NYLON 6/TiO2 COMPOSITES BY IN SITU ANIONIC RING-OPENING POLYMERIZATION OF epsilon-CAPROLACTAM: SYNTHESIS, CHARACTERIZATION, AND PROPERTIES

Two series of nylon 6/TiO2 composites were obtained via anionic ring opening polymerization of epsilon-caprolactam in the presence of untreated and surface-treated TiO2 with 3-aminopropyl-triethoxysilane (APTEOS) as coupling agent by the rotational molding technique. The polymerization process was carried out using a system initiator/activator based on sodium dicaprolactamato-bis(2-methoxyethoxo) aluminate and N,N'-[methylene-di(4,4'-phenyle-phenylene)bis-carbamoyl]bis-epsilon-caprolactam. All tests were performed at the initial polymerization temperature of 160 degrees +/- 2 degrees C. The influence of both untreated and treated TiO2 particle concentration on the degree of conversion (DC), intrinsic viscosity [eta], weight-average molecular weight ((M) over bar (w)), and water absorption of pure nylon 6 and its composite materials was investigated in the range of 0.0 to 8.0 wt.% TiO2. The thermal behavior and crystalline structures of pure nylon 6 and its composites have been studied in correlation with filler concentration by differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), and room temperature wide-angle X-ray diffraction (WAXD). The mechanical characteristics, including tensile and flexural properties, elongation at break, and notched Izod impact strength, of nylon 6 and its composites as a function of TiO2 filler content were investigated for all samples. Experimental results revealed that the unmodified and surface-modified TiO2 as fillers had distinct influence on the degree of conversion, weight-average molecular weight, crystallization behavior, thermal stability, mechanical properties, and water absorption of nylon 6 matrix.