Mechanical and tribological behavior of PTFE–polyoxadiazole fiber composites. Effect of filler treatment

Effect of RF plasma treatment of polyoxadiazole (POD) fibers in the medium of tetrafluoroethylene on structure, mechanical and tribological behavior of PTFE–POD fiber composite is studied. It is found that fiber treatment raises the composite density, heat resistance, mechanical strength and improves its tribological behavior. The tensile strength of the 10%-filled composite increases by more than 20% and elongation at break by ∼50% compared to the composite filled with the original fibers. Based on the results of IR-spectroscopy, DMA and SEM it is concluded that filler treatment produces a fluoroorganic coating with good wettability by the matrix polymer which reduces the void content and raises adhesion between the matrix and the fibers. This creates conditions for the stress transfer between the components producing the macroscopic changes in the composite properties.Changes in tribological behavior include an increase in both the load-bearing capacity and the friction coefficient compared to the original composite. Some improvement in the wear rate is observed at high specific loads.

► Interface modification in PTFE composites.
► RF plasma in TFE deposits a thin fluoroorganic polymer layer on POD fibers.
► The coating improves wetting of the fiber with PTFE melt and raises the fiber–matrix adhesion.
► Improved fiber–matrix adhesion raises the composite resistance to shear stresses at friction hence the friction coefficient.
► Enhanced toughness and heat resistance raise the loading capacity of the composite.
► Improved fiber–matrix adhesion prevents the fibers pull-out and reduces the wear rate at high pressures.