Synthesis Of Polylactides Catalyzed By The Solid Superacid Catalyst

Synthesis of polylactides with direct condensation polymerization catalyzed byrare-earth oxide has been studied. The results show Y₂O₃ is better than otherrare-earth oxides. The solid superacid catalyst SO₄^2-/TiO₂-Ce⁴⁺ was prepared by twophase precipitation and reparation conditions of the catalyst suitable for the synthesisof poly(lactic acid) through the polycondesation of lactic acid monomer were 0.175mol/L immersing concentration of H₂SO₄ for 10 h and 500℃calcinationtemperature for 4 h. The above catalyst was firstly used for catalytic synthesis ofpoly(lactic acid) through the polycondesation of lactic acid monomer. The effects ofreaction temperature, reaction time, reaction pressure and catalyst amount onpolycondesation of lactic acid were studied. The optimum reaction conditions wereobtained, that is, the amount of catalyst was 0.174ï¼…of lactic acid, prepolymerizationfor 5h under the condition of 120℃, 2000Pa, then polymerization for 15h under180℃, 1000Pa, and last polymerization for 20h under 120℃, 500Pa. The viscosityaverage molecular weight of poly(lactic acid) is 1.39×10⁴.This article research the Mechanism of synthesis of Polylactides with DirectCondensation Polymerization Catalyzed by SO₄^2-/TiO₂-Ce⁴⁺, The experimental resultindicated that: the Mechanism of synthesis of Polylactides with Direct CondensationPolymerization Catalyzed by SO₄^2-/TiO₂-Ce⁴⁺is acidic polymerization, The acidityof catalyst stronger will synthesizes the higher molecular weight Polylactides;Synthesis the Polytides by opening the chain of Polylactic,catlysted by SO₄^2-/TiO₂-Ce⁴⁺.Drying the PLA which molecular weight is 5000, extruding from the twinextrusion, moulding it, testing the capability by material test machine.SolidPolycondensation have a positive effection on Synthesis of Polylactic acid as well.