Moisture adsorption of glucomannan and xylan hemicelluloses
- 460 Downloads
Wood and wood materials are highly sensitive to moisture in the environment. To a large extent this relates to the hygroscopicity of wood hemicelluloses. In order to increase our understanding of the effects of moisture sorption of the major wood hemicelluloses, glucomannan and xylan, model experiments using films of amorphous konjak glucomannan and rye arabinoxylan were conducted. Moisture-induced expansion and stiffness softening were characterized using dynamic mechanical testing. Both hemicelluloses showed a threshold around 5 % of moisture content above which swelling increased whereas the modulus decreased by more than 70 %. FTIR spectra, using H2O and D2O, indicated that even at high RH about 15 % of the hydroxyl groups were not accessible to hydrogen exchange by D2O. For xylan both hydroxyl groups were found to exchange in the same manner while for the glucomannan the O(6)H group seemed to be the most accessible.
KeywordsDeuterium Glucomannan Hemicellulose Sorption Swelling Weakening Xylan
Wallenberg Wood Science Centre is gratefully acknowledged for financial support.
- Berthold J, Rinaudo M, Salmeń L (1996) Association of water to polar groups; estimates by an adsorption model for ligno-cellulosic materials. In: Colloids and surfaces A: physicochemical and engineering aspects. pp 117–129Google Scholar
- Olsson A-M, Salmén L (2003) The softening behavior of hemicelluloses related to moisture. In: Gatenholm P, Tenkanen M (eds) Hemicelluloses: science and Technology. Amer Chemical SocietyGoogle Scholar
- Rissanen JV, Gre H, Willfo S, et al. (2014) Spruce hemicellulose for chemicals using aqueous extraction: kinetics, mass transfer, and modelingGoogle Scholar
- Salmén L, Fellers C (1989) The nature of volume hydroexpansivity of paper. J Pulp Pap Sci 15:J63–J65Google Scholar