Mechanical properties of spruce wood cell walls by nanoindentation
- First Online:
- 861 Downloads
In order to study the effects of structural variability, nanoindentation experiments were performed in Norway spruce cell walls with highly variable cellulose microfibril angle and lignin content. Contrary to hardness, which showed no statistically significant relationship with changing microfibril angle and lignin content, the elastic modulus of the secondary cell wall decreased significantly with increasing microfibril angle. While the elastic moduli of cell walls with large microfibril angle agreed well with published values, the elastic moduli of cell walls with small microfibril angle were clearly underestimated in nanoindentation measurements. Hardness measurements in the cell corner middle lamella allowed us to estimate the yield stress of the cell-wall matrix to be 0.34±0.16 GPa. Since the hardness of the secondary cell wall was statistically not different from the hardness of the cell corner middle lamella, irrespective of high variability in cellulose microfibril angle, it is proposed that compressive yielding of wood-cell walls is a matrix-dominated process.
Unable to display preview. Download preview PDF.
- 2.R.E. Mark: Cell Wall Mechanics of Tracheids (Yale University Press, New Haven 1967)Google Scholar
- 4.D. Fengel, G. Wegener: Wood. Chemistry, Ultrastructure, Reactions (De Gruyter, Berlin 1984)Google Scholar
- 6.D.H. Page, F. El-Hosseiny, K. Winkler, A.P.S. Lancaster: Tappi 60, 114 (1977)Google Scholar
- 16.T.E. Timell: Compression Wood in Gymnosperms (Springer, Berlin 1986)Google Scholar
- 24.D. Tabor: ‘Indentation Hardness and its Measurement: Some Cautionary Comments’. In: Microindentation Techniques in Science and Engineering, ed. by P.J. Blau, P.R. Lawn (American Society for Testing and Materials, Philadelphia 1986) pp. 129–159Google Scholar
- 32.R.M. Kellogg, C.B.R. Sastry, R.W. Wellwood: Wood Fiber Sci. 7, 170 (1975)Google Scholar
- 33.L. Salmén, A. De Ruvo: Wood Fibre Sci. 17, 336 (1985)Google Scholar
- 36.W. Gindl, T. Schöberl: Composites Part A, in print, available online, DOI: 10.1016/j.compositesa.2004.04.002Google Scholar