Impact of foaming agent and nanoparticle fillers on the properties of irradiated rubber

Abstract

Abstract A sponge rubber nanocomposite based on styrene–butadiene rubber (SBR)/nanoclay (montmorillonite, MMT) or nano-calcium carbonate (CaCO3) fillers with various foaming agent contents was produced by a simple technique, roll milling. The nanoparticles were examined by different techniques, such as X-ray fluorescence (XRF), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), and Fourier-transform infrared (FT–IR). The sponge rubber nanocomposites were characterized by scanning electron microscopy (SEM) image analysis before and after exposures to radiation doses, as well as by the XRD patterns for the unirradiated samples. The different properties of the obtained nanocomposites, including their foaming degree, tensile strength, elongation at break, and thermal conductivity, were also investigated. The foam composites containing nano-CaCO3 possessed the best cell and crosslinking densities and mechanical properties among the other composites, while its foaming degree was the lowest. The results indicated that the thermal conductivity was reduced by increasing the foaming agent concentration. However, it increased as the radiation dose increased, and the optimum radiation dose was obtained at 75 kGy. The foam containing MMT exhibited an intermediate behavior while high thermal conductivity was recorded for the foam containing the CaCO3 nanoparticles.