AC Electrical and Structural Properties of Polymethylmethacrylate/Aluminum Composites

Abstract

Different concentrations (i.e., 10, 20, 30, and 40 wt%) of Al metal are dispersed in polymethylmethacrylate (PMMA) matrix and the composite films are prepared by solution casting method. The frequency and temperature dependence of dielectric constant, dielectric loss, and conductivity of pure polymer and polymer composites filled with Al-metal filler are studied in the broad frequency range from 100 Hz to 10 MHz and in the temperature range 25—80°C. It is observed that the dielectric constant, dielectric loss, and electrical conductivity gradually increase with filler concentration and also with temperature and is explained in terms of hopping conduction mechanism. The electrical conductivity of the composites obeys universal power law model (i.e., σ = Af n), where n is power exponent. A comparison of dielectric constant values of PMMA/Al composites is made with predictions of theoretical models and it is observed that an empirical power equation gives a better fit to our results. Structural property of the composites is studied by means of X-ray diffraction. The results show that the crystallinity and crystalline size increase with increasing concentration of aluminum filler. Average surface roughness is observed to change with filler concentration as obtained from atomic force microscopy and scanning electron microscopy analysis.