Influence of plasticizer on the dielectric properties of polypropylene/carbon black composites

Abstract

The addition of plasticizers can improve the dispersion of conductive fillers in polymer composites. In this work, the effect of polyethylene glycol dimethyl ether (PEGDME) plasticizer on the dielectric properties of poly(propylene)/carbon black (PP/CB) composites was investigated. PP/CB composites with varying content of CB from 0 to 15 wt% were melt-mixed. PEGDME plasticizer (0 to 5 wt%) was introduced into the PP/CB composites to reduce CB particle agglomeration and facilitate CB dispersion in the polymer matrix. The electrical conductivity and dielectric constant of PP/CB composites with and without plasticizer were studied. CB loading improved the electrical conductivity and dielectric constant of the composites; however, the addition of PEGDME reduced their values. Scanning electron microscopy images revealed that the PEGDME dispersed the CB particles and hindered the continuous CB conductive network formation. Additionally, the effect of temperature on dc conductance of PP/CB composites was also investigated. The dc conductance increases when the temperature increases from 303 °K to 343 °K and then decreases with further temperature increments.