Carbon - Carbon Key Coupling Of Conjugated Diene - Styrene Copolymer, Structure And Properties

Bond of the Sn-C in SSBR coupled with tetrachloride tin, namely tin coupled-SSBR, is easy broken by heat or shearing force, as a result the molecular weight of the Sn-SSBR were decreased, the mechanical properties were declined. In this paper, new diene-styrene copolymers coupled through carbon-carbon bond with novel coupling agent -acryloyl chloride ,were synthesized, and the mechanical properties and dynamic viscoelastic properties of the polymers were improved to some extent.Acryloyl chloride(AC), methacryloyl chloride, glycidyl methacrylate and allyl chloride were used as coupling agents for SSBR, and the star-polymers were prepared when the coupling agent was acryloyl chloride, while the others as coupling agents the obtained polymers mainly composed of the coupling of two prepolymers and with few star-like polymers.Mechanism of the reaction of living polystyrene with acryloyl chloride were investigated. It was found that the double bond, carbonyl bond, acyl chloride bond in the acryloyl chloride were all involved in the coupling reaction, and mechanism of the coupling reaction were effected by the amount of the acryloyl chloride used in the reaction.The effect of the amount of the acryloyl chloride, the molecular weight of living prepolymers, the time and temperature of coupling raction, the amount of THF, the monomer concentration, and different chain end group on the coupling reaction were studied. Cyclohexane and extracted oil as solvent, the optimism conditions of the coupling reaction were AC/BuLi=0.7~10 (mole ratio), temperature 50~60癈,time 60min,THF/BuLi<50 (mole ratio), [M]=12%(wt);the optimism coupling reaction conditions using 2 liter reactor were comply with above-mentioned conditions.The obtained SSBR and random SIBR coupled with acryloyl chloride respectivly were characterized by IR and 'H-NMR. The random distribution of the styrene unit in polymers were proved and the composition obtained by NMR were nearly as same as that of input ratio of the polymers.The mechanochemistry of SSBR coupled with AC during mastication were studied and the molecular chain were broken during mastication, as a result that the molecular weight of the polymer were declined ,the GPC curve were changed. But thebehavior of the SSBR coupled with AC were like that of ESBR to some extent other than Sn-SSBR.Mechanical and dynamic viscoelasticity of SSBR and SIBR coupled with acryloyl chloride were studied respectively. Both rubbers with excellent wet traction and low rolling resistance and good mechanical properties were confirmed and both of them are excellent tread rubbers. The typical example of SSBR coupled with AC were with modulus at 300% 17.7 MPa, tensile strength 22.9MPa, tear strength 39.5MPa, elongation 500%, tan 5 (0 ) 0.4782, tan 5 (60 ) 0.1049; The typical example of SIBR coupled with AC were modulus at 300% 15.4 MPa, tensile strength 24.3MPa, tear strength 40.4MPa, elongation 480%, tan 6 (0 0.701, tan 6 (60) 0. 117.The effect of chain end modification of SSBR on viscoelasticity were also studied. It was found that viscoelasticity of SSBR at high temperature were improved by chain end modification when the molecular weight of SSBR were relatively low (nearly 105), and tan 5 (60 ) were went down. And when the the molecular weight of SSBR were relatively high (nearly 2xl05), the improvement were less effective.