Polyphenylene sulfide (PPS) was filled with glass fiber (GF), aramid fiber (AF), and solid lubricants to improve the mechanical properties and wear resistance. The addition of GF effectively enhanced the tensile strength, flexural modulus, and impact ...
Polyphenylene sulfide (PPS) was filled with glass fiber (GF), aramid fiber (AF), and solid lubricants to improve the mechanical properties and wear resistance. The addition of GF effectively enhanced the tensile strength, flexural modulus, and impact strength of PPS, while solid lubricants such as polytetrafluoroethylene (PTFE), molybdenum disulfide (MoS<sub>2</sub>), and tungsten disulfide (WS<sub>2</sub>) lowered the friction coefficients of the composites to below 0.3. The ball nut and motor pulley of the electric power steering (EPS) were manufactured using the PPS composites, and feasibility was ascertained thereafter by conducting the durability test. The composites filled with GF and AF showed high mechanical strength, but slip occurred at the interface between the pulley and belt while testing above 50°C. When small amounts of lubricants were added, the slip was no longer detected because of the suppression of friction heat. It is realized that the low friction as well as high mechanical properties is important to ensure the reliability of plastic pulleys.