Lactic acid based poly(ester-urethane) : modification via copolymerization, chain linking and blending

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en Kylmä, Janne 2012-02-13T12:21:22Z 2012-02-13T12:21:22Z 2001-05-11
dc.identifier.isbn 951-22-5906-0
dc.identifier.issn 1239-0518
dc.description.abstract The properties of biodegradable lactic acid based poly(ester-urethanes), PEU, were chemically and physically modified and the structure-property relationships investigated. The heat resistance of PEU was improved by copolymerization of lactic acid with DL-mandelic acid. The glass transition temperature of poly(L-lactic acid-co-DL-mandelic acid-urethanes) showed a marked increase with increased mandelic acid composition. Molecular weight depression was attributed to the steric hindrance of the bulky phenyl group of mandelic acid. Novel biodegradable and thermoplastic poly(ester-urethane) elastomers were synthesized by the copolymerization of lactic acid and ε-caprolactone. Properties, such as glass transition temperature and mechanical properties were strongly dependent on the composition of the copolymer. Small amounts of ε-caprolactone increased the strain of PEU, and at higher caprolactone content the poly(L-lactic acid-co-ε-caprolactone-urethane), P(LA/CL)U, exhibited elastomeric properties, having lower strength but significant elongation. The rheological properties of PEU were enhanced by modification of the structure of the polymer chains. An increase in the amount of 1,6-hexamethylene diisocyanate (HMDI) as a chain extender caused branching, which was revealed by the broadened MWD and increased shear thinning at low frequencies. The chain linking technology for lactic acid prepolymers was further developed with the use of highly effective carboxyl and hydroxyl reactive chain extenders. Reaction between 2,2'-bis(2-oxazoline) (BOX) and the carboxyl groups of the lactic acid oligomer led to a hydroxyl terminated prepolymer with low acid value, which provided a significant increase in molecular weight in the HMDI linking reaction. The introduction of oxamide groups into the polymer structure increased the chain stiffness, which was detected in enhanced mechanical properties and an increase in the glass transition temperature. The impact strength of poly(ester-urethane) was significantly improved by blending. The toughening was achieved with a finely dispersed P(LA/CL)U or copoly(L-lactide/ε-caprolactone) elastomer phase in the matrix PEU. Tensile modulus and strength showed a downward trend as a function of rubber content but remained at an acceptable level. Good compatibility and interactions at the rubber-matrix interface were observed. The relationship between phase separation and mechanical properties of rubber-toughened blends was investigated. Composition of the elastomer, i.e. ε-caprolactone content, was found to determine the formation of the heterophase structure. The degree of crosslinking in the P(LA/CL)U rubber was another important factor in the impact modification. Furthermore, the balance between impact strength and stiffness of the poly(ester-urethane) composites was considerably improved by the addition of particulate or fibrous fillers as a third component. en
dc.format.extent 47, [70]
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher Helsinki University of Technology en
dc.publisher Teknillinen korkeakoulu fi
dc.relation.ispartofseries Acta polytechnica Scandinavica. Ch, Chemical technology series en
dc.relation.ispartofseries 282 en
dc.relation.haspart Kylmä, J., Härkönen, M., and Seppälä, J. V., The Modification of Lactic Acid Based Poly(ester-urethane) by copolymerization, J. Appl. Polym. Sci. 63 (1997) 1865-1872.
dc.relation.haspart Kylmä, J. and Seppälä, J. V., Synthesis and Characterization of a Biodegradable Thermoplastic Poly(ester-urethane) Elastomer, Macromolecules 30 (1997) 2876-2882.
dc.relation.haspart Hiljanen-Vainio, M., Kylmä, J., Hiltunen, K., and Seppälä, J. V., Impact Modification of Lactic Acid Based Poly(ester-urethanes) by Blending, J. Appl. Polym. Sci. 63 (1997) 1335-1343.
dc.relation.haspart Kylmä, J., Hiljanen-Vainio, M., and Seppälä, J. V., Miscibility, Morphology and Mechanical Properties of Rubber Modified Biodegradable Poly(ester-urethanes), J. Appl. Polym. Sci. 76 (2000) 1074-1084.
dc.relation.haspart Kylmä, J. and Seppälä, J. V., Ternary Phase Poly(ester-urethane)/Elastomer/Filler Composites, J. Appl. Polym. Sci. 79 (2001) 1531-1539.
dc.relation.haspart Helminen, A., Kylmä, J., Tuominen, J., and Seppälä, J. V., Effect of Structure Modification on Rheological Properties of Biodegradable Poly(ester-urethane), Polym. Eng. Sci. 40 (2000) 1655-1662.
dc.relation.haspart Kylmä, J., Tuominen, J., Helminen, A., and Seppälä, J., Chain Extending of Lactic Acid Oligomers. Effect of 2,2'-Bis(2-oxazoline) on 1,6-Hexamethylene Diisocyanate Linking Reaction, Polymer 42 (2001) 3333-3343.
dc.subject.other Chemistry en
dc.title Lactic acid based poly(ester-urethane) : modification via copolymerization, chain linking and blending en
dc.type G5 Artikkeliväitöskirja fi
dc.description.version reviewed en
dc.contributor.department Department of Chemical Technology en
dc.contributor.department Kemian tekniikan osasto fi
dc.subject.keyword biodegradable polymers en
dc.subject.keyword poly(ester-urethane) en
dc.subject.keyword lactic acid en
dc.subject.keyword polycondensation en
dc.subject.keyword copolymerization en
dc.subject.keyword chain extending en
dc.subject.keyword blending en
dc.subject.keyword impact-modification en
dc.identifier.urn urn:nbn:fi:tkk-002784
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.type.ontasot Doctoral dissertation (article-based) en
dc.contributor.lab Laboratory of Polymer Technology en
dc.contributor.lab Polymeeriteknologian laboratorio fi

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