Influence of thermal softening and degradation on the radial compression behavior of wet spruce

Thermal softening and degradation of wood are important factors in wood processing. In this investigation, the influence of temperature - between 0 and 200 degrees C - on the mechanical behavior of wet spruce subjected to large radial compression was studied. The yield stress of wet spruce dropped by slightly less than one tenth between 0 and 200 degrees C. The glass transition of lignin was detected accurately by measuring the yield stress. A thermal degradation process was observed between 150 and 200 degrees C. The shapes of the normalized stress-strain curves were similar at different temperatures.