【作者】 王元霞；

【导师】 吴友平；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2011， 博士

【摘要】 近年来,人们对汽车安全、舒适、节能的要求逐年提高,相应的轮胎要求具有优异的抗湿滑性能、耐磨性能和低滚动阻力特性,这三项性能被人们称为“魔鬼三角”。新的欧洲法规标签将在2012年强制执行,主要内容是针对轮胎胎面的三大基本性能：滚动阻力、抗湿滑和噪声作为乘用车胎替换胎的硬性指标提出了限制。抗湿滑性能作为强制要求的性能之一,可见其是轮胎胎面胶最重要的性能之一,因此对其机理的研究是极其必要的。对于抗湿滑性能的机理,近二十年的关注越来越多,但同时又是充满挑战的,因为迄今没有得到系统的研究。到目前为止,还局限在用0℃的tanδ来表征抗湿滑性能,实际上当以白炭黑作为主要填料的绿色轮胎工业化之后,动态粘弹性能已经不能用来作为衡量抗湿滑性能的唯一指标,这对指导高性能轮胎胎面的配方设计是不利的。因此,研究动态粘弹性能对抗湿滑性能的贡献和不同填料填充胶的抗湿滑性能的关键影响因素和机理是本论文致力研究的方向。论文的第一部分,主要用LAT-100磨耗实验机测定了炭黑和白炭黑补强溶聚丁苯(SSBR)原位改性胶料的抗湿滑性能,用动态热分析仪(DMA)测定了胶料的动态粘弹性能,并分析了抗湿滑性能的影响因素。结果表明,在一定的温度和速度范围内,白炭黑SSBR胎面胶抗湿滑性能优于炭黑胎面胶；仅采用动态粘弹性能描述胶料的抗湿滑能是不全面的,抗湿滑性能受温度、速度和胶料硬度等的共同影响,随着温度的升高而降低,随着速度的增大呈现先增大后减小的趋势,这是润滑作用和动态粘弹性能等共同作用的结果。根据本章的结论,有助于指导抗湿滑性能影响的外因,并对本论文后几章研究具有指导意义。论文的第二部分,研究了动态粘弹性能对抗湿滑性能的影响。首先用DMA在拉伸和剪切两种模式下分别测定了0℃的tanδ随应变(0.7%-10%)的变化,在不同粒径炭黑补强体系中确定动态粘弹性参数tanδ表征抗湿滑性能的最佳条件,然后在炭黑和白炭黑补强不同丁苯胶体系中研究动态粘弹性能对抗湿滑的贡献。实验结果表明,对于相同硬度的不同粒径炭黑填充的SSBR/BR胶料,0℃的tanδ与抗湿滑性能的相关性系数高达0.98,此相关性系数下的tanδ的应变范围在拉伸模式下为4%-7%,在剪切模式下为0.7%-10%。因此接下来采用4%拉伸形变下的tanδ来表征动态粘弹性能与抗湿滑性能的相关性。对于炭黑和白炭黑填充不同的丁苯胶体系,炭黑和白炭黑胶料的tanδ分别与抗湿滑性能有很好的相关性,却没有统一的好的相关性。然而,对于未预磨的炭黑和白炭黑填充不同丁苯胶体系,可以得到统一的较好的相关性,此时胶料的抗湿滑性能可以直接用0-C的tanδ表征。以上充分说明了动态粘弹性能可用来对比同种填料补强炭胶料的抗湿滑性能,同时发现尽管炭黑胶料O℃的tanδ较高,所有白炭黑胶料的抗湿滑性能均优于炭黑胶料,故填料不同时,动态粘弹性能不再是抗湿滑性能的唯一决定因素,表面对抗湿滑性能的影响也需要考虑。炭黑和白炭黑粉末的纳米压痕硬度测试进一步说明了硬粒子的存在可能是白炭黑胶料抗湿滑性能优越的最重要的原因。根据本章的结论,有助于指导分析动态粘弹性能对抗湿滑性的贡献,同时引导我们去思考炭黑和白炭黑补强(不同种类填料补强)胶料抗湿滑性能差别的原因。论文的第三部分,探索了炭黑和白炭黑等不同种类填料补强胶料的抗湿滑性能机理。为了研究其机理我们进行了表面的表征,用白光干涉仪测定了胶料表面预磨后的表面粗糙度和三维表面形貌,用划痕实验对比了胶料的微观硬度。结果表明,在毛玻璃面和光滑玻璃面上白炭黑胶料的抗湿滑性能均优于炭黑胶料,但是动态粘弹性能不是白炭黑胶料抗湿滑性能优越的主要原因。进一步测定了胶料的表面粗糙度发现,胶料大的表面粗糙度有助于抗湿滑性能的改善,这可能是白炭黑填充胶料抗湿滑性能优于炭黑填充胶料的主要原因之一,XPS表面分析表明,白炭黑摩擦后表面的白炭黑粒子出现了脱落,无法证明摩擦后白炭黑粒子露在外面起到刺破水膜的作用；进而设计用胶料来摩擦玻璃的划痕实验进一步说明了白炭黑胶料的微观硬度远远高于炭黑胶料的微观硬度,这可能是白炭黑胶料抗湿滑性能优于炭黑胶料的又一重要原因。为了验证硬粒子对抗湿滑性能的改善作用,用金刚石部分等量代替炭黑和白炭黑补强胶料,抗湿滑性能的数据表明,加入金刚石之后,胶料的抗湿滑性能大幅度改善,进一步证明了硬粒子刺破水膜、改善抗湿滑这一结论的正确性,从而成功解决了白炭黑抗湿滑性能优越的原因这一难题——粗糙胶料表面和高的微观硬度对抗湿滑性能的改善作用。通过对比不同水膜厚度下炭黑、白炭黑、纳米金刚石胶料的抗湿滑性能,进一步验证了粗糙胶料表面和高的微观硬度在厚水膜时(约为50μm-1mm)对抗湿滑性能的改善作用。这对不同种类填料补强橡胶的抗湿滑性能机理研究和高抗湿滑性能轮胎胎面配方设计提供了指导。更多还原

