Lignosulfonate polymerization: Effect of cross-linking agents

✍ Scribed by A. M. Bialski; H. Bradford; N. G. Lewis; C. E. Luthe

• Publisher: John Wiley and Sons
• Year: 1986
• Tongue: English
• Weight: 547 KB
• Volume: 31
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1986.070310520

✦ Synopsis

Factors affecting the thermosetting properties of spray-or freeze-dried, ammonium-based spent sulfite liquor, a material rich in lignosulfonates, were investigated. It was found that purified lignosulfonates did not thermoset readily, unless either monomeric wood sugars or formaldehyde were present. Under the conditions employed, the monosaccharides were more effective than formaldehyde as thermoset accelerators. This may be due to the greater functionality of the intermediate decomposition products of the carbohydrates, which would create more reactive sites for intermolecular bonding with lignin. In contrast to previous findings, it was found that lignosulfonates (of mol wt > 10,000) underwent polymerization, and subsequent thermosetting, more rapidly than their lower molecular weight counterparts. This was established by HPLC size exclusion elution chromatography of each sample following thermal treatment. It was also observed that wood did not affect the rate of thermosetting.