LONGITUDINAL HARDNESS AND YOUNGS MODULUS OF SPRUCE TRACHEID SECONDARYWALLS USING NANOINDENTATION TECHNIQUE

Using a mechanical properties microprobe, measurements of hardness and elastic modulus of tracheid walls in the longitudinal direction of sp ruce wood were obtained by continuously measuring force and displaceme nt as a diamond indenter impressed a cell wall. Maximum mechanical pro perties were found at the edges of the walls of angular shaped trachei ds. Both the hardness and elastic modulus of latewood cell walls were higher than cell walls in the earlywood. The high spatial resolution o f this new concept of mechanical testing allows a direct comparison wi th ultrastructural and microchemical parameters of lignified cells whi ch opens a wider area of applications for the understanding of intrins ic wood properties.