Characterization And Synthesis Of S-PB/TPB/TPI Blends With Surppoted Catalysts

Trans-1,4-polyisoprene, trans-1,4-polybutadiene and syndiotactic-1,2-poly- butadiene are semi-crystalline polydienes. Due to the unique structure and properties, they can be used in many fields. Supported catalyst is composed of main catalyst which is carried by inorganic compounds and polymer compounds, and the co-catalyst of alkyl aluminum. Through the supporting method, the main catalyst can be well dispersed on the surface of supporter, even to reach the monomolecular dispersion degree, which can increase the amount of activity center. Meanwhile, the supporter can make the stereotactic activity center more stable, and increase the isotacticity degree of polymers.Supported coordination catalyst SiO₂/Co(naph)2-Al(i-Bu)3-CS₂ was employed to catalyze the polymerization of Butadiene for the first time. Effects of different conditions on the polymerization of Bd were studied systematically. The results show that the stereospecific polymerization of Bd by supported catalyst in hydrogen gasoline could be conducted successfully, and the rate of polymerization was high. When c(Bd)=5.55mol/L, n(Co)/n(Bd)= 0.8×10-4, the conversion of 80.8% can be achieved in hydrogen gasoline at 0℃for 5 hrs. FT-IR, DSC, TGA, and WAXD were used to analyze the structure and property of s-PB.The homopolymerization of Bd and Ip by supported catalytic system, MgCl₂·SiO₂/TiCl4-Al(i-Bu)3 were carried out in hydrogen gasoline. Effects of different conditions on the polymerization of Bd were discussed systematically. For Ip/gasoline, when c(Ip)=3.33mol/L, n(Ti)/n(Ip)=6×10^-5, and n(Al)/n(Ti)=100, the conversion of Ip was 75.5% at 50℃for 20 hrs. For Bd, when c(Bd)=5.55mol/L, n(Ti)/n(Bd)=6×10-5, n(Al)/n(Ti)=100, the conversion of Bd was 93% at 30℃for 30 hrs in hydrogen gasoline. TPI and TPB obtained by supported catalytic system were characterized by means of FT-IR, 1H NMR, DSC and WAXD.It's well known that polymer blending is an attractive alternative for producing newpolymeric materials with desirable properties. The advantage of polymer blending are versatility, simplicity, and low cost. TPI, TPB and s-PB are all crystalline polymers. The melting point of TPB and s-PB are high. Especially for s-PB, its melting point is over 200℃, and due to the large amount of double bonds contained in the side chains of the polymeric molecules, which will cross-link at higher temperature(>150℃), hence it was difficult to be blended with other materials by mechanical methods. In this dissertation, TPI/s-PB blends were first obtained via in-situ polymerization with supported catalysts of SiO₂/Co(naph)2 and MgCl₂·SiO₂/TiCl4. It was found that TPI/s-PB blends can be prepared by different feed sequences. DSC, WAXD and FT-IR were used to characterize the structure of the blends. And the crystallization kinetics of TPI/s-PB blends were investigated . the results show that, in the isothermal crystallization process, the crystallization mode of TPI component might be the mixture of one-dimensional, needle-like and two-dimensional, circular, and s-PB acted as heterogeneous nucleation in the TPI matrix. Meanwhile, the crystallization rate of TPI increases with the increasing of s-PB. The curing properties of TPI/s-PB blends during the transition form plastic to elastomer were studied by sulfur vulcanizing system. It's found that with the increasing of s-PB, the vulcanizing time of TPI/s-PB blends gradually reduced. And the mechanical properties of TPI/s-PB blends were been tested.TPI/TPB blends were prepared with MgCl₂·SiO₂/TiCl4-Al(i-Bu)3 in polymerizer. The thermal property, crystallization and microstructure of the blends were analyzed by means of DSC, WAXD and SEM. The results of nonisothermal crystallization kinetics for TPI/TPB blends show that, with the increasing of cooling rate, each peak moves to low temperature. The crystallization of TPI and high temperature crystallization of TPB can both be divided into two stage, the primary crystallization stage and the secondary crystallization stage. During the primary stage, the crystallization mode of TPI is mainly three-dimensional growth mechanism with a combination of thermal and athermal nucleation. The crystallization mode of TPI in high temperature is also a three-dimensional growth with homogeneous nucleation. Meanwhile, the crystallization mode of TPB in low temperature is a combination of three-dimensional and two-dimensional growth. In the secondary stage, the Avrami exponents indicate the crystallization mode of TPI and TPB in high temperature are both a combination of one-dimensional, needle-like and two-dimensional, circular. TPI and TPB both have double bonds in their main chain, hence they can transfer form glass state to rubbery state by vulcanization. The property of sulfur vulcanization and mechanical properties for TPI/TPB blends have been studied.TPI/TPB/s-PB blends were also prepared by in situ polymerization with SiO₂/Co(naph)2 and MgCl₂·SiO₂/TiCl4 catalysts. The structure and property of the blends were characterized by means of DSC, WAXD and SEM. The vulcanization and mechanical properties for TPI/TPB/s-PB blends were analyzed. The results indicate, the blends with different rubber-plastic form can be obtained by controlling the curing time.