SSBR/SiO_2混炼胶的动态黏弹行为

DYNAMIC RHEOLOGICAL BEHAVIOR OF SSBR/SiO_2 COMPOUNDS

研究了白炭黑(SiO2)填充溶液聚合丁苯橡胶(SSBR)的动态流变行为,考察了时间-浓度叠加(time-concentration superposition,TCS)原理在粒子填充橡胶中的应用,获得以未填充SSBR为基准的流变叠加曲线.流变叠加曲线在低频下呈现模量平台,复数黏度呈现剪切变稀行为,而损耗因子tanδ在特定频率下出现峰值.基于刚性粒子所导致的应变放大效应以及SiO2粒子间SSBR分子的受限运动,探讨了TCS模量平移因子AG与频率平移因子Aω随SiO2体积分数φ的变化.AG与Aω均为φ的标度函数,但AG～φ关系不符合粒子聚集体团聚(cluster-cluster aggregation,CCA)模型.讨论了偶联剂3-辛酰基硫代-1-丙基三乙氧基硅烷(NXT)对动态流变行为的影响.NXT不影响性叠加曲线的低频平台模量与剪切变稀幂律指数.然而,与不含偶联剂的混炼胶相比,NXT造成SSBR特征弛豫时间缩短,稠度与A增大.

Dynamic rheological behaviors of silica white （SiO2） filled solution-polymerized styrene-butadiene rubber （SSBR） compounds were investigated, and application of the time-concentration superposition （TCS） principle to this system was verified. Master curves were obtained by shifting the frequency sweep rheological data of the filled compounds with respect to the unfilled SSBR. The master curves disclosed the existence of modulus plateaus in the low frequency region while the complex viscosity exhibited marked shear-thinning. The master tanδ curves displayed maximum at a characteristic frequency that decreased with increasing filler volume fraction φ. The modulus and the frequency shift factors, AG and Aw, were introduced into the TCS principle on the basis of strain amplification effect due to the presence of rigid undeformable SiO2 particles as well as the constrained molecular particles. Scaling relations were revealed to AG and Aw as a function of φ. However, the motion of SSBR among AG-φ relation did not follow the cluster-cluster aggregation （CCA） model that was usually suggested for particle suspensions or particle filled polymers. Influence of 3-octanoylthio-1-propyltriethoxysilane （NXT） as coupling agent to the dynamic rheological behaviors was also discussed. NXT did not influence the modulus plateaus and the shear-thinning index whereas it caused a reduction in characteristic relaxation time and marked increments in consistency and Ac in comparison with the NXT-free compounds.