Molecular Design Of Functionalized Styrene-butadiene Copolymer And Its Interaction With Silica

It is imminent for the development of low-energy,high-safety green tires in recent years.As an ideal blending filler surface for rubber,the compatibility between silica and non-polar rubber is poor due to the cougulation of silica.At present,to improve the dispersion of silica through the functionalization of rubber is one of research highlights,and it is of great practical significance for the manufacture of green tires.In this thesis,the anionic copolymerization of 4-tert-butoxystyrene(t-BOS)and styrene and the anionic terpolymerization of 4-tertbutoxystyrene,styrene and butadiene were studied.Three in-chain functional rubber solutionpolymerized styrene-butadiene rubber(SSBR-tBOS)samples with different bounded t-BOS content were successfully prepared in the 10L polymerization reactor by using anionic polymerization method with divinyl benzene(DVB)as the coupling agent.The vulcanizate was obtained after plasticating,mixing and vulcanization of the SSBR-tBOS.The molecluar structure,molecular weight and its distribution of the prepared copolymers were characterized by proton nuclear magnetic resonance spectroscopy(1H-NMR),gel permeation chromatography(GPC)and infrared spectroscopy(FT-IR).The thermal stability and the glass transition temperature of the copolymers were determined by thermogravimetric analyzer(TGA)and differential scanning calorimetry(DSC).The Payne effect and vulcanization performance of the SSBR-tBOS compound,dynamic mechanical properties,physical and mechanical properties of the SSBR-tBOS vulcanizate were tested and compared with the tincoupled contrast SSBR which made in the Yanshan Corporation of SINOPEC.Finally,the binding energies of SSBR-tBOS/Silica and SSBR-OH/Silica composite models were calculated by using the molecular dynamics simulation software Materials Studio and the calculating results will provid theoretical guidance for the application of in-chain functional SSBR in the field of green tires.The results showed that the copolymerizaton reactivity of 4-tert-butoxystyrene was higher than that of styrene when the anionic copolymerization was carried out at-78℃,tetrahydrofuran(THF)as solvent.The molecular weight distribution index(PDI)of the copolymer was 1.10 when the temperature was-30℃ and the mass ratio of tetrahydrofuran and cyclohexane was 5/5(wt).The terpolymer with specific components can’t be carried out due to the low conversion rate conditions of butadiene at-78℃,THF as solvent.The endfunctionalized SSBR-tBOS were synthesized by using two-step method,with increaseing tBOS content,the PDI of the terpolymer increased(1.05-1.67).The terpolymer with low polydispersity(1.10-1.15)were successfully carried out at 30℃,cyclohexane as solvent.The terpolymerization reactivities were excellent and the distribution of t-BOS in the chain were uniform during the terpolymerization process.The initial decomposition temperature decreased with the increasing of t-BOS,while the glass transition temperature Tg of SSBR-tBOS increased.The Mooney viscosity of the raw rubbers were too low due to the small molecular weight of SSBR-tBOS.So the physical mechanical properties of SSBR-tBOS were poorer than that of reference sample.However,with increasing the density of the crosslinking network,the modulus at 100%elongation of the vulcanizates tended to increase.With increasing t-BOS content,the Payne effect of SSBR-tBOS was reduced and the dispersion of silica in the rubber matrix was excellent.The binding energies of SSBR-tBOS/Silica and SSBR-OH/Silica composite models were the highest when the t-BOS content or hydroxyl content was 9%.