Polym. Bull. https://doi.org/10.1007/s00289-018-2353-7 1 3 ORIGINAL PAPER Optical and dielectric dispersion parameters of general purpose furnace (GPF) carbon black reinforced butyl rubber K. Alfaramawi 1,2 Received: 10 January 2018 / Revised: 10 April 2018 / Accepted: 30 April 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract Optical and dielectric dispersion parameters for butyl rubber–general purpose furnace carbon black (IIR-GPF CB) composites with various carbon black (CB) concentrations were determined using ultraviolet transmittance spectra. X-ray difraction (XRD) for the composite samples was measured in the 2θ range from 5° to 50°. There was a slight increase in the XRD peak intensity by increasing CB content indicating some signifcant changes in the composite structure. Some struc- tural parameters were calculated for the XRD fundamental peak. The crystallite size increased signifcantly with the increase in carbon black concentration. This sug- gested a tendency of the polymer toward a more crystal state. Analysis of refractive index dispersion was carried out using Wemple–DiDomenico single efective oscil- lator model. The energy of efective single oscillator ( E o ) and the dispersion energy ( E d ) were estimated for the composites of diferent CB loadings. Accordingly, the moments of optical spectra, static and high-frequency dielectric constants were cal- culated. The variation of the real part  1 and imaginary part  2 of the complex die- lectric function with the incident photon wavelength was investigated. The recorded values of  1 were greater than the values of  2 . The dielectric energy loss was speci- fed by means of three important parameters: volume energy loss function, surface energy loss function and dielectric loss factor ( tan ). The dielectric relaxation time  and plasma frequency were studied as a function of incident photon wavelength for diferent composite samples. There was a great dependence of  on the wavelength and amount of the carbon black in the composite. * K. Alfaramawi kalgarmawy@ksu.edu.sa 1 Deanship of Scientifc Research, King Saud University, Riyadh 11451, Saudi Arabia 2 Department of Physics, Faculty of Science, Alexandria University, Alexandria, Egypt