Synthesis Of Star Poly(Styrene-co-Butadiene) Rubber With Multiple Arms Via Solution Polymerization

In recent years, the research about green tires has been main means to reduce energy consumption of vehicles. The high vinyl solution polymerized styrene butadiene rubber (SSBR) will play important role in green tires because of its advantages, such as good wet resistance and low rolling resistance. Vinyl content of SSBR can be achieved by adding polar modifier. Meanwhile, SSBR can overcome the cold flow of raw rubber and improve the processing properties of material by using coupling agents. So, in this paper, the micro structure and coupling reaction of poly(butadiene-co-styrene) which is synthesized with ethyl tetrahydrofurfuryl ether (ETE)?potassium tert-butoxide (t-BuOK)?sodium dodecyl benzene sulfonate (SDBS) as modifiers, divinyl benzene (DVB) as coupling agent will be discussed.Firstly, reaction kinetic of poly(butadiene-co-styrene) with ETE alone as the regulator and coupling reaction of different coupling agents, coupling time, temperature, molecular weight with DVB as coupling agent were investigated. The branching structures of coupled polymers on different coupling time were analyzed and characterized. The monomer conversion rate could reach 100% when reaction is only 25min. The coupling efficiency (CE) of DVB was better than conventional coupling agent tin chloride (SnCl4). CE of coupled polymers increased with increasing coupling time. CE changed a little at coupling temperatures 40-70?. CE decreased with the increase of molecular weight from 5×104 to 10×104. The method of adding metric DVB after reacting 1h is feasible to ensure higher CE and more convenient operation. The curve of lg(intrinsic viscosity) with lg(polymer molecular weight) for the uncoupled polymer was linear and accorded with Mark-Houwink equation. For the coupled polymers, those curves were not linear and the branching degree increased, branching ratio (g') decreased with increasing coupling time.Secondly, the micro structure and coupling reaction of poly(butadiene-co-styrene) were discussed with t-BuOK/ETE?SDBS/ETE/t-BuOK/SDBS/ETE as regulators and DVB as coupling agent. Results showed that the ability to adjust 1,2-structure of t-BuOK was weak and the effect of coupling reaction changed little; the ability to adjust 1,2-structure of SDBS was strong, but CE decreased with increasing usage of SDBS. When R of SDBS is 0.1 and R of ETE is 2, vinyl content is up to 69.7% and CE is 53.0%. When R of SDBS is 0.1 and R of ETE is 1, vinyl content is up to 62.0% same as ETE alone and CE is 53%. It is a good way to reduce the cost of ETE instead of SDBS. T-BuOK/SDBS/ETE was not better than SDBS/ETE.Last, two high vinyl SSBR with different coupling efficiency rubber were synthesized by reactor. The two rubbers were vulcanized and prepared for mechanical test and dynamic mechanical test. The results showed that the comprehensive performance of the higher coupling efficiency SSBR is better than the lower and SSBR2305.