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

Abstract

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.