Study of the Micropore Structure and Tribological Properties of PTFE-Modified Porous Polyimide

To address the challenges of regulating micropore properties and improving the tribological performance of porous polyimide (PPI), PPI/PTFE composites were fabricated via cold pressing–sintering. The effects of PTFE content on porosity, oil absorption/retention, and tribological behavior were systematically studied. Results show that PTFE addition significantly reduced porosity—by 1.8% to 7.9% as PTFE increased from 5 wt% to 30 wt%—while markedly enhancing dry friction performance. The friction coefficient decreased from 0.22 to 0.06 with 30 wt% PTFE, with optimal performance at 20 wt% (friction coefficient: 0.068; wear rate: 1.5 × 10−6 mm3/N·m). Oil-impregnated samples exhibited further improved tribological properties (friction coefficient ≈ 0.047), attributed to lubricant release forming a protective oil film. Although PTFE promotes lubricant release, it increases wear at higher contents. A PTFE content of 0–10% balances porosity control and tribological performance.