Studying thermal conductivity of wood at cell wall level by scanning thermal microscopy (SThM)

Abstract Local variability in the thermal conductivity of the cell wall of beech wood fibers was studied by means of scanning thermal microscopy (SThM). In the cross section, the thermal conductivity of the secondary cell wall was essentially higher than that of the compound middle lamella (CML). In sections parallel to the cell axis, the overall conductivity of the S1 layer was lower than that of the secondary cell wall, but the S2 layer and the CML showed similar conductivities. This is attributed to the orientation of the cellulose microfibrils playing a key role in the observed anisotropies concerning the thermal conductivity. The deviating thermal conductivities on different sections are attributed to the depth effect of the thermal scanning. SThM proves to be a technique with considerable potential for wood research.