Nylon 6/SiO2 nanocomposites synthesized by in situ anionic polymerization

摘要

In situ anionic polymerization of epsilon-caprolactam in the presence Of SiO2 and silanated SiO2 nanoparticles was promoted as a route for the synthesis of two series of nylon 6/SiO2 nanocomposites. The process was performed at 160 degrees C well below the melting temperature of the nylon 6 (T-m similar to 225 degrees C) and initiated/activated with sodium dicaprolactamato-bis(2-methoxyethoxo)aluminate/N,N'-[methylene-di(4,4'-phenylene)bis-carbamoyl]bis-epsilon-caprolactam system. The nanocomposites obtained exhibit higher onset decomposition temperatures than neat nylon 6 and a tendency of reduction of the polymer yields, degree of polymerization, water absorption and melting temperatures with silica content increasing. The crystallization temperature, T-c of the nanocomposites reaches a maximum value at 2.0 wt.% of the nanoparticles. The mechanical tests of nanocomposites revealed an increase in flexural modulus as a function of filler percentage and a decrease in notched impact strength by addition of the modified silica (over 4.0 wt.%) and unmodified silica. Furthermore, the flexural strength diminishes both the treated and untreated filler content is increased for concentration of > 4.0 wt.%.