Crosslinking by peroxide and sulphur vulcanization: chemical mechanisms and reaction kinetic determination. a comprehensive numerical model

The work presents a comprehensive numerical model to optimize mechanical properties of thick rubber vulcanized items, comprising medium and high voltage electric cables and 3D devices. Several vulcanization systems are considered, including peroxides and accelerated sulphur. In the case of peroxides, both a genetic algorithm (GA) with zooming and elitist strategy and an alternating tangent (AT) approach are adopted to determine the optimal final mechanical properties (tensile strength) of 2D and 3D rubber items. The use of a mixture of peroxides is also taken into account, demonstrating that it helps in reducing the curing time and/or in increasing the optimal tensile strength in both core and skin of thick devices. For sulphur vulcanization, a mathematical kinetic model is presented to accurately predict the crosslinking density of vulcanized rubber. It bases on the actual reactions occurring in practice and allows to estimate the overall degree of vulcanization of real manufactured items.