Dynamic mechanical and dielectric relaxation characteristics of microcellular rubber composites

An in‐depth study of the surface characteristics of novel conductive carbon black Ensaco 350G has been carried out using XPS and high‐resolution vacuum FTIR. Both methods showed the existence of oxygen containing surface groups like carboxyls, carbonyls, etc. Dynamic mechanical analysis and dielectric relaxation spectra of conductive carbon black (Ensaco 350G) reinforced microcellular EPDM composites were used to study the relaxation behavior as a function of temperature (−90 to +100°C) and frequency (100–106 Hz). The effect of filler and blowing agent loadings on dynamic mechanical and dielectric relaxation characteristics has been investigated. The effect of filler and blowing agent loadings on glass transition temperature was marginal for all the composites (Tg value was in the range of −37 to −32°C), which has been explained on the basis of relaxation dynamics of polymer chains in the vicinity of fillers. The variation in the real and imaginary parts of the complex impedance with frequency has been studied as a function of filler and blowing agent loading. Additionally, an in‐depth study of the surface characteristics of the filler using XPS, high‐resolution vacuum FTIR and Raman spectra is also reported.