有机蒙脱土对端羧基聚丁二烯凝胶流变行为的影响

EFFECT OF ORGANOCLAY ON THE RHEOLOGICAL BEHAVIOR OF CARBOXYL-TERMINATED POLYBUTADIENE GELS

在恒定剪切速率下,利用旋转流变仪研究端羧基聚丁二烯/蒙脱土纳米复合凝胶的流变行为,同时利用X-射线衍射(XRD)和透射电镜(TEM)等表征手段研究其微观结构.研究结果表明,该体系在26～116℃的升-降温过程中,观察到不可逆转变和可逆转变两种流变行为,其中不可逆转变流变行为归因于蒙脱土片层的剥离过程,而可逆转变流变行为归因于已剥离蒙脱土片层的取向-去取向过程.通过对此类纳米复合凝胶流变行为的测试,实现蒙脱土片层在端羧基聚丁二烯基体中分散过程的原位观测,并总结出影响该复合凝胶流变行为的三大因素:温度效应、剪切诱导取向效应和聚合物与蒙脱土之间的相互作用,最后提出一个机理来理解有机蒙脱土对端羧基聚丁二烯凝胶流变行为的影响,以及液体橡胶/有机蒙脱土纳米复合凝胶的独特流变行为与微观结构之间的关系.

The unique rheological behavior of carboxyl-terminated polybutadiene（CTPB）/organoclay nanocomposite gels was studied under steady shear on a HAAKE RheoStress 600 instrument.The microstructure of nanocomposite gels was characterized by X-ray diffraction（XRD） and transmission electron microscopy（TEM）.The experimental results show that both irreversible and reversible viscosity transitions were observed in the temperature range from 26℃ to 116℃ in steady shear experiments on as-prepared samples.The irreversible viscosity transition is attributed to the exfoliation of the clay sheets,and the reversible viscosity transition can be understood as a shear-induced orientation-disorientation transition of the clay sheets.Moreover,the in-situ dispersion process of organoclay in CTPB matrix was observed by rheological experiments,and three important factors that significantly affected the rheological behavior of CTPB/organoclay nanocomposite gels in the steady shear measurement were studied：the temperature effect,the shear-induced orientation effect and temperature-sensitive polymer-clay interaction.Finally,a possible mechanism was suggested on the basis of the clay exfoliation and orientation-disorientation transition,and the mechanism was used to explain the effect of organoclay on the rheological behavior of CTPB gels and the relationship between the observed unique rheological behavior and the microstructure of nanocomposite gels.