Dissolution of softwood kraft pulps by direct derivatization in lithium chloride/N,N-dimethylacetamide
2004 (English)In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 94, no 2, 424-431 p.Article in journal (Refereed) Published
A method for the characterization of the molar mass distributions (MMDs) of softwood kraft pulps dissolved in 0.5% lithium chloride (LiCl)/N,N-dimethylacetamide (DMAc) by size exclusion chromatography is presented. The method is based on derivatization with ethyl isocyanate and the dissolution of samples in 8% LiCl/DMAc. In this study, the derivatization of hardwood kraft pulps did not influence the MMD. In the case of softwood pulps, however, the derivatization decreased the proportion of the high-molecular-mass material and increased the proportion of the low-molecular-mass material, which resulted in a distribution similar to the MMD of a hardwood kraft pulp. The results suggest that associations between hemicellulose and cellulose in the softwood kraft pulp were ruptured during derivatization. This led to a more correct estimation of the MMD of derivatized softwood kraft pulps than obtained by the dissolution of nonderivatized samples. This new method offers several advantages over derivatization with phenyl isocyanate: a precipitation step is not necessary, it is possible to follow the lignin distribution in the samples, and the method allows very high levels of dissolution of softwood kraft pulps up to a kappa number of around 50.
Place, publisher, year, edition, pages
2004. Vol. 94, no 2, 424-431 p.
gel permeation chromatography (GPC) polysaccharides, molecular weight distribution/ molar mass distribution
Paper, Pulp and Fiber Technology
IdentifiersURN: urn:nbn:se:kth:diva-92179DOI: 10.1002/app.20697ISI: 000223599200003OAI: oai:DiVA.org:kth-92179DiVA: diva2:512565
QC 201203282012-03-282012-03-282012-03-28Bibliographically approved