The relation between indentation modulus, microfibril angle, and elastic properties of wood cell walls

• Published in: Composites. Part A, Applied science and manufacturing Applied science and manufacturing, 2011, Vol.42 (6), p.677-685
• Main Authors: Jäger, A., Bader, Th, Hofstetter, K., Eberhardsteiner, J.
• Format: Article
• Language: English
• Subjects: A. Wood; Anisotropy; Applied sciences; B. Mechanical properties; Byggteknik; C. Analytical modeling; cell wall components; cell walls; Civil engineering; Elastic constants; Exact sciences and technology; Forestry and Wood Technology; Indentation; materials; mechanical properties; Micrometers; Modulus of elasticity; Nanoindentation; Polymer industry, paints, wood; Properties and testing; Skog och träteknik; testing; Walls; Wood; wood properties; Wood. Paper. Non wovens
• ISSN: 1359-835X; 1878-5840; 1878-5840
• DOI: 10.1016/j.compositesa.2011.02.007

Nanoindentation is a well known tool for identification of mechanical properties at the micrometer scale of materials. When applied to study wood cell walls the commonly used isotropic indentation theory is not applicable. In this study, anisotropic nanoindentation theory was employed for analyzing nanoindentation test results on wood cell walls. The influence of elastic stiffness components, microfibril angle, and cell wall composition on the indentation modulus was studied. The indentation modulus was found to depend on longitudinal, transverse, and shear modulus to a similar extent. A significant influence of the microfibril angle on the indentation modulus was observed and discussed with respect to experimental scatter and sample preparation. It is concluded, that application of anisotropic nanoindentation theory provides a tool for quantitative instead of qualitative investigation of wood cell walls, with the goal of identifying all elastic properties of the transversely isotropic cell wall from nanoindentation tests.