Prediction of transport properties of wood below the fiber saturation point – A multiscale homogenization approach and its experimental validation: Part I: Thermal conductivity

This two-part paper covers the development and validation of a multiscale homogenization model for macroscopic transport properties of wood. The starting point is the intrinsic structural hierarchy of wood, which is accounted for by several homogenization steps. Starting on a length scale of a few nanometers the model ends up with macroscopic properties by including the morphology of the intermediate hierarchical levels. In this first part this is done for thermal conductivity, based on a six-level homogenization scheme. The used homogenization technique is continuum micromechanics in terms of self-consistent and Mori-Tanaka schemes. Model validation rests on statistically and physically independent experiments: the macroscopic thermal conductivity values predicted by the multiscale homogenization model on the basis of tissue-independent (universal) phase conductivity properties of hemicellulose, cellulose, lignin, and water (input data set I) for tissue-specific data (input data set II) are compared to corresponding experimentally determined tissue-specific conductivity values (experimental data set).