Study On Properties Of Trans-polyisoprene And Copolymer Synthesized By Vanadium Catalyst System

Trans-1,4-polyisoprene(TPI)and trans-1,4-isoprene-butadiene copolymer(TPBI)were prepared by VCl3-Al(i-Bu)3-TiCl4 catalyst system synthesized by ourselves.The changes in crystalline properties,processing rheology,dynamic mechanical properties as well as mechanical properties of polymer by copolymerized with butadiene were studied in this paper.Polymer microstructure was characterized according to the 1H-NMR spectra and Fourier transform infrared analysis(FT-IR).Temperature transition and non-isothermal crystallization kinetics were tested by differential scanning calorimetry(DSC)while crystalline degree was measured by X-Ray Diffraction(XRD).Also the crystalline morphology of polymer was observed in polarizing microscope(POM).We could test the dynamic properties of both samples with RPA2000.Therefore,the crystalline properties,processing rheology performances as well as dynamic mechanical properties of TPI and TPBI prepared could be compared and analyzed.Then the results as follows were obtained:the use of vanadium catalyst system was proved to be effective in the preparation of trans-1,4-isoprene(TPI)and trans-1,4-isoprene-butadiene copolymer(TPBI).The glass transition temperature(Tg),crystalline melting enthalpy(?Hc)and degree of crystallinity of TPBI were lower than that of TPI.Crystalline morphology were both spherulites that were smaller and more uneven with-obvious holes defects in TPBI,which indicated less complete crystalline.With the increase of cooling rate polymer crystallization exothermic peaks moved to lower temperature with bigger peaks deformation width in the non-isothermal process.Under the same rate TPBI's crystallization appeared later with wider and smaller peaks.Crystallization activation energy ?E of both samples were calculated:?E(TPI)is 61.194KJ/mol and ?E(TPBI)is 72.722KJ/mol.Rheology of polymer processing were described by power-law equation.The result showed smaller non-Newtonian index m of TPBI/NR blend which meant more rubber characteristics.Mooney viscosity value of TPBI/NR is also smaller so that the torque values decreased and processing performance was improved.The mechanical test results indicated that TPBL/NR blend's tensile strength and wear resistance were improved.Tear strength increased significantly(TPBI content was 20pph).Better mechanical properties were obtained.Storage modulus,loss modulus and loss factor was sgreater in TPBI/NR blend than that of TPI/NR blend demonstrated in rubber process analyzer scanning of frequency,strain and temperature.