Modification of birch xylan by lactide-grafting
2012 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, Vol. 27, no 3, 518-524 p.Article in journal (Refereed) Published
4-O-methylglucuronoxylan, isolated by ultrafiltration from a birch kraft cooking liquor, was delignified and subsequently modified by grafting lactide-chains onto the hydroxyl groups via ring opening polymerization with L-lactide. The structures and average molar masses of the lactide-grafted xylan polymers were characterised by NMR and SEC respectively. By varying the lactide-to-xylan feed ratio, graft polymers with different graft levels were synthesized. The degree of substitution of the hydroxyls in the xylan back-bone ranged from 0.7 to 1.7 with lactide side-chains having an average length of 1.2 to 2.5 lactide units. The side-chain length and degree of substitution influenced the hydrophobicity, thermal properties and tensile strength properties. A glass transition could be detected for lactide-grafted xylan polymers with lactide chains longer than 1.8 lactide units. Solution-cast thin films prepared from lactide-grafted xylans exhibited strong tensile strength and high modulus with decreasing strength and increasing elongation at break as the lactide chain length was increased.
Place, publisher, year, edition, pages
2012. Vol. 27, no 3, 518-524 p.
Hemicellulose, Xylan, Grafting, Lactide, Glass transition, Tensile strength
IdentifiersURN: urn:nbn:se:kth:diva-85778DOI: 10.3183/NPPRJ-2012-27-02-p518-524ISI: 000311020100001ScopusID: 2-s2.0-84865223617OAI: oai:DiVA.org:kth-85778DiVA: diva2:500106
QC 201212142012-02-132012-02-132012-12-14Bibliographically approved