Study of chemical modification of alkaline lignin by the glyoxalation reaction
dc.contributor.author
dc.date.accessioned
2013-04-02T11:40:21Z
dc.date.available
2013-04-02T11:40:21Z
dc.date.issued
2011
dc.identifier.issn
1930-2126
dc.identifier.uri
dc.description.abstract
In this study, glyoxalated alkaline lignins with a non-volatile and non-toxic aldehyde, which can be obtained from several natural resources, namely glyoxal, were prepared and characterized for its use in wood adhesives. The preparation method consisted of the reaction of lignin with glyoxal under an alkaline medium. The influence of reaction conditions such as the molar ratio of sodium hydroxide-to-lignin and reaction time were studied relative to the properties of the prepared adducts. The analytical techniques used were FTIR and 1H-NMR spectroscopies, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Results from both the FTIR and 1H-NMR spectroscopies showed that the amount of introduced aliphatic hydroxyl groups onto the lignin molecule increased with increasing reaction time and reached a maximum value at 10 h, and after they began to decrease. The molecular weights remained unchanged until 10 h of reaction time, and then started to increase, possibly due to the repolymerization reactions. DSC analysis showed that the glass transition temperature (Tg) decreased with the introduction of glyoxal onto the lignin molecule due to the increase in free volume of the lignin molecules. TGA analysis showed that the thermal stability of glyoxalated lignin is not influenced and remained suitable for wood adhesives. Compared to the original lignin, the improved lignin is reactive and a suitable raw material for adhesive formula
dc.format.mimetype
application/pdf
dc.language.iso
eng
dc.publisher
North Carolina State University
dc.relation.ispartof
© BioResources, 2011, vol. 6, núm. 4, p. 4523-4536
dc.relation.ispartofseries
Articles publicats (D-EQATA)
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Tots els drets reservats
dc.title
Study of chemical modification of alkaline lignin by the glyoxalation reaction
dc.type
info:eu-repo/semantics/article
dc.rights.accessRights
info:eu-repo/semantics/openAccess
dc.embargo.terms
Cap
dc.type.version
info:eu-repo/semantics/publishedVersion