Enhanced Mechanical and Tribological Properties of PMMA via Silane-Functionalized Graphene Oxide

Poly(methyl methacrylate) (PMMA) exhibits a high coefficient of friction, limiting its use in tribological applications. To address this, graphene oxide (GO), synthesized via the Hummers method, is functionalized with silane KH570 to enhance its compatibility and subsequently incorporated into PMMA through in situ bulk polymerization, resulting in PMMA/KH570-GO composites. The structural, morphological, and functional properties of the composites are characterized using x-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Mechanical and tribological behaviors are assessed through tensile and pin-on-disc tests. The results indicate that the addition of 0.06 wt% KH570-GO enhances tensile strength by 13.4%, achieving a value of 76.25 MPa, and significantly reduces the coefficient of friction from 0.7 to 0.25, compared to pure PMMA. Beyond this threshold, a higher KH570-GO loading of 0.20 wt% diminished the tensile strength to 59.23 MPa. The optimal content, in contrast, improved mechanical properties and promoted the development of a lubricating graphitic film during friction, which collectively contributed to a marked enhancement in tribological performance.