Structure and thermal behaviour of nylon 6 nanocomposites

In this article, nylon 6/clay nanocomposites with 5 wt 9% clay (NCN5) were prepared by a twin screw extruder. The effects of annealing including solid-state annealing (170 and 190 degrees C) and melt-state annealing (240 degrees C) on the polymorphic behavior and thermal property of NCN5 and nylon 6 have been comparatively studied as a function of annealing time using modified differential scanning calorimetry (MDSC) and wide-angle X-ray diffraction. It was demonstrated that NCN5 and nylon 6 exhibit a similar polymorphic behavior when they were annealed at 190 degrees C for different time durations. As the annealing temperature was elevated to 240 degrees C, significant differences in thermal behavior and polymorphism between NCN5 and nylon 6 could be found. For example, the a crystal became the absolutely dominating crystalline phase for NCN5 sample independent on the annealing durations, whereas the formation of gamma crystal is greatly enhanced in neat nylon 6 with increasing annealing time. Moreover, a small endothermic peak is observed around 180 degrees C in both nylon 6 and NCN5 samples annealed at 170 and 190 degrees C, which might be related to the melting of microcrystals formed in the amorphous regions during annealing. (c) 2006 Wiley Periodicals, Inc.