【Abstract】 In the last decades, with the demand of energy conservation and emission reduction in our country and the increased requirements of security, energy-saving, and comfort for cares, good wet-skid resistance (WSR), abrasion resistance and low rolling resistance becomes the essential desire for high-performance tires, which are often called "magic triangle" in the tire industry. The new European label, accroding to three basic properties of tire tread, including the rolling resistance, WSR and voice, will be carried out in 2012. Therefore, the study on the mechanism of WSR is one of the research focuses and of significant importance. In the rencent twenty yeaars, the study on WSR gardually increased but without producing a systematial theory. Since the’green’tire was commercialized, it was found that besides the low rolling resistance, this tire featured better WSR. The viscoelasticity could no longer explain the better WSR of silica filled composites, which is disadvantages to the design of tire tread with high WSR. It becomes a changlling topic. Therefore, it is essential to study the contribution of viscoelasticity to WSR for filled rubber composites and the influence of other factors to WSR, which is the main research direction of this thesis.In the first part, we mainly studied the WSR of carbon black (CB)- and silica-filled SSBR (Solution styrene-butadiene rubber) composites measured with LAT-100 abrader and analyzed the influening factors. A dynamic mechanical thermal analyzer was used to obtain the visoelasticity of the composites. The results showed that the silica-filled composites exhibited better WSR than CB-filled composites under the measuring conditions. It was not sufficient to represent WSR just using viscoelasticity. The temperature, velocity and the hardness of the composites also have effect on WSR. The WSR increases with the decreasing temperature and the increasing velocity, which was caused by the water lubrication effect and viscoelasticity. The conclusions of this part are in favor of choosing the influencing factors of WSR and have significance on the subsequent parts.In the second part, we mainly revisited the role of viscoelasticity in WSR of rubber composites by comparing the effects of CB and silica on WSR. The WSR on wet ground glass was obtained with a portable British Pendulum Skid Tester (BPST). Under shear and tensile modes, tanδof the composites was measured at 0℃in a wide range of strains (0.7%-10%) via a dynamic mechanical analyzer. For different sizes of CB-filled composites, a high correlation coefficient (R2=0.98) between WSR and tan 8 under both shear (0.7%-10%) and tensile (4%-7%) modes was obtained. Tanδat tensile strain 4% was thus adopted as a parameter to characterize viscoelasticity. Good correlations at tensile strain of 4% was also found for CB- and silica-filled SBR composites with rough surface, while a good correlation was also observed for rubber composites with smooth surface regardless the type of filler. The higher WSRs of silica-filled composites over those filled with CB were mainly due to the higher nanohardness of silica. All these results demonstrate that WSR can be predicted from viscoelasticity for composites with similar surface roughness and micro-hardness. Basing on this conclusion, it is helpful to analyze the contribution of viscoelasticity to WSR. Besides, it guides us to explore the mechanism of WSR for different fillers-filled system. Therefore, the conclusions of this part are in favor of choosing the influencing factors of WSR and have significance on the subsequent parts.In the third part, we mainly studied the wet skid resistance (WSR) of SSBR/BR (Butadiene rubber) composites filled with carbon black, silica, and nano-diamond partly replacing carbon black or silica, respectively, with BPST. A 3D scanning white-light interfering profilometer was used and the scratch test performed to characterize surface roughness and micro-roughness, respectively, of the composites. WSR of the silica filled composite was better than that of the carbon black filled one, and further enhancement of WSR was obtained by replacing silica with nano-diamond. Tanδof the composites at 0℃,10 Hz, and tensile strain of 5% did not show good correlation with WSR. The surface roughness of the composites had effects on WSR. The scratch test was designed to compare the micro-hardness of the composites surface, which indicated that the higher the hardness of the filler in the composite, the higher the micro-hardness and the better the WSR. Therefore, the surface micro-hardness of the composites is an important factor affecting WSR, besides viscoelasticity and surface roughness. Besides, we studied the influence of water film thickness for WSR for the composites filled with carbon black, silica, and nano-diamond. It further indicated that the effect of stiff particles is of significant importance for improving WSR when the water film is thick (50μm-1mm).更多还原