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Blends of poly(ε-caprolactone-b-lactic acid) and poly(lactic acid) for hot-melt applications

Authors

  • Mikael Stolt,

    Corresponding author
    1. Hycail B.V., Industrieweg 24-1, 9804 TG Noordhorn, The Netherlands
    2. Åbo Akademi University, Laboratory of Polymer Technology, Piispankatu 8, 20540 Turku, Finland
    • Hycail B.V., Industrieweg 24-1, 9804 TG Noordhorn, The Netherlands
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  • Mikko Viljanmaa,

    1. Kiilto Oy, P.O. Box 250, 33101 Tampere, Finland
    2. Tampere University of Technology, Institute of Biomaterials, P.O. Box 589, 33101 Tampere, Finland
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  • Anders Södergård,

    1. Hycail B.V., Industrieweg 24-1, 9804 TG Noordhorn, The Netherlands
    2. Turku Center for Biomaterials, Itäinen pitkäkatu 4 B (PharmaCity), 20520 Turku, Finland
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  • Pertti Törmälä

    1. Tampere University of Technology, Institute of Biomaterials, P.O. Box 589, 33101 Tampere, Finland
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Abstract

The condensation reaction product of poly(lactic acid) (PLA) and a hydroxyl-terminated four-armed poly(ε-caprolactone) (PCL) was studied by size-exclusion chromatography, DSC, and NMR. The use of both L-lactic acid (LLA) and rac-lactic acid (rac-LA) was studied and the use of two different catalysts, stannous 2-ethylhexanoate [Sn(Oct)2] and ferrous acetate [Fe(OAc)2], was also investigated. The thermal stability and adhesive properties were also measured for the different formulations. The characterization results suggested the formation of a blend of PLA and a block-copolyester of PLA and PCL. The results further indicated partial miscibility in the amorphous phase of the blend showing only one glass-transition temperature in most cases, although no randomized structures could be detected in the block-copolymers. The polymerization in the Fe(OAc)2-catalyzed experiments proceeded slower than in the Sn(Oct)2-catalyzed experiments. The discoloring of the polymer was minor when Fe(OAc)2 was used as catalyst, but significant when Sn(Oct)2 was used. The ferrous catalyst also caused a slower thermal degradation. Differences in the morphology and in the adhesive properties could be related to the stereochemistry of the poly(lactic acid). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 196–204, 2004

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