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Studies on Direct Synthesis of Poly(Lactic Acid) and Its Copolymer Through Melt Polycondensation

Author: NingXiaoZuo
Tutor: LiZhiYi
School: Dalian University of Technology
Course: Chemical Process Equipment
Keywords: Direct melt polycondensation Synthesis Characterization PDLLA PLGA
CLC: TQ316.33
Type: Master's thesis
Year: 2010
Downloads: 169
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Abstract


Polylactic acid has good biocompatibility and biodegradability , is widely used in tissue engineering scaffolds , drug delivery systems , biodegradable medical suture lines in the biomedical field , with good prospects for development . D , L - LA as raw material , synthesized by direct melt polycondensation of PDLLA , the shortcomings of poor polylactic acid material hydrophilic , to D , L - LA and GA as raw material , the PLGA was synthesized by the same process , and conducted a series of characterization of the product synthesized by means of FTIR, 1H-NMR, DSC, XRD, GPC . The specific contents and results are as follows: (1) The absence of a catalyst under atmospheric pressure directly to the melt polycondensation reaction kinetics behavior . Under the condition of 122 ℃ , D , L - LA 's direct polycondensation reaction kinetic equation LNR = -11.03 2.958lnc , reaction order n = 2.958 , the reaction rate constant κ = 1.61 × 10-5L2 · mol-2 · min-1 , according to the different temperatures of the reaction rate constant , the activation energy E = 104.34 kJ / mol ; under the conditions of 130 ° C , D , L - LA and GA direct polycondensation reaction kinetic equation lnr = -10.09 2.403lnc , reaction series n = 2.403 , the reaction rate constant k = 4.13 × 10 - 5L2 · mol -2 · min -1 , according to the reaction rate constant at different temperatures to obtain a reaction activation energy E 92.45kJ/mol . (2 ) D , L - LA as raw material , synthesized by direct melt polycondensation of PDLLA . In optimum conditions : of SnCl2 amount of 0.6% ( accounting for the mass fraction of the monomer ) , reaction temperature 160 ℃, reaction pressure of 1000 Pa , reaction time 10 h , synthetic viscosity average molecular weight of PDLLA 15032 . (3) to the D , L - LA and GA as raw material, the PLGA synthesized by direct melt polycondensation . Under optimum conditions : the amount of SnCl2 0.5% ( mass fraction) of the prepolymer of the reaction temperature of 165 ° C , the reaction pressure of 1000 Pa , reaction time 9 h , synthesized viscosity-average relative molecular mass of 9247 PLGA70/30 . By the introduction of the static contact angle analysis , GA segments , so that the static water contact angle decreased from 76 ° to 63 ° , and effectively improve the hydrophilicity of the PDLLA .

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