The kinetic of D,L-lactide polymerization in presence of biocompatible zirconium acetylacetonate initiator was studied by differential scanning calorimetry in isothermal mode at various temperatures and initiator concentrations. The enthalpy of D,L-lactide polymerization measured directly in DSC cell was found to be =-17.8±1.4 kJ mol. Kinetic curves of D,L-lactide polymerization and propagation rate constants were determined for polymerization with zirconium acetylacetonate at concentrations of 250-1000 ppm and temperature of 160-220 °C. Using model or reversible polymerization the following kinetic and thermodynamic parameters were calculated: activation energy =44.51±5.35 kJ mol, preexponential constant ln=15.47±1.38, entropy of polymerization =-25.14 J mol K. The effect of reaction conditions on the molecular weight of poly(D,L-lactide) was shown.
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| http://dx.doi.org/10.1002/open.202000101 | DOI Listing |
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