| Salix discolor, which is a new kind of fast-growing tree in China,has many good properties,such as short growth cycle, high adaptability and high transplanting survival rate, and it determines the potential of its application in wood industry. The character of Salix discolor was studied in this paper, and the effects of different technological conditions on the physical-mechanical properties of soybean-based and UF-based Salix discolor particleboard were analyzed; The effect of bark addition on the formaldehyde emission of UF-based Salix discolor particleboard was studied. The strain distribution of Salix discolor-adhesive interface was measured by digital correlation method(DSCM) and the reaction mechanism of adhesive and Salix discolