Thermomechanical and tribological properties of polyimide and polyethersulfone blends reinforced with expanded graphite particles at various elevated temperatures

Abstract

AbstractExpanded graphite (EG) particles were introduced into the polyimide (PI) and polyethersulfone (PES) blend to enhance the dynamic thermomechanical and tribological performances of this polymer composite at evaluated temperatures ranging from room temperature to 250°C. The influences of EG dosage, evaluated temperature and vertical loads on the high‐temperature tribological behaviors, worn surface morphologies and wear mechanisms of EG/PES/PI composites were analyzed. Experimental results suggest that tensile strength, dynamic storage modulus, glass transition temperature as well as thermal stability of EG/PES/PI composites are superior to those of the PES/PI blend and they are raised as the EG additions increase. Whether at room temperature or at the high temperature of 250°C, the EG/PES/PI composites display the better friction‐reducing and abrasion resistant performances than the PES/PI blend. Among all these composites, the 7.0 wt% EG/PES/PI composite demonstrates the best friction and wear properties (0.23, 5.68 × 10−16 m3/[N·m]) at evaluated temperatures. The noticeable improvement in abrasive property of EG/PES/PI composites at high‐evaluated temperatures stems from extraordinary porous microstructures and outstanding lubrication characteristics of EG particles as well as the formation of uniform self‐lubricating polymer tribofilms. This composite as antifriction and wear‐resistant materials possesses potential applications in high‐temperature engineering tribology, such as rolling bearing retainer, and so forth.