47.
[86] W. Zhao, Q.Y. Zhang, T. Chen, et al. Preparation and thermal decomposition of PS/Nimicrospheres [J]. Materials Chemistry and Physics, 2009, 113(1): 428~434.
[87] J.L. Jiang, H.Q. Lu, L.X. Zhang, et al. Preparation of monodisperse Ni/PS spheres andhollow nickel spheres by ultrasonic electroless plating[J]. Surface and Coatings Technology,2007, 201(16-17): 7174~7179.
[88]李丽波,刘波,吴宝华.玻璃纤维表面化学镀镍的工艺研究[J].稀有金属材料与工程, 2011, 40(增2): 360~364.