The present study investigates the effect of SiO 2 nanoparticle on the thermal and mechanical properties of nylon-6. Firstly, nanoparticles with 0, 1, and 2 wt.% loading were dry-mixed with nylon-6 by mechanical means and extruded into filaments using a single screw extruder. Then, tensile tests were performed on the single filament at the strain rate range of 0.02-2 min -1 . Experimental results show that both neat and nanophased nylon-6 were strain rate strengthening materials. The tensile modulus, yield strength, and ultimate tensile strength (UTS) all increased with increasing strain rate. Experimental results also show that infusing nanoparticles into nylon-6 can increase tensile modulus, yield strength, hardening modulus, and UTS. Forty-five percent enhancement in tensile modulus and 26% enhancement in UTS were observed in the 2 wt.% system as compared with neat nylon-6. At the same time, thermal properties of neat and nanophased nylon-6 were characterized by TGA and DSC. TGA thermograms have shown that the nanoparticle infused systems are more thermally stable. DSC studies also have indicated that there is a moderate increase in T g without a distinct shift in the melting endotherm for the nanophased systems. At last, based on the tensile test results, a nonlinear constitutive equation was developed to describe strain rate sensitive behavior of neat and nanophased nylon-6.