The Effect of Plasticization of Isoprene Rubber on the Degree of Vulcanization of Its Rubber Compounds

Abstract

Continuation of a series of works on the effect of plastication (P) of isoprene rubber (SKI-3) on the properties of rubbers. The influence of temperature T and time t of P on the degree of vulcanization (DV) of rubber filled with technical carbon has been studied. As before, P was carried out in a 5-liter rubber mixer of the company «HFM» in the range T = 30–130 0C and t = 30–600 s. The DV value was determined on the MDR 2000 (Alpha Technologies, UK) device by the difference between the maximum and minimum values of the elastic component of the complex torque. Equations describing the dependences of the values of DV of different fractions on the conditions of P are obtained. Changes in DV are compared with the previously published values of molecular weights (MM) of fractions. It is shown that with a decrease in MM, the value of the DV of super- and high-molecular fractions increases, and the DV of medium- and low-molecular fractions decreases. Explanations of these facts are proposed, considering the concepts of sulfur diffusion during vulcanization, and practical recommendations for achieving high or low values of DV are presented.