Effect of Aging Conditions and Rubber Waste Content on the Mechanical Properties and Structure of Montmorillonite/Acrylonitrile Butadiene Rubber Nanocomposites

The research described in the present work investigated the effect of thermal and photoaging and rubber waste content on the properties of acrylonitrile-butadiene rubber modified with montmorillonite (MMT). The MMT was mixed with plasticizer before the compounding in two roll mills. The modulus at 300% strain of samples without scrap maximally increased by 50% and 30% after thermal and photoaging, respectively, most probably due to an increase in the crosslink density. The maximum increases of the modulus, measured at 300% strain, of the unaged and aged rubber nanocomposite were exhibited by samples which each contained 10 wt.% of rubber waste. The MMT nanoparticles, well dispersed in the matrix, combined with good interfacial interaction between the different components, led to relative retention of the thermal and photo-oxidation aging coefficients and the large shape retention coefficient of the tested samples. Fourier transform infrared spectra showed that the crosslinking of the rubber nanocomposites containing waste occurred through the nitrile groups and C = C double bonds under the influence of aging. Scanning electron microscopy micrographs indicated that the MMT nanoparticles were uniformly embedded and well dispersed in the matrix. The rough and homogeneous fracture surfaces of the nanocomposite samples were not affected by incorporated waste. As a result of UV irradiation and thermal heating, aggregates were less visible and the fracture surfaces more homogeneous and compact.