Silica Masterbatches Produced with Liquid Phase Mixing - Part II. Dynamic Stress-Softening Effect

摘要

The stress-softening effect of the vulcanizates has been generally investigated with quasi-static and large deformations. With regard to tire application, the dynamic stress applied is relatively small with high frequencies. Under dynamic deformations, the decrease in elastic modulus with increasing of strain, along with changing of hysteresis in terms of the loss tangent and the loss compliance, is another mode of stress-softening. Besides a single strain sweep, this type of dynamic stress softening can also be performed with repeated strain sweeps. This paper reports the dynamic stress-softening effect of the vulcanizates of SSBR/BR/silica masterbatch named EVEC (Eco-Visco-Elastomer composite) produced with liquid phase mixing is reported, taking the silica- and carbon black-filled vulcanizates prepared with conventional technology as references. With different modes of repeated strain sweeps, it is found that compared with the conventional vulcanizates, the new material shows rather weak softening effect, and a more efficient recovery of loss tangent and loss compliance during rest. This observation is explained based on the effect of polymer-filler interaction and filler agglomeration.