“…The lubricant fillers include the familiar PTFE, graphite, MoS 2 , etc (Lu and Friedrich, 1995;Qiao et al, 2007;Khare et al, 2015;Zalaznik et al, 2016;Chen et al, 2020;Li et al, 2022b). Gu et al found that the wear surface of polymethyl methacrylate (PMMA) was uneven with many torn flakes and surface bumps, and the COF curve fluctuated in a wide range, while the wear surface of PTFE/PMMA composites filled with PTFE was relatively smooth with only slight scratches and a smoother COF curve, indicating that the friction process of PMMAbased composites is more stable by filling with PTFE.…”