The Role of Organoclay on Microstructure Development and Rheological Properties of Poly(Butylene Terephtalate)/Epoxy/Organoclay Hybrid Systems

The main objective of the present work was to study the role of organoclay on the microstructure development and rheological properties of poly(butylene terephtalate)/ epoxy/organoclay (Cloisite® 30B) hybrid nanocomposites. The effects of feeding order and curing of the epoxy were also investigated. The hybrid nanocomposite samples were prepared by melt compounding in a laboratory internal mixer at a temperature of 240°C. The samples were prepared by three feeding routes; (1) simultaneous feeding, (2) PBT/organoclay based master batch feeding, and (3) epoxy/organoclay based master batch feeding. The XRD results evidenced a highly intercalated microstructure for all the samples. The linear viscoelastic results obtained for uncured samples, prepared by the first and second feeding routes, exhibited a pronounced low-frequency nonterminal behavior whose extent was found to be increased in the cured samples. These results suggested that the major part of the nanoclay tactoids and/or platelets were dispersed in the PBT matrix, with higher nanoclay concentration in the sample prepared by the second feeding route. However, the samples prepared through epoxy/organoclay based master batch did not exhibit an appreciable low-frequency solid body response. This suggests that the process of migration of the nanoclay tactoids and/or platelets from epoxy droplets to PBT matrix was the time consuming process due to the high aspect ratio of the nanoclay and the high viscosity of the PBT matrix. From linear and nonlinear viscoelastic measurements, it could be deduced that the curing process does not play an important role in determining the extent of intercalation and dispersion of the nanoclay, but it can enhance the interfacial interaction between the two phases in the nanocomposite.