Synthesis Of Li-Polyisoprene Rubber And Preparation Of Its Latex

The process for the preparation of polybutadiene rubber artificial latex(BRL) is researched and the emulsifying effectiveness of different emulsifying systems is studied in this thesis. Then the conditions of producing BRL are optimized and used to produce Ti-polyisoprene rubber latex(Ti-IRL). The solvent removal of coarse emulsion and concentrating of dilute latex are studied as well. In the last portion of this thesis Li-polyisoprene is synthesized by anionic polymerization and its latex(Li-IRL) is produced by the conditions used to producing BRL and Ti-IRL. The conclusions are as belows:1) The microstructures of polyisoprene are about74%Cis-1,4content,19%Trans-1,4content and6%3,4content when isoprene is initiated by n-BuLi with no stirring nor polar additive and the temperature is50℃. The monomer is10%by weight of the solution.2) The emulsifying system containing emulsifying agent B(B) and emulsifying agent A(A) is the most effective emulsifying agent, particularly when the ratio is1:4by weight.3) When BR cement is emulsified it is necessary to use a oil-water ratio of1-2by weight and emulsifying agent of1.0%～2.0%by weight of water phase. The average diameter of dilute BRL is420-680nm.4) When Ti-IR cement is emulsified it is necessary to use a oil-water ratio of1-2by weight and emulsifying agent of1.0%～2.0%by weight of water phase. A second-emulsifying agent, Span-80, is used when producing Ti-IRL and the dosage is0.10%～0.20%by weight of water.The average diameter of dilute Ti-IRL is about440nm.5) When Li-IR cement is emulsified it is necessary to use a oil-water ratio of1-2by weight and emulsifying agent of1.5%～5.0%by weight of water phase. A second-emulsifying agent, Span-80, is used and the dosage is0.15%～0.50%by weight of water. The average diameter of dilute Li-IRL is about350-550nm.6) The coarse emulsion is distilled at normal pressure first and then slight vacuum to remove solvent with a stirring speed of200-400rpm and the temperature is73-75℃. Thus the solvent is completely removed.7) The dilute latex is centrifuged10minutes on5000rpm and the solids content of the concentrated latex is82%～83%.