Elastic Modulus, Thermal Expansion, and Pyrolysis Shrinkage of Norway Spruce Under High Temperature

Abstract The orthotropic and temperature-dependent nature of the mechanical properties wood is well recognized. However, past studies at elevated temperatures are either limited to below 200 °C or focus only on direction parallel grain. effect time-dependent pyrolysis during measurement often neglected. This paper presents a novel method for determining elastic modulus high thermal expansion coefficient in different directions via Dynamic Mechanical-Thermal Analyser (DMTA). allows drying, drying verification, one chamber, eliminating possibility moisture reabsorption from ambient air. repeatable measurements can be carried out up 325°C, adequate observing measurement. Results Norway Spruce provide data its response temperature range previously not explored widely, as direction. Time-dependent behaviour was observed shrinkage experiment, where above 250°C amount depends heating rate. At such temperature, moduli also shows time dependence, longer certain slightly increases measured modulus. Additionally, bilinear regression relationship between quantitatively good fit. Numerical simulation DMTA history chemical components mass losses show onset hemicellulose loss occurring around same time, while decomposition cellulose correlate with sudden moduli.