Probing the macromolecular structure of wood and pulps with proton spin-lattice relaxation time measurements in the solid state

✍ Scribed by Dimitris S. Argyropoulos; Frederick G. Morin

• Publisher: Springer
• Year: 1995
• Tongue: English
• Weight: 699 KB
• Volume: 29
• Category: Article
• ISSN: 0043-7719
• DOI: 10.1007/bf00196929

✦ Synopsis

By measuring the proton spin-lattice relaxation times (T~) in the solid state, for a series of progressively sulphonated and methylated black spruce pulps, the molecular mobilities of carbohydrates and lignin have been evaluated as a function of chemical treatment. These measurements were made possible only after the paramagnetic metal ion impurities were removed from the samples. For untreated wood the proton T, values of carbohydrates and lignin were virtually undistinguishable, irrespective of the applied magnetic field strength. The introduction of sodium salts of carboxylic and sulphonic acid groups in softwood pulps and the introduction of methoxyl groups, seem to very significantly increase the molecular mobilities of carbohydrates and lignin. The opposite was true when calcium were the counterions of the acidic groups. These observations have been attributed to the disruption of associative lignin-carbohydrate hydrogen bonding interactions otherwise operating within untreated wood.