Reinforcement of nylon-6 filaments with SiO2 nanoparticles and comparison of Young's modulus with theoretical bounds

Spherical silica nanoparticles were infused into nylon-6 and drawn into filaments through a melt-extrusion process. The idea was to improve the strength and stiffness of the resulting filaments by utilizing the interactions between the nanoparticles and the polymer. The focus was to increase the fracture strain of the filaments, as this had not been possible earlier with the infusion of carbon nanotubes. It has been observed that with the infusion of silica nanoparticles, the strength and Young's modulus of the nylon filament can be enhanced in the 28 to 36% range without any loss of fracture strain. The source of this improvement has been traced to the formation of stronger amide and carbonyl bonds, nucleated by the presence of SiO2 nanoparticles during polymerization. Moreover, calculations based on basic theories of inclusions show that the Young's modulus of the nanophased filament is within 5 % of the upper bound predicted by the micromechanical theory.