Effect of liquid nitrogen application on retention and mechanical properties of oak wood

Wood is a natural material widely utilized in the forest industry and furniture sector, valued for its aesthetics and durability. Various methods have been developed to extend its service life and protect it against deterioration. In this study, liquid nitrogen treatment was applied to increase retention levels, and the effects of retention and impregnation agents on the mechanical properties of oak wood were examined. Oak (Quercus robur), a species known for its low permeability and difficulty in impregnation, was selected as test samples. The samples were exposed to liquid nitrogen for 15 minutes, 90 minutes, and 6 hours, and subsequently impregnated with Tanalith-E, Imersol Aqua, Diammonium Sulphate, and Borax using brush application, short- and long-term immersion, and pressure methods. Retention levels were determined, and mechanical performance was assessed through compression parallel to the fibers and dynamic bending (impact) resistance tests. The maximum retention value was found to be 4.212 kg/m³ in the long-term immersion method with Borax and a 519% increase in retention rate was obtained. The results showed that liquid nitrogen application increased retention in oak wood and due to this increase, changes in compressive strength and impact strength were observed parallel to the fibers.