Influence of sliding velocity on microscratch response of carbohydrate polymers by Berkovich indenter.

Microscratch tests were carried out on polyamide (PA) and polypropylene (PP) by Berkovich indenter to study influence of sliding velocity on microscratch response of carbohydrate polymers. Both penetration depth and residual depth decrease nonlinearly with the increase of sliding velocity. Elastic deformation is dominant in the total deformation during scratching of polymers. Both residual and contact scratch widths decrease nonlinearly with sliding velocity. The elastic recovery rate increases with sliding velocity. Both scratch hardness and lateral hardness increase nonlinearly with sliding velocity. Scratch hardness also increases nonlinearly with the increase of strain rate due to strain rate hardening effect. Scratch friction coefficient of PA decreases with increasing sliding velocities, and can be regarded to be constant under large sliding velocities. Nevertheless, scratch friction coefficient of PP increases with sliding velocity. Residual scratch grooves, scratch friction coefficient, and lateral force under different sliding velocities can be used to reveal the different friction mechanisms of PA and PP. • Microscratch responses of two carbohydrate polymers were investigated by Berkovich indenter. • Strain rate sensitivity was investigated by adjusting sliding velocity. • Friction mechanisms of two polymers were compared. • Effects of sliding velocity on scratch variables were quantified under different normal loads. • Friction coefficient, residual groove, and lateral force can be used to study friction mechanism. [ABSTRACT FROM AUTHOR]