Adding Aramid Fibers to Improve Tribological Characteristics of two Polymers

This paper presents the influence of the matrix on tribological properties of composites having 10% aramid fibers. Polyamide (Relamid) and PBT (Crastin) were used as matrix. The short aramid fibers (Teijin) were approximately 200...250 µm in length and 10 µm in diameter, with expended extremities due to manufacturing process. Tests were done on block-on-ring tribotester on a BRUKER-CETR®.UTM 2 system. The test parameters were: sliding speed (0.25, 0.50 and 0.75 m/s), the load (5, 10, 15 and 30 N) and the sliding distance of 5,000 m. There were analyzed the dependence of friction coefficient, temperature on the contact edge and wear of the polymeric materials. SEM images help identify wear mechanisms and pointed out the different behavior of the two matrixes. Adding aramid fibers into a matrix of either PA or PBT makes the resulting blends have better tribological characteristics: the wear is much lower, the friction coefficient slightly increases, but remaining in an acceptable range for actual applications as compared with the neat polymers. PBT + 10% wt aramid fibers had the lowest wear versus a slightly higher coefficient of friction as compared to that of PBT, for the tested regimes.