Effect of Various Polyimide (PI) Ratios on the Wear Resistance and Mechanical Properties of PI/Polytetrafluoroethylene (PTFE) Blends

Filling polytetrafluoroethylene (PTFE) with polyimide (PI) could effectively improve the properties of PTFE-based blends. In our research described in this article, five PI/PTFE-blend specimens with various conditions were prepared by a cold-pressing, sintering method using various ratios of PI. The PI/PTFE blends were tested for mechanical and wear resistance properties. The surface morphology of the blends was observed using an ultra-field electron microscope. The maximum tensile strength was 32.18 MPa at a PI ratio of 12.5 wt.%. The variation of the PI ratio caused changes in the dispersion of the filler in the matrix, which affected the mechanical properties of the blends. When the PI content was 15 wt.%, the lowest volumetric wear degree of the PI/PTFE blends occurred, 7.8327 × 10−7 mm3/Nm. When the ratio of PI was too high, the PI filler was more likely to be detached from the PTFE matrix in a large area during the friction experiments. This would lead to the blends being more prone to generating abrasive debris during friction, and the buildup and sliding of these abrasive debris on the friction interfaces increased the volumetric wear rate and the coefficient of friction of the blends.