Abstract
The author tries to apply a new method to characterize the reinforcing effect of fillers on basis of the Mullins softening and recovery, followed by the evaluation of the stress-elongation curves obtained after repeated deformation cycles and heat treatments of various duration. The apparent activation energy of the recovery process, i.e., the reformation of physical bonds after Mullins softening, was between 30-60kJ/mol. It is predominantly a physical process. By the evaluation of the stress-strain curves according to the Mooney-Rivlin equation, it is established that the constant C1 of the equation depends primarily on the number of the active network chain segments of the stable chemical network formed during vulcanization, which is also the case in filled vulcanizates. On the other hand, constant C2 of the equation depends on the rubber-filler physical interaction, and on the number of effective network chain segments determined by chain entanglements. As these physical network point undergo changes during the deformation, the value of C2 also changes. The constant C2 can be used as a general parameter for the characterization of the activity, the reinforcing effect of fillers.
