Electrical and Mechanical Properties of Some Composites with Polymeric Matrix

摘要

The present study aims to investigate the dielectric properties as well as the mechanical properties of polymerthyl methacrylate-carbon black and polyester-carbon black composites using semi-reinforcing furnace (SRF) and high abrasion furnace (HAF) carbon blacks. The permittivity #epsilon#' was found to increase by increasing carbon black content and showed anomalous dispersion. The absorption spectra (#epsilon#'' vs. frequency) from 100 Hz to 10 MHz were analyzed using a computer program based on Frohlic terms. Four absorption regions were obtained for either the polymer matrix or loadded samles. The first region in the lower frequency range could be attributed to Maxwell-Wagner effect resulting from the differences inthe conductivities of the ingredients of the composite. The second and third regions inthe higher frequency range could be attributed to the large and small aggregates caused by movements of the main chain. The fourth regionmay occur due to segmental rotation (ester group or carbonyl group) or local twisting motion of the main chain. At higher carbonblack concentration, the relaxation time for different regions except that for Maxwell-Wagner effect became higher and carbon black seems to interact with the polymer matrix giving rise to large aggregates resulting high relaxation time. The mechanical properties for te investigated samples were also examined, the results showed that the tensile strength is higher inthe case of smaller particle size carbon black HAF. This could be attributed to a good incorporation of carbon black of small particle size into the polymer matrix. Also, the morphology study indicates the presence of aggregates and some arrangements on adding carbon black.