A reactive polyamide 6 (PA6)/SiO2 masterbatch (MA) containing 20% (mass fraction) of nano-SiO2 was prepared readily. Furthermore, the as-prepared reactive MA was used as a filler to prepare PA6/SiO2 nanocomposites (RA). The structure of RA was analyzed by means of Fourier transform infrared spectrophotometry (FTIR), transmission electron microscopy (TEM), powder X-ray diffractometry (XRD), scanning electronic microscopy (SEM) and polarizing microscopy (POM). Thermal stability and crystallization behaviors of RA were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Findings indicated that the PA6 molecular chains were anchored on the surface of nano-SiO2 through chemical bonding between the surface amino groups of nano-SiO2 and ε-caprolactam monomer or prepolymer of PA6. As a result, a flexible interfacial layer was formed, thereby improving the compatibility of nano-SiO2 with PA6 matrix. Moreover, the enhancement effect of nano-SiO2 led to the improved mechanical properties of RA. Besides, due to the hindering effect of nano-SiO2 particles to the movement of PA6 molecular chains, the size of the PA6 spherocrystal was smaller, and its crystalline form was also affected. Furthermore, the molecular weight of the PA6 matrix tended to decrease gradually with increasing nano-SiO2 content.
PA6; nano-SiO2; masterbatch technique; in situ polymerization; composites
