The influence of silane treatment on nylon 6/nano-SiO2 in situ polymerization

Silane treatment has been applied to the preparation of nylon 6/nano-SiO2 composites through in situ polymerization. The influence of such treatment on the reactivity of silica, polymerization of nylon 6, and the mechanical properties of the achieved composites has been studied. Fourier transform infrared (FTIR) spectroscopy and thermal gravimetric analysis (TGA) of silicas isolated from the composites have shown that the conversion of surface silanol groups to amino and epoxy groups did not cause a significant change in the reactivity of silica and that the percentage of silica surface grafting was around 15% for all treated and untreated silicas. End group analysis has shown that the presence of silica (pretreated or not) in the composite system resulted in the decrease of the average molecular weight of the polymer matrix. However, dynamic mechanical analysis and mechanical tests revealed that treating silica with silane improved the strength and toughness of the composite materials, while untreated silica improved their strength at the expense of toughness. This can be attributed to the existence of the flexible interlayer introduced by silane treatment. (C) 2002 John Wiley Sons, Inc.