Modeling of Vulcanization Kinetics and Deformation–Strength Properties of Peroxide Vulcanizates of Nitrile–Butadiene Rubbers

Mathematical modeling of the kinetics of peroxide vulcanization of rubbers based on butadiene–nitrile rubbers and their deformation–strength properties has been carried out. The modeling results are compared with the experimental data obtained for carbon black-filled compositions based on NBRS-40AMN rubber, including the vulcanizing agent 1,4-di(tert-butylperoxyisopropyl)benzene in different dosages. The mathematical model of the vulcanization kinetics of the compositions relies on the analysis of the formal kinetic scheme of radical reactions occurring during peroxide vulcanization in the presence of air oxygen. Using this model the influence of oxygen on the ratio of carbon–carbon and ether–ether crosslinks in the formed vulcanization network is analyzed. To describe the deformation curves of peroxide vulcanizates with different content of the vulcanizing agent, a model based on the series decomposition of the network strain energy by invariants of the left Cauchy–Green strain tensor and including the linear viscoelasticity equation is proposed. The vulcanizate breakdown process is characterized by a kinetic equation in which a network deformation model is used which allows an adequate description of the deformation curves of crosslinked elastomers up to failure. By analyzing the dependences of the model parameters on the content of the vulcanizing agent, conclusions are made about changes in the structure of the vulcanization network with increasing degree of crosslinking.