All correspondence regarding this article should be directed to the second author. This study was financially supported by the National Science Foundation, Washington, D.C., under grant no. PFR 79-13135. Valuable advice by Drs. P. L. Hall, J. McGrath, and M. Ogliaruso, all from the Chemistry Department of Virginia Tech, is acknowledged with gratitude.
Engineering plastics from lignin. I. Synthesis of hydroxypropyl lignin
Article first published online: 9 MAR 2003
Copyright © 1984 John Wiley & Sons, Inc.
Journal of Applied Polymer Science
Volume 29, Issue 4, pages 1111–1123, April 1984
How to Cite
Wu, L. C.-F. and Glasser, W. G. (1984), Engineering plastics from lignin. I. Synthesis of hydroxypropyl lignin. J. Appl. Polym. Sci., 29: 1111–1123. doi: 10.1002/app.1984.070290408
- Issue published online: 9 MAR 2003
- Article first published online: 9 MAR 2003
- Manuscript Accepted: 24 SEP 1983
- Manuscript Received: 3 JUN 1983
Hydroxypropylation of lignin in a batch reactor under alkaline conditions at 180°C was studied using propylene oxide (PO) by itself, and PO in combination with several ligninlike model compounds and with kraft lignin. While the PO homopolymerization rate increased rapidly at temperatures above 85°C, and was too fast to be determined accurately at 180°C, the addition of model compounds and lignin was found to delay homopolymerization in relation to the presence of ionizable functional groups. The observations are consistent with a reaction mechanism involving first order kinetics with regard to each alkoxide and PO concentrations. Where the reaction rates toward PO increase with increasing pKa values, the reaction sequence proceeds in the order of declining basicity. Thus lignins with high acidity were found to be subject to greater degrees of modification than those with more neutral character. This explains the earlier observed beneficial effect of lignin carboxylation on the properties of lignin–PO reaction mixtures.