Cell wall porosity in norway spruce wood as affected by high-temperature drying

In this study, pore size distribution in wood after high-temperature drying followed by rewetting was investigated by differential scanning calorimetry. Nonfreezing water content of wood was lower than previously indicated considering the effect of phase change on specific heat capacity of water. High-temperature drying appeared to close cavities of the largest size in earlywood, particularly with increasing drying temperature and time. Pore closure by irreversible hydrogen bonding dominated the eventual creation of cavities by degradation of wood structural components. Stress relaxation within wood elements, favored by slow high-temperature drying, decreased the extent of drying microcracks in earlywood, manifested in lower nonfreezing water content.