Changes in chemical and optical properties of silver fir (Abies alba L.) wood due to thermal treatment

Alterations in the chemical composition of silver fir wood (Abies alba L.) during thermal treatment were investigated. The mass loss, extractives, saccharides, and lignin were determined. In both untreated and heat-treated wood, extractives were determined according to ASTM D1107-96, lignin content according to ASTM D1106-96, and saccharides by high-performance liquid chromatography. During the thermal treatment, mass loss and the chemical composition of the wood were found to change. The extractives content decreased up to 200 degrees C, and then increased at higher temperatures. The mass loss increased with increasing temperature and time of thermal treatment. A relative increase in lignin content and a decrease in saccharides were observed. The color of the wood was stable at temperatures up to 150 degrees C when treated up to 1h. A change in color significantly depends on thermal energy intake above that level. Saccharides, color coordinates L* and b*, lignin, mass loss, temperature, and color change E* strongly vary together. These investigated properties of fir wood set out the boundaries for high-temperature treatment and show potential for utilization of this species.