Mechanical characterisation of fibres for engineered wood products: a scanning force microscopy study

Mechanical properties of individual wood fibres and the characterisation of the interaction between wood fibres and resins are of interest to the composite wood panel industry and others involved in the fabrication of engineered wood products. However, the size of such fibres typically a few millimetres in length, makes characterisation of their mechanical properties difficult. Gripping fibres is problematic, not to mention the measurement of meaningful load displacement data. Using a novel three point bend test technique, the Young’s moduli of single wood fibres were determined. Fibres were placed on a specially designed test rig and a scanning probe microscope was used to apply a load and to measure the deflection at the centre of each fibre. A model of the fibre was produced in order to facilitate data analysis. The technique proved to be feasible, resulting in an average Young’s modulus value of 24.4 GPa for Pinus Sylvestris softwood fibres. This compares well with other values in the literature, but there is scope for improvement in the methodology to lead to more accurate measurements