Strain Rate Effect on Mechanical Behaviors of Nylon 6–Clay Nanocomposites

This study aims to investigate strain rate effect on the mechanical behaviors of nylon 6–clay nanocomposites. Both dry and wet nylon 6–clay nanocomposites are examined in this study. To determine the strain rate effect, the nylon 6 nanocomposites with 5 wt% loading of the organoclay are tested in compression at different strain rates. For strain rates less than 1/s, the experiments are conducted using a hydraulic MTS machine. However, the high strain rate tests are performed using a split Hopkinson pressure bar (SHPB). To establish reliable dynamic stress and strain curves for the nanocomposites, a pulse-shaper technology is employed in the SHPB tests. Experimental observations reveal that for dry nanocomposites, the linear portions of the stress and strain curves are not affected substantially by the strain rates, but the yielding stresses increase with the increment of the strain rates. On the other hand, for the wet nanocomposites, the stress and strain curves are almost nonlinear demonstrating significant stiffening behaviors as the strain rates increase. This stiffening behavior is continuous until the stress and strain curves are almost linear at the strain rate of 500/s. Comparison of nylon 6–clay nanocomposites and unfilled nylon 6 indicates that the supplement of 5 wt% organoclay in the dry nylon 6 can enhance the Young's modulus to 32% within the tested strain rate ranges. Moreover, for the wet nylon reinforced with organoclay, the increment of Young's modulus can be achieved up to 43%.