The preparation of multifunctional accelerators derived from tea phenols and their use in rubber compounds

Tea polyphenols (TPs) are natural compounds extracted from tea trees whose molecular structures possess many phenolic hydroxyl groups, and therefore are highly reactive. Based on the principle of the Mannich reaction, two types of multifunctional accelerators (Tea polyphenols-mercaptobenzothiazole [TPM] and Tea polyphenols-N-tert-butylbenzothiazole-2-sulphenamide [TPN]) were synthesized by the reaction of TPs with 2-mercaptobenzothiazole and N-tert-butylbenzothiazole-2-sulphenamide, respectively. The chemical structures of TPM and TPN were characterized using Fourier transform infrared spectroscopy, and the curing activity was measured using a vulcameter. The results showed that TPM and TPN had been synthesized successfully and possessed curing activity similar to that of traditional accelerators. TPM and TPN were then used in silica/rubber compounds to determine their effects on processing and on physiomechanical and antiaging properties. The results showed that TPM and TPN improved the curing rate of silica compounds and also improved the dispersion of silica in a rubber matrix as observed using transmission electron microscopy. Furthermore, the retention of tensile strength was higher for TPM and TPN vulcanizates after air aging than it was for the control sample. These results indicated that TPM and TPN, which incorporated the functions of a curing accelerator, a silica surface modifier, and an antidegradant, were new multifunctional accelerators for silica/rubber compounds.