Suppression of dielectric loss of PPE/HIPS alloys in microwave region by utilization of MgO filler

ABSTRACT The high‐frequency dielectric, thermal, and mechanical properties of poly(2,6‐dimethyl‐1,4‐phenylene ether)/high‐impact polystyrene (PPE/HIPS) alloys compounded with MgO filler were investigated as a function of MgO content. A comparison with isotactic polypropylene/MgO composites was also carried out. Composite samples without voids were successfully prepared by melt‐kneading and hot‐pressing processes. A reduction of dielectric loss (tan δ) to less than 10 −3 was achieved by adding 40 vol % of MgO to the PPE/HIPS alloys. The compositional dependencies of the real part of the dielectric constant (ε′), tan δ, and temperature coefficient of ε′ (TCε) showed correspondence with the Bruggeman theory. The decrease in thermal expansion with increasing filler concentration followed the logarithmic rule of mixture. The flexural moduli of the composites increased with MgO loading in accordance with the Nielsen theory. On the other hand, deteriorations were observed in flexural and Charpy impact strengths. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47315.