| The silane-modified cold-emulsion styrene-butadiene (HSi-ESBR and Si-ESBR) was synthesized by using solution and reaction processing methods, respectively.The hydrosilylation of styrene-butadiene rubber using triethylsilane (Et3SiH) in the presence of tris(triphenylphosphine) rhodium chloride (RhCl(PPh3)3) was carried out at 100℃in toluene under N2. The structure of target product was characterized by IR, 1H NMR and 13C NMR. In addition, gel content and gel permeation chromatography were used to determine the chain properties of the product polymers. It showed that RhCl(PPh3)3 was highly selective toward catalyzing the hydrosilylation of the vinyl C=C bonds of the polymers. The degree of hydrosilylation could be controlled by appropriate adjustment of the [Rh]:[Silane]:[C=C] ratio, when the [Rh]:[Silane]:[C=C] =0.15:115:115 (mol/mol/mol),ζwas up to 63%. HSi-ESBRs were filled with carbon black or silica. Mooney viscosity, curing properties and mechanical properties of product polymers were investigated. It indicated hydrosilylation of ESBRs could greatly increase the curing reaction extent. When the degree of hydrosilylation was 63%, Tanδwas decreased from 0.193 to 0.130, and the fatigue heat build-up was decreased by 30%, indicating that the dispersion of sulfur and accelerant were improved by introducing -CH2CH3Si groups onto the polymer chain. Correspondingly, it made the crosslink destiny increase from 11.72×10-5 up to 29.96×10-5 mol·cm-1. Payne effect was much less clear than that of unmodified ESBR according to G'-strain scanning curves. Dynamic mechanical properties of hydrosilylated styrene-butadiene rubber were measured. According to the results of DMTA, when the degree of hydrosilylation was larger, tanδat 60℃had a great decrease, indicating lower rolling resistance. SEM observation of compounds showed better dispersion of silica in the rubber matrix.The silica modified cold-emulsion styrene-butadiene rubber (Si-ESBR) was synthesized in the presence of NaH and Et3SiCl. The effect of amounts of NaH and Et3SiCl and reaction time on the mechanical properties of Si-ESBR was discussed in this paper. It was found that the optimum reaction condition was: NaH 0.04mol, Et3SiCl 0.04mol, reaction time 15min; reaction temperature 80℃. Under these conditions, curing reaction extent of Si-ESBR was increased obviously; tearing strength was decreased by 0.2 MPa; ageing resistance performance of object product were improved. RPA results showed that Payne effect of Si-ESBR decreased obviously than that of unmodified ESBR. Due to the group of -Si-CH2CH3 attached onto the polymer chain, the filler network was improved effectively. |
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