Mechanical and Tribological Studies of SU-8 Composites Filled With UHMWPE and Gum Acacia Under Dry and Bovine Serum Albumin Lubricated Conditions

Abstract

Abstract SU-8 polymer was mixed with ultrahigh-molecular weight polyethylene (UHMWPE) particles in various weight percentages (wt%) to make composites. Uniform distribution of filler material was confirmed by optical microscopy imaging. Cross-sectional scanning electron microscopy (SEM) analysis showed the formation of fibrillar structure of UHMWPE which helped bind UHMWPE particles with SU-8 matrix. Gum acacia made a coating on the UHMWPE particles and helped in binding with the matrix. The compressive Young’s modulus and strength of the composites were found to decrease with UHMWPE filler addition. The composites were tested in ball-on-disk tribometer using 12 mm diameter stainless steel (grade 304) ball under a normal load of 20 N and sliding speed of 32 mm/s. SU-8 with 25 wt% of UHMWPE showed coefficient of friction of 0.1 and specific wear-rate of 6.27 × 10−5 mm3/Nm which were 52% and 61%, respectively, lower in comparison with those of bulk UHMWPE tested in aqueous solution of bovine serum albumin (BSA). Adding 10 wt% of gum acacia to the SU-8/UHMWPE composite had beneficial effects on the wear-rate as the specific wear-rate of this hybrid composite further dropped to 4.6 × 10−5 mm3/Nm which was 71% lower than that of bulk UHMWPE.