Study On Synthesis And Application Of Trans-1,4-Polyisoprene By Solution Polymerization

Trans-1,4-polyisoprene(TPI)is a synthetic gutta percha,whose monomer is isoprene,and its molecular chains go with trans regularity,showing plastic properties at room temperature.Because TPI has the characteristics of double bond structure and chain flexibility,it can significantly improve the dynamic fatigue properties of rubber materials after mixing and vulcanization with general rubber materials.However,when the rubber products are used in the dynamic environment,the catalyst metal ions in the material will lead to the occurrence of aging phenomenon,so it is very important for the purifying TPI materials in the synthesis process.TPI could be successful synthesized by the solution slurry polymerization with supported titanium catalyst(TiCl4/MgCl2-AlR3)in this thesis,and this process was simple that had short reaction time.The suitable synthetic conditions for the process were explored by a series of polymerization experiments.The results showed that,when using the HZ type catalyst,polymerization temperature was 60 ?,the optimum polymerization conditions were: Al/Ti 50(molar ratio),monomer concentration 4 mol/L,Ti/Ip 3×10-4(molar ratio),prepolymerization time 30 min,reaction time 6 h,n-hexane chosed as solvent was the best.This study used a variety of post-processing purification methods to purify the synthetic TPI by solution slurry polymerization.The results showed that the metal elements in TPI could be reduced by using the ethanol washing method,and the residual content of Ti and Al was less than 300 ppm.As a result of TPI particles swelled and would happen together in the process of the synthesis,we explored the nano research of TPI.The size of TPI particles fell to 100 nm~100 um when combining dispersant hexadecyltrimethyl ammonium bromide(CTMAB)with isolation agent carbon black.The results of structure characteristics of TPI by analog amplification tests based on the above polymerization conditions showed that,trans structure content was more than 97%,melting point was 60~65 ?,crystallinity was 25~30%,relative molecular weight was 10~15×104,molecular weight distribution was 2~3.The results of performance tests of TPI by plastication showed that,Mooney viscosity was 110~120,density was 0.95~0.97 g/cm3,Shore A hardness was 95~97,tensile strength was 30~35 MPa,breaking elongation was 300~350%,tearing strength was 80~100 kN/m.Highly pure TPI affecting in the curing characteristics,mechanical properties,aging properties and dynamic fatigue properties of NR was investigated.The results showed that the vulcanization characteristics and mechanical properties of NR/TPI blends(80/20)basically remain decreased slightly compared with NR,while the dynamic fatigue properties increase to 3~4 times.In addition,the effects of TPI content and different formulations on the properties of NR/TPI blends were studied.Among them,when the content of TPI was 20 and the formulation was 2.5/1/30,the overall properties of NR/TPI blends were the best.