【作者】 杨文武；

【导师】 钱家盛；

【作者基本信息】 安徽大学 ， 应用化学， 2011， 硕士

【摘要】 橡胶基纳米复合材料是以橡胶为基体,复合材料体系中至少有一种组分其一维尺寸要在100nm以下的新型纳米复合材料,在当前材料领域,橡胶基纳米复合材料将是研究的热点之一。纳米氮化硅(Si3N4)粉体是一种性能优异的结构陶瓷材料。由于它具有热膨胀系数小、密度适中、硬度大、弹性模量高及热稳定性、自润滑性、化学稳定性和电绝缘性好等特点因而被广泛应用。纳米Si3N4陶瓷粉体在使用时非常容易团聚,这是因为纳米Si3N4陶瓷粉体的比表面积非常大,同时具有高表面自由能,这些都使得其在橡胶等聚合物体系中难于分散,从而导致橡胶纳米复合材料优异性能不能完全发挥。大分子表面改性剂能有效改善橡胶基体和纳米颗粒之间的相容性、促进纳米颗粒有效分散。本工作针对大分子表面改性剂的合成、纳米Si3N4的表面改性、在橡胶基体中的分散以及纳米复合材料的综合性能等方面进行了研究。1.采用溶液接枝聚合法制备了低分子量液体聚丁二烯-γ-甲基丙烯酰氧基丙基三甲氧基硅烷(LMPB-g-KH570)接枝共聚物,使用红外(FTIR)、核磁(1H-NMR)、热分析(TGA, DSC)等表征手段对接枝共聚物的结构进行分析；结果表明,LMPB-g-KH570是接枝共聚物；LMPB-g-KH570的接枝率为27.13%-35.07%(质量分数wt%),接枝共聚物的热稳定性良好。VPO结果表明LMPB-g-KH570的数均分子量Mn=4025,符合大分子表面改性剂的数均分子量在3000-10000之间的要求。2.使用合成的大分子表面处理剂LMPB-g-KH570对纳米Si3N4进行表面修饰,采用FTIR、TGA、沉降试验、透射电镜(TEM)、接触角和表面能等测定手段对改性后的粉体进行分析；结果表明LMPB-g-KH570与纳米Si3N4发生化学键合,纳米Si3N4颗粒表面包覆一层有机层,LMPB-g-KH570的利用率为63.67%,且其化学修饰利用率可以达到30.66%；纳米Si3N4经表面修饰后,纳米Si3N4颗粒的表面能降低,在乙酸乙酯中分散均匀,有效阻止了纳米Si3N4的团聚；纳米Si3N4经表面改性后,表面亲水性减弱,亲油性增加,表面自由能由未改性的112.32J/M2降低到70.12J/M2。3.将大分子表面处理剂]LMPB-g-KH570改性后的纳米Si3N4粉体填充丙烯酸酯橡胶(ACM),制备了纳米Si3N4/ACM复合材料。利用RPA-8000、SEM、TEM等手段对纳米复合材料的微观结构和性能进行了分析和评价。结果表明,改性纳米Si3N4能有效改善复合材料的微观界面相互作用并提高橡胶的硫化和力学性能。在RPA动态力学性能扫描测试生胶及混炼胶性能的试验中,弹性模量G’和损耗因子tanδ均随频率和应变的升高,分别显示出降低和增大的规律,频率和应变的适当提高可以改善其加工性。与纯ACM相比,添加2.0份改性后纳米Si3N4/ACM复合材料正硫化时间降低38秒,拉伸强度提高24.8%,撕裂强度提高3.39%。更多还原

【Abstract】 Rubber Nanocomposites is new type of polymeric composite in which one component has the dimension less than 100nm at least, and it is one of the focuses on which intensively studies in the field of materials. Silicon nitride (Si3N4) is a high-performance engineering ceramic material. Recently, silicon nitride ceramics has been applied widely because it has moderate density, high hardness and elastic modulus. In addition, it has high thermal stability, chemical resistance and good electrical insulation. But nano-Si3N4 is easily agglomerate; the reason is that nano-Si3N4 has much surface area and high surface activity. All of these will cause the nano-Si3N4 powder to be dispersed difficultly. So the excellent properties of nano-powder/rubber composite materials can not exhibit adequately. This work focused on synthesization of macromolecule surface coupling agent, surface modification of nano-Si3N4 powder, dispersion of nano-Si3N4 powder in the rubber matrix, and the complex properties of rubber nanocomposites.1. Low molecular weight liquid polybutadiene-y-methacryloxypropyl trimethoxy silane (LMPB-g-KH570) were synthesized by solution polymerization. The structure of LMPB-g-KH570 was investigated by FT-IR,1H-NMR, TGA, DSC et al. The results indicated that the KH570 were respectively grafted onto LMPB. The graft ratio of LMPB-g-KH570 was from 27.13% to 35.07%(wt%). The results of TGA and DSC show that LMPB-g-KH570 graft copolymer had good thermal stability. Its average molecular weight was measured by VPO. The Mn value of LMPB-g-KH570 was calculated as 4025, meeting the requirement that optimum number-averaged molecular weight should be in the range of 3000-10000.2. Nano-Si3N4 was modified macromolecular coupling agents LMPB-g-KH570. The properities of modified nano-Si3N4 and raw nano-Si3N4 were characterized by FT-IR, TGA, TEM et al. FT-IR, TGA and DSC indicated that LMPB-g-KH570 bonded covalently on the surface of Si3N4 nanoparticles, and an organic coating layer was formed. The reaction condition was optimized by the dispersion stabilization. TEM revealed that modified nano-Si3N4 possessed good dispersibility in ethyl acetate and the diameter was about 100nm. TGA also indicated that the using efficiency of LMPB-g-KH570 was 63.67%, and chemical using efficiency reach 30.66%. Contact angle and surface free energy investigated that the hydrophile was weakened and the hydrophobicity was enhanced. After modification with graft copolymer (LMPB-g-KH570), the surface free energy of nano-Si3N4 decreased sharply from 112.32 to 70.12 J/M2.3. Nano-Si3N4/acrylate rubber (ACM) composite were prepared by blending techniques, the microstructure of nanocomposites were analyzed and discussed by RPA-8000, SEM and TEM. The results showed that modified nano-Si3N4 effectively improved the micro-interface interaction of nanocomposite and the performance of vulcanized and mechanical properties of the ACM. The results show that in the RPA dynamic mechanics performance scanning test on the raw rubber andmixed performance test, modulus of elasticity G’ and loss fact or tanδalong with frequency and strain elevating, separately demonstrated reduces and increases, enhance the frequency and strain suitable may improve its workability. Compared with pure ACM, the curing time of ACM nanocomposites reduced 38 seconds, the tensile strength increased 24.8%, tear strength increased 3.39%.更多还原