【作者】 王雷；

【导师】 赵素合；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2010， 博士

【摘要】 近年来,随着国家节能减排战略目标的实施,汽车安全、舒适、节能的要求逐年提高,与其配套的轮胎要求具有优异的抗湿滑性能、耐磨性、低滚动阻力特性等,但这三项性能难以同时改善,往往其中的一项或两项性能改进的同时会引起另一项或两项性能的损失,人们常将这三项性能称为“魔鬼三角”。为平衡该三种性能,必须在橡胶的分子结构的设计改性以及填料补强结构上有新的突破。众所周知,橡胶分子间的内摩擦损耗和松弛特性是制约其低滚阻和高抗湿滑性能的主要因素,因此节能橡胶的分子结构设计及实施是研究的热点课题之一。在轮胎工业中,大量白炭黑用于补强胎面,收到了显著的节能和高抗湿滑效果,但带来的另一问题是易积蓄静电。因此,通过分子结构设计和纳米填料增强以及添加其他导电填料,来提高填料分散性及复合材料的抗静电性,并平衡轮胎的“魔鬼三角”性能的目标是本论文致力研究的方向。论文的第一部分,主要研究了五种胎面用丁苯橡胶／炭黑复合材料的结构-性能及防静电特性。结果表明,四种溶聚丁苯橡胶的力学性能和湿抓着性能与乳聚丁苯橡胶相近,但生热性和低滚动阻力特性明显优于乳聚丁苯橡胶；四种溶聚丁苯橡胶相比,星形SSBR的力学性能优异,内摩擦损失最低,抗湿滑性好且滚动阻力低,其次为SL552,2305和YL950,表明偶联结构的SSBR具有显著的节能特征。但YL950的门尼粘度低,加工性能优异,硫化时间短,且胶料的防静电性能优异。还研究了高分子量充油SSBR胶料的结构-性能及防静电性,充油SSBR表现出良好的炭黑分散性和较低的滚动阻力特性。对于50份炭黑填充上述丁苯胶料的电阻率均能满足防静电性要求,说明分子结构参数变化和端基改性技术对SSBR胶料的防静电性能影响不大。根据本章的结论,有助于选择新型胎面用丁苯橡胶,并对本论文后几章研究具有指导意义。论文的第二部分,研究了节能,高性能且防静电胎面用胶的配方。首先研究了炭黑及白炭黑填充SSBR胶料的防静电性和白炭黑填充胶料的加工工艺,发现50份炭黑可使胶料具有抗静电性和良好的力学性能,而SSBR/SiO2胶料则表现出绝缘特性。其次,分别研究了SiO2/CB不同并用比填充SSBR YL950和ESBR 1500复合材料的结构与性能关系及防静电特性。实验结果表明,在填充量为70phr的橡胶基体中,炭黑由约30nm的较透明的球状颗粒形成珠链状网络结构。该胶料的Payne效应高,动态损耗高,但具有优异的抗静电性能；SiO2粉体在橡胶中为黑色20-40nm的不规则颗粒,胶料表现出优异的湿抓着性能,低的内摩擦损耗,但静电积累量大。SiO2/CB并用填充SSBR复合材料的力学性能呈现“协同效应”,尤其当SiO2/CB并用比为20／50时,复合材料的物理机械性能、低生热性、磨耗性能、抗湿滑性和滚动阻力均达到较佳水平,且满足防静电性要求。而SiO2/CB(35／35)为复合材料防静电性的渝渗阈值,而当填料总量变化,SiO2/CB (1/1)填充SSBR胶料,由于粒子间距较远或纳米填料的分散性差,均未达到防静电要求。接着研究了导电炭黑部分取代炭黑和四针状氧化锌晶须填充SSBR/SiO2/CB复合材料的防静电性,力学性能及生热性等,得出导电炭黑用量增加,防静电性能提高,但力学性能降低,填料的分散性变差,且生热高的结果,对于SiO2/CB并用比为40／30时,满足防静电性的导电炭黑最小用量为3 phr；而防静电氧化锌晶须,虽然具有独特立体四针状显微结构,但在加工过程中,易折断,不利于导电网络的形成,而且填充补强效果差,所以在加工工艺上还有待改善。此外,硫化胶的不同停放时间对复合材料的电阻率的影响不大,高芳油加入对复合材料力学性能和生热性有所改善,但对防静电性能的不利。论文的第三部分,研究了端基改性SSBR的结构与性能及其与炭黑的相互作用。其一,从分子结构设计角度出发,在阴离子活性聚合反应末期加入大体积官能团,叔丁基二苯基氯硅烷进行封端改性,制备出分子链末端可以吸附炭黑,并起到钝化大分子链自由末端作用的溶聚丁苯橡胶,通过核磁技术证明了端基改性溶聚丁苯橡胶的反应结果,并根据核磁谱图中相关特征峰的峰面积计算了封端效率(即带有大体积官能团的大分子链末端数与总的分子链末端数之比)。大体积官能团封端后的胶料经过炭黑补强,填料-聚合物作用大大增强,填料分散性也显著提高,分子链自由末端明显减少,因此复合材料的力学性能和回弹性提高,生热和滞后损失明显降低,高抗湿滑和低滚动阻力等特性也得到明显的改善,并将其与星形溶聚丁苯橡胶和普通溶聚丁苯橡胶进行对比,由于大体积官能团可以钝化分子链末端(减少内摩擦损耗和增加在外立场中的取向度)和吸附炭黑的作用,其综合性能优异,适合作为节能型胎面胶料应用到轮胎工业中。其二,还研究了用对苯醌做模型化合物,来模拟Sn-C键向炭黑表面的键接反应机理,采用DSC, FTIR, GPC-UV联用等技术,追踪自合成的模型化合物-锡偶联聚丁二烯与对苯二醌的反应过程,并鉴定了反应产物,研究发现偶联型SSBR在空气和氮气气氛中分别于180和198℃出现化学键的断裂吸热峰,Sn-C键键能比C-C键弱,在热、力或化学催化作用下易断裂生成自由基,之后被醌基捕捉,形成端部带完整苯环结构的化合物。从而揭示了Sn偶联SSBR的Sn-C键向炭黑表面的键接转移机理以及Sn偶联SSBR内耗低的本质所在,为端基改性技术在SSBR中的应用提供了理论基础。更多还原

【Abstract】 Recently, with the demand of energy conservation and emission reduction in our country and the increased requirements of security, energy-saving, and comfort for cares, their high-performance tires should have good wet-skid resistance, abrasion resistance and low rolling resistance. However, The three performances are hard to be improved simultaneously, (i.e., one or two properties are improved whereas another two or one property will be decreased), which are often called "magic triangle" in the tire industry. Accordingly, it is a hard problem for the researchers all over the world to develop an ideal tread compound to balance the "magic-triangle" properties. It should have new breakthrough in molecular structure and reinforced structure of rubber. As is well-known to us, the internal friction losses among macromolecular chains and relaxation characteristics are the main factors. Therefore, the design of molecular structure of energy-saving rubber is one of research focuses. Besides, SiO2 is widely used in the tire tread compound for reinforcing function and the significant energy-saving effect and high wet-skid resistance are obtained. However, another problem comes, that is, it is easy to accumulate static. Therefore, how to get better filler dispersion and antistatic property and balance the "magic triangle" properties of the tire tread through molecular structure design, nano-filler reinforcement and adding other conductive fillers is the main research direction of this thesis.In the first part, we mainly studied the structure-property and antistatic characteristics of five kinds of tread compounds, SBR/CB composites. The results showed that the mechanical properties and wet-skid resistance of the four SSBR are similar with those of ESBR, however, the lower heat build-up and rolling resistance are superior to those of ESBR. By comparation of these four kinds of SSBR, the mechanical properties the star-shaped SSBR are excellent, its internal friction loss is the lowest, its wet-skid resistance is high and its rolling resistance is low, followed by SL552,2305 and YL950. Mooney viscosity of YL950 is low, its processing ability is better and vulcanization time is short, with excellent antistatic properties. It indicated that Sn-coupled SSBR have significant energy saving characteristics. In addition, we also studied the structure-property relationship and its antistatic characteristics of oil-extended SSBR with high molecular weight, which exhibited better CB dispersion and lower rolling resistance. The resistivity of all the researched SSBR composites with 50 phr pure CB could meet the antistatic requirements, therefore, the changes of molecular structure parameters and end-modification technologies have less effect on the antistatic property. The conclusions of this part are in favor of selecting novel tire tread compounds and have significance on the subsequent parts.In the second part, we mainly studied the formulations of energy-saving, high-performance and antistatic tread compounds. First of all, we investigated the antistatic characteristics of SSBR with pure CB or SiO2 and the technics of SSBR composites filled with SiO2. It was found that SSBR composites with 50 phr CB exhibited excellent antistatic and mechanical properties, however, the SSBR/SiO2 composites displayed insulation property. Secondly, we studied the structure-property and antistatic characteristics of SSBR YL950 and ESBR 1500 composites filled with different ratios of SiO2/CB. The experimental results showed that CB is 30 nm transparent and spherical particles and form bead-chain network structure. Its Payne effect and dynamic loss are high, and have excellent antistatic property; SiO2 powder exhibited 20-40 nm black and irregular particles, and SSBR/SiO2 composites displayed excellent wet-skid resistance, lower internal friction loss, however, larger static accumulation. SSBR/SiO2/CB composites presented "synergistic effect" effect, especially when the ratio of SiO2/CB is 20/50, the mechanical properties, lower heat build-up, wear resistance, wet-skid resistance and rolling resistance are well balanced, and the antistatic requirement could be met. SiO2/CB (35/35) is the percolation threshold of the composites for antistatic property. Furthermore, when the total amount of fillers is changed, with SiO2/CB in 1/1, the SSBR composites could not meet the antistatic requirements, because of the long distance of fillers or poorer dispersion of the nano-fillers. Then we investigated the CB and ZnO-W effect on the antistatic property, mechanical properties and heat build-up of the SSBR/SiO2/CB composites. It could be found that when the amount of conductive CB was rising, the antistatic property was improved, however, the mechanical properties were decreased, the filler dispersion was poorer and the heat build-up was higher. As for SiO2/CB (40/30), the least amount of the conductive CB is 3 phr in order to meet the antistatic requirement. Nevertheless, ZnO-W was easy to be broken during processing, which went against the formation of conductive networks and presented poor reinforcement. Therefore, the technics should be improved. Moreover, the different storage time of the vulcanizates have less effect on the antistatic property and high aromatic oil could improve the mechanical properties and lower heat generation, however, did harm to the antistatic property. In the third part, we studied the structure-property of end-modified SSBR and its interaction with CB. On one hand, SSBR with tert-Butylchlorodiphenylsilane (TBCSi, large-volume functional groups) at the two ends of macromolecular chains (T-SSBR) were prepared by anionic polymerization. The molecular structure parameters of T-SSBR and SSBR were characterized and the ratio of the amount of macromolecular chain ends connected with TBCSi to total macromolecular chain ends (i.e., end-capping efficiency) was calculated. The results showed that T-SSBR composites presented lower better CB dispersion than those of SSBR composites, which led to decrease in hardness, internal friction, dynamic compression heat built-up and permanent set of T-SSBR composites, significant increase in tensile strength, elongation at break, tear strength and resilience of T-SSBR composites, and excellent balance between wet-skid resistance and rolling resistance. All the above, owing to the end-capping of TBCSi, which could immobilize the free chain ends of T-SSBR (i.e., to reduce the friction loss of molecular chains and create a greater degree of orientation in the force field), and adsorb CB, the comprehensive performances of T-SSBR were better than those of SSBR, therefore the former was suitable for the tread of green tires. On the other hand, we used p-benzoquinone to simulate the transferring of Sn-C bond to CB surface and DSC, FTIR, GPC-UV and 1H NMR technologies were adopted to trace the reaction mechanism of star-shaped PB and p-benzoquinone. It could be found that Sn-C bond of Sn-coupled SSBR is more instable than C-C bond and easy to be broken in 180℃(air) and 198℃(nitrogen). The free radical was produced and caught by p-benzoquinone, and then the molecular chain with benzene-ring structure on the end was formed. Thus the transfer mechanism of Sn-C bond of Sn-coupled SSBR to CB surface and its internal loss essence were achieved. The theoretical principle for the application of end-modification SSBR could be provided.更多还原