Scratch and normal hardness characteristics of polyamide 6/nano-clay composite

This paper investigates the scratch and normal hardness characteristics of polyamide 6/nano-clay composite. It is found that the weight percentage (wt%) of nano-clay greatly affects the scratch properties of the composite because of the intercalated structure of the nano-clay in the composite for higher clay loading. The scratch hardness, computed using the scratch width data, decreases while the scratch force increases as the wt% of nano-clay particles added into the composite increases. On the other hand, normal hardness increases and so do the yield strength and the elastic modulus when the percentage of nano-clay is increased in the composite. The SEM images show that the width of the scratch groove increases as the weight percentage of nano-clay in composite increases. However, the depth of the scratch groove indicates the opposite trend. Such contrasting behavior between the scratch hardness and other mechanical properties is explained based on the microscopic image study and the change in the nature of this nano-composite with increasing wt% of the nano-clay. Finally, important sources of error in the measurement of scratch hardness of these nano-composites are also highlighted.