A Polytetrafluoroethylene@Polyacrylonitrile core-shell composite with high tribological performance

Abstract

As a lubricating additive, polytetrafluoroethylene (PTFE) exhibited poor wear resistance, high wear rate and weak adhesion strength, which restricted its application in the area of lubrication and wear protection. In this paper, we prepared a PTFE-based core-shell composite (PTFE@PAN) composed of PTFE core and polyacrylonitrile (PAN) shell through an emulsion polymerization method. The PTFE core with diameter of about 80–100 nm was wrapped by the PAN shell with the thickness of about 50–60 nm. The PTFE@PAN core-shell composite present better dispersion stability in lubricating oil (poly-α-olefin 6, PAO6) than PTFE. Additionally, the PTFE@PAN composite dispersed in PAO6 exhibited significantly reduction in friction coefficient and wear scar width up to 50 % and 25 % compared to PTFE, respectively. Meanwhile, the wear volume of PTFE@PAN composite under a load of 200 N was 4.855 × 104 μm3, was merely one twenty-seventh of that of PTFE (130.6 × 104 μm3). In comparison to conventional oil lubricants, this enhanced tribological properties of PTFE@PAN composite were conducive to a homogeneous transfer film composed of the dual-phase hard polymer (PAN) and soft PTFE polymer (PTFE). Compared with PTFE, the lower surface hardness and better flexibility of PAN shell led to deformation and gap filling with the entanglement and motion of the molecular chains, which could reduce the scratches and decline the abrasive wear of the rubbing surface significantly in the course of the friction process on a rough surface under the high load. That results also suggested that the PTFE@PAN core-shell composite will be a potential lubricating and wear-resistant additive.