Optical and dielectric dispersion parameters of general purpose furnace (GPF) carbon black reinforced butyl rubber

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 diffraction (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 significant changes in the composite structure. Some structural parameters were calculated for the XRD fundamental peak. The crystallite size increased significantly with the increase in carbon black concentration. This suggested a tendency of the polymer toward a more crystal state. Analysis of refractive index dispersion was carried out using Wemple–DiDomenico single effective oscillator model. The energy of effective single oscillator (\(E_{\text{o}}\)) and the dispersion energy (\(E_{\text{d}}\)) were estimated for the composites of different CB loadings. Accordingly, the moments of optical spectra, static and high-frequency dielectric constants were calculated. The variation of the real part \(\varepsilon_{1}\) and imaginary part \(\varepsilon_{2}\) of the complex dielectric function with the incident photon wavelength was investigated. The recorded values of \(\varepsilon_{1}\) were greater than the values of \(\varepsilon_{2}\). The dielectric energy loss was specified by means of three important parameters: volume energy loss function, surface energy loss function and dielectric loss factor (\(\tan \delta\)). The dielectric relaxation time \(\tau\) and plasma frequency were studied as a function of incident photon wavelength for different composite samples. There was a great dependence of \(\tau\) on the wavelength and amount of the carbon black in the composite.