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Lactic acid based poly(ester‐urethanes): Use of hydroxyl terminated prepolymer in urethane synthesis
Author(s) -
Hiltunen Kari,
Seppälä Jukka V.,
Härkönen Mika
Publication year - 1997
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19970222)63:8<1091::aid-app16>3.0.co;2-9
Subject(s) - prepolymer , polymer chemistry , monomer , lactic acid , polymerization , molar mass distribution , lactide , condensation polymer , glass transition , polymer , materials science , ring opening polymerization , chemistry , polyurethane , organic chemistry , biology , bacteria , genetics
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 13 C‐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