Lactic acid based poly(ester-urethanes): Use of hydroxyl terminated prepolymer in urethane synthesis
Autor: | Mika Härkönen, Jukka Seppälä, Kari Hiltunen |
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Rok vydání: | 1997 |
Předmět: |
chemistry.chemical_classification
Lactide Materials science Polymers and Plastics General Chemistry Polymer Surfaces Coatings and Films Lactic acid chemistry.chemical_compound Monomer chemistry Polymerization Polymer chemistry Materials Chemistry Organic chemistry Molar mass distribution Glass transition Prepolymer |
Zdroj: | Journal of Applied Polymer Science. 63:1091-1100 |
ISSN: | 1097-4628 0021-8995 |
Popis: | We studied a two step process for lactic acid polymerization: in the first step, the lactic acid is condensation polymerized to a low molecular weight hydroxyl terminated prepolymer and then the molecular weight is raised by joining prepolymer chains together using diisocyanate as the chain extender. The resulting polymer is a thermoplastic poly(ester-urethane). The polymer samples were carefully characterized with 13C-NMR, GPC, DSC, and IR. The results indicate that high conversions of lactic acid can be achieved, as well as independent control of the stereostructure, long chain branches, molecular weight average, and molecular weight distribution. Lactic acid is converted into a poly(ester-urethane) with a weight average molecular weight as high as 390,000 g/mol and a glass transition temperature of 53.7°C. The analyzed content of the monomer in the prepolymer is less than 1 mol % and the lactide content 2.4 mol %, while the final poly(ester-urethane) is essentially monomer and lactide free. The mechanical properties of the poly(ester-urethane) are comparable to those of polylactides. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1091–1100, 1997 |
Databáze: | OpenAIRE |
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