Friction and wear properties of poly(methyl methacrylate)–hydroxyapatite hybrid coating on UHMWPE substrates

Poly(methyl methacrylate)–hydroxyapatite (PMMA/HA) composite has been successfully prepared for its application as coating on ultra high molecular weight polyethylene (UHMWPE). The hybrid coating was prepared by mixing PMMA obtained from methyl methacrylate (MMA) polymerization and medical grade hydroxyapatite (HA). FTIR technique was used to study the PMMA synthesis and hybrid composite coating. For comparative studies, pure PMMA coatings were also prepared in order to determine the influence of HA incorporation into PMMA matrix. The coating thickness was determined using image analysis software and increased from 32.61 μm to 34.01 μm when HA was added. The surface morphology of the coatings was characterized by Scanning Electron Microscopy (SEM). The wear tests for PMMA/HA and PMMA coatings on UHMWPE were carried out on a pin-on-disk tribometer in dry conditions with normal loads ranging from 2 to 10 N. The wear performance of PMMA coatings was improved by HA additions, obtaining lower friction coefficients and volume loss for PMMA/HA coatings than the corresponding values for PMMA coating under 10 N load.