Effect of thermo-vacuum modification on selected chemical, physical, and mechanical properties of Siberian larch (Larix sibirica L.) wood

The primary aim of this research was to investigate and evaluate the effects of thermo-vacuum modification through forced convection on selected chemical, physical, and mechanical characteristics of Siberian larch (Larix sibirica L.) wood. Larch wood boards were thermally-modified, using press-vacuum plant technology, for three hours at a temperature of 200 degrees C and a pressure of 350 mBar. In order to characterise the thermally-modified (TH) and unmodified (CTRL) wood samples, the extractives, lignin and holocellulose content, volumetric swellings, compression strength, and modulus of elasticity (MOE) were determined. Gas chromatographic-mass spectrometric (GC-MS) analysis revealed chemical compound changes as a result of the thermal modification process where some extractives became undetectable after treatment while some new extractives were detected. Thermally-modified larch wood exhibited lower volumetric swelling compared to the untreated samples. Markedly, thermally-modified larch wood had lower tendency to absorb moisture. In addition, thermally-treated wood had slightly higher compression strength parallel to the grain, which was 0.29% higher than that of unmodified samples. Meanwhile, a 7.6% reduction in MOE was recorded in the thermally-treated wood.

Automated summary

The primary aim of this research was to investigate and evaluate the effects of thermo-vacuum modification on the characteristics of Siberian larch wood. The results showed that the thermal modification process led to changes in chemical compounds in the wood samples, with some extractives disappearing and new ones being detected. The thermally-modified larch wood had lower volumetric swelling and moisture absorption compared to the untreated samples. The compression strength parallel to the grain was slightly higher in the thermally-treated wood, while the modulus of elasticity was reduced.