Improving the electrical and mechanical properties of poly(phenylene sulfide) via reactive blending with an iodine-terminated fluoroelastomer

Abstract To improve the flexibility and electrical insulation of poly(phenylene sulfide) (PPS), a candidate insulating material for electric vehicle drive motors under high-temperature conditions, blends with fluoroelastomers (FEPMs) were investigated. Owing to the inherent immiscibility of PPS and FEPM, reactive blending using an iodine-terminated FEPM (mFEPM) was also evaluated to improve interfacial compatibility. The PPS/FEPM blend showed an improved partial discharge inception voltage (PDIV); however, coarse phase separation and poor interfacial adhesion were also observed. In contrast, PPS/mFEPM blends exhibited significant refinement of the dispersed phase and a more uniform morphology, suggesting in situ copolymer formation at the interface. Furthermore, although the incorporation of mFEPM significantly accelerated the crystallization rate of PPS, unlike FEPM, the flexural fatigue resistance improved dramatically. Regarding the PDIV, the PPS/mFEPM blend, like the FEPM blend, maintained high values even at high temperatures of up to 150 °C, demonstrating excellent insulation reliability even under severe operating conditions. These findings demonstrate that PPS/mFEPM blends are highly promising insulating materials capable of simultaneously achieving mechanical flexibility and electrical reliability in high-temperature environments.