Effect of 1,3-Diphenyl-guanidine (DPG) Mixing Step on the Properties of SSBR-silica Compounds

1,3-Diphenylguanidine (DPG) is commonly used as a secondary accelerator which not only acts as booster of cure but also activating silanization reaction. The aim of this study is to increase the interaction between silica and rubber by using DPG. In this study, mixing was proceeded in two steps. The T-1 compound is mixed DPG with silica and silane coupling agent in the kneader at high temperature which is named as 1 mixing step. T-3 compound is mixed DPG with curatives in the two-roll mill at low temperature which is named as 2 mixing step. The T-2 compound is mixed a half of DPG in 1 mixing step and the remainder is mixed in 2 mixing step. Total DPG content was equal for all compounds. When DPG is mixed with silica, silane coupling agent during the 1 mixing step, a decrease in cure rate and an increase in scorch time can be seen. This indicates that DPG is adsorbed on the surface of silica. during rubber processing. However, bound rubber content is increased and dynamic properties are improved. These results are due to the highly accelerated silanization reaction. However, there are no significant difference in 100%, 300% modulus.