Friction and wear of monolithic and glass-fiber reinforced PA66 in humid conditions

Effect of water absorption on friction and wear of polyamides, namely monolithic polyamide 66 (PA66) and PA66 composite with 30 wt% of short glass fibers, was investigated using a block-on-ring-type tribotester. Monolithic PA66 showed high wear rates after water absorption because of softening by the absorbed water molecules and increased interfacial adhesion on the steel counter surface. Degraded wear characteristics of monolithic PA66 by chain scission of the amide functional group by water molecules were substantially improved by short glass-fiber reinforcement. The improved friction and wear characteristics were attributed to contact plateaus produced during sliding, which were held by condensed glass fibers, suggesting possible applications of PA66 in a humid environment by reinforcing it with short glass fibers.