Effects of different accelerated aging modes on the mechanical properties, color and microstructure of wood

This research experimentally investigated the mechanical properties, color and microstructure of wood materials based on three accelerated aging modes. The moisture content, density, tension properties, compression properties, bending properties, shear properties, color, chemical composition and microstructure of the aged woods were studied. The density was reduced by 24–29 % within accelerated aging. The shear properties decreased the most (nearly 50 %), followed by the tensile and compressive properties, and the bending properties decreased the least (20–30 %). Lightness changed significantly during accelerated aging, which was the main reason affecting the color differences. The degradation of hemicellulose was the most (23–33 %), followed by lignin, while that of the cellulose was the least (about 5 %). Accelerated aging modes primarily influenced the degrees of the crystallinity, rather than altering the crystalline structures. The swelling of the wood particles and the degradation of the cellulose microfibril revealed by the microstructure characterized the reductions in mechanical properties. The CSA 2-h boil mode can be used as the accelerated aging mode for wood materials, while the other two accelerated aging modes had a similar aging effect with a slight extent.