【作者】 夏茹；

【导师】 朱清仁； 章于川；

【作者基本信息】 中国科学技术大学 ， 高分子化学与物理， 2008， 博士

【摘要】 利用性能优异的纳米材料开发特种和功能性新型的橡胶纳米复合材料已经成为橡胶研究领域的重要方向。但是由于纳米微粒具有大比表面和高表面能,容易团聚,特别是在橡胶中较在热塑性塑料中的分散更为困难,很难达到理想的分散效果,导致纳米效应难以在橡胶纳米复合材料的宏观性能上充分体现。因此目前对于橡胶纳米复合材料的研究集中在对纳米材料的表面改性方法、纳米材料在橡胶基体中的分散状态和机理、纳米材料的增强机理以及复合材料结构与性能的关系等方面。本论文以三类汽车用橡胶制品（橡胶减震器油封、汽车橡胶耐磨胶管、橡胶止动件）为切入点,深入研究了陶瓷纳米材料的表面修饰改性以及橡胶陶瓷纳米复合材料的制备和性能。主要包括以下几部分的内容:1.根据陶瓷纳米材料的基本特性,选择合肥开尔纳米材料有限公司等离子弧气相法生产的纳米非晶氮化硅和纳米六方氮化铝为研究对象,研究了这两种陶瓷纳米粉体的相关性质及其表面结构。采用FTIR和XPS分析比较了纳米氮化硅、微米氮化硅以及纳米氮化铝在潮湿的空气中不同时间下氧化、水解的情况。为进一步深入研究陶瓷纳米粉体的表面修饰改性奠定了基础。2.针对不同的基体橡胶和陶瓷纳米粉体复合体系,设计、合成了三种偶联剂,用于纳米Si₃N₄和纳米AlN的表面修饰改性,以提高纳米粉体与基体橡胶的相容性和纳米粉体在基体橡胶中的分散性。通过自由基溶液共聚法合成了大分子偶联剂MAA-BA-AN三元共聚物和MMA-BA-VTES三元共聚物,研究了引发剂浓度和链转移剂浓度对三元共聚物分子量的影响;在常温下通过化学沉淀法合成了纳米甲基丙烯酸锌（ZDMA）粉体,考察和研究了搅拌速率、滴加速率、溶液浓度等影响因素。通过红外、核磁、GPC、DSC和TGA等对合成的产物进行了表征。3.采用上述合成的偶联剂对陶瓷纳米粉体进行表面改性后通过FTIR,XPS,TGA,TEM,SEM,纳米粒度分析,沉降试验和接触角测定等研究探讨其表面改性效果。用MAA-BA-AN三元共聚物对纳米Si₃N₄进行表面修饰改性;用MMA-BA-VTES三元共聚物分别改性纳米Si₃N₄和纳米AlN;利用纳米ZDMA对纳米Si₃N₄进行直接包覆改性和原位接枝聚合改性,并进行比较。4.设计试制可用于工业化纳米粉体的表面改性的纳米粉体热雾化包覆处理设备——断续式纳米粉体表面改性机,使大分子偶联剂溶液能够形成亚微米级雾滴,与悬浮状态的纳米粉体充分接触,提高其包覆率,使处理后的纳米材料在橡胶基体中能够达到有效分散。5.改进传统的填料与橡胶混炼工艺,探讨了不同的混炼工艺条件对陶瓷纳米粉体在橡胶中分散性的影响。通过炭黑分散度测定仪、橡胶加工分析仪以及TEM研究发现,采用密炼机两段混炼工艺使陶瓷纳米粉体在橡胶基体中得到有效分散,可以充分发挥填充材料的纳米效应。6.设计制备三种橡胶陶瓷纳米复合材料,分别为:三元共聚物MAA-BA-AN改性纳米Si₃N₄后填充丁腈橡胶;三元共聚物MMA-BA-VTES改性纳米AlN后填充天然/丁苯橡胶;纳米ZDMA原位接枝聚合改性纳米Si₃N₄后填充三元乙丙橡胶。用二段密炼的混炼工艺研究制备上述三种橡胶陶瓷纳米复合材料,根据对橡胶陶瓷纳米复合材料力学性能、耐油性能、耐磨性能、耐老化性能等的测试结果研究探讨了大分子偶联剂的数均分子量对表面改性效果的影响,橡胶纳米复合材料凝聚态结构与性能的关系及其橡胶配件制品性能提高的机理。7.研究制备三种橡胶汽车配件产品。用三元共聚物MAA-BA-AN改性纳米Si₃N₄/丁腈橡胶复合材料研制汽车减震器油封;用纳米ZDMA原位接枝聚合改性纳米Si₃N₄/三元乙丙橡胶复合材料研制汽车用耐磨胶管;用三元共聚物MMA-BA-VTES改性纳米AlN/天然丁苯橡胶复合材料研制汽车橡胶止动件。对上述三种产品进行了相关性能测试和台架试验,结果均达到了国际先进水平。综上所述,本文创造性地将陶瓷纳米粉体（纳米Si₃N₄和纳米AlN）应用到橡胶纳米复合材料的制备,根据不同的复合体系设计合成了新型的大分子偶联剂并对陶瓷纳米粉体进行表面改性,成功实现了纳米粉体在橡胶基体中的均匀分散。结果证实纳米Si₃N₄和纳米AlN不仅能够对橡胶实现增强增韧,同时还能显著提高其他性能,如耐油、耐磨等性能。此外,首次设计试制出可用于工业化纳米粉体表面改性的纳米粉体热雾化包覆处理设备——断续式纳米粉体表面改性机。以上的论文工作为突破纳米分散的技术瓶颈,实现橡胶纳米复合材料的工业化探索出一条成功的可行之路。更多还原

【Abstract】 Using nanomaterials with excellent performance to develop special and functional new rubber nanocomposite materials has become an important research direction in the field of rubber. But the nanoparticles are more difficult to disperse homogenously in the rubber matrix than the thermoplastics due to their high specific surface area and high surface free energy. So the research of rubber nanocomposites is focused on nanomaterials’ surface modification, nanomaterials’ dispersion in the rubber matrix, the strengthening mechanism of nanomaterials and the relationship between structures and properties of rubber nanocomposites, etc.This paper aims at three categories of automotive rubber products （oil seal of rubber shock absorbers, wear-resistant rubber hoses and rubber stopper）. Surface modification of ceramic nano-materials and the preparation and performance of the rubber nanocomposites are in deep investigation. The work could be summarized as follows:1. The nano-sized amorphous silicon nitride and hexagonal aluminum nitride which are produced by Hefei Kaier Nanotechonlogy Development Co., Ltd. were chose as the research object and this two ceramic nanopowder’s surface structure were studied. FTIR and XPS analysis were used to compare the oxidation and hydrolysis reaction of nano-silicon nitride, micro-silicon nitride and nano-aluminum nitride when open in the humid air for a certain time. of the situation. The present study may laid the foundation for a further investigation of ceramic nanopowder’s surface modification.2. Three coupling agent which could be used for surface modification of nano-Si₃N₄ and nano-AlN were designed and synthesized for different rubber /ceramic nanocomposite system to enhance homogenous dispersion and compatibility between nanoparticles and rubber matrix. Macromolecular coupling agent MAA-BA-AN tercopolymer and MMA-BA-VTES tercopolymer were both synthesized by free radical solution copolymerization method. The impact of initiator and transfer agent’s concentration on the tercopolymer’s molecular weight were discussed. Nano-zinc methacrylate was synthesized at room temperature through chemical deposit method. The factors influencing the size and structure of nano-ZDMA such as stir rate, dropping rate, solution concentration were studied in detail. The structure and morphology of nano-ZDMA were characterized by FTIR, NMR, GPC, DSC and TGA.3. The nano-ceramic powders were modified with the coupling agent mention above. The silicon nitride nanoparticles were modified with MAA-BA-AN tercopolymer and MMA-BA-VTES tercopolymer, the aluminum nitride nanoparticles were modified with MMA-BA-VTES tercopolymer, the zinc methacrylate nanopowder were modified with direct coating method and in-situ graft polymerization method respectively. The result of surface modification were characterized by FTIR, XPS, TGA, TEM, SEM, nano-size analysis, the settlement test and contact angle determination.4. Design and fabricate a thermal fogging nanopowder’s surface modification equipment, intermittent surface modification machine, which can be applied in industrial production. The macromolecular coupling agent solution can form sub-micron droplet with this machine, then well-mixed with nano-powder which suspended in mixing chamber, thus the coating efficiency is enhanced and the modified nanopowder could achieving homogenous dispersion in the rubber matrix.5. The influences of different mixing process on nanoparticles’ dispersion in the rubber matrix were discussed. The two-step internal mixing process was confirmed as the effective mixing process to achieving homogenous dispersion in the rubber matrix based on Carbon Black Dispersion Analyzer, Rubber Processing Analyzer and TEM.6. Three kinds of rubber/ ceramic nanocomposites are designed and prepared by two internal mixing process, which are as follows: nano-silicon nitride modified with tercopolymer MAA-BA-AN/ NBR nanocomposite; nano-aluminum nitride modified with tercopolymer MMA-BA-VTES / NR/SBR nanocomposite; nano-silicon nitride modified with nano-zinc methacrylate in situ graft polymerization / EPDM nanocomposite. The optimal loading of ceramic nanopowder was determined based on the results of nanocomposites’ mechanical properties, oil resistance, wear resistance and anti-aging properties. The relationship between structure and properties of rubber ceramic nanocomposite was studied.7. Nano-silicon nitride modified with tercopolymer MAA-BA-AN / NBR nanocomposite is used to produce oil seal of automobile shock absorber; nano-silicon nitride modified with nano-zinc methacrylate in situ graft polymerization / EPDM nanocomposite is used to produce wear-resistant hose, nano-aluminum nitride modified with tercopolymer MMA-BA-VTES / NR/SBR nanocomposite is used to produce rubber stopper. The results of life test showed that these three products all reached the international advanced level.To sum up, the ceramic nanopowder（nano-silicon nitride and nano-aluminum nitride ） were applied to the preparation of rubber nanocomposites creatively. Novel macromolecular coupling agents for ceramic nanopowder were designed and synthesized according to different rubber nanocomposite systems. The uniform dispersion of nanopowders in the rubber matrix was realized successfully.The results confirmed that nano-silicon nitride and nano-aluminum nitride can not only enhance the strength and toughness of the rubber, but also improve other properties, such as oil-resistance, wear-resistance properties. Moreover, a thermal fogging nanopowder’s surface modification equipment, intermittent surface modification machine was designed and fabricated for the first time. All these works above explore a successful road for breakthrough the technological bottlenecks of nanoparticles’ dispersion in rubber.更多还原