MFA and acoustic properties in spruce (Hori et al, 2002)

The influence of the micro- and mesoscopic structure of wood cell walls on the acoustic properties of softwood was investigated in a synchrotron X-ray microbeam diffraction experiment with particular attention to the seasonal differences in crystallographic features. A multiple regression analysis was performed for data from 12 different softwood species in order to determine the dependence of longitudinal relative Young’s modulus (E/ρ) and loss tangent (tan δ) on seasonal cellulose microfibril angles (MFAs), crystal width of cellulose microfibrils etc. We conclude that a low MFA in both latewood and earlywood yields high E/ρ and low tan δ, which is an attribute of wood used as violin or piano soundboards. Among the softwood species we characterized Sitka spruce best fits this criterion.

(a) Optical sample images and diffraction diagrams. (b) Azimuthal distribution plot from (004) plane. Solid line is direction of cell axes. MFA could be obtained from degree between cell axes and dash line. (c) Radial integration from diffraction. It was divided into four peaks (1-10, 110, 200, amorphous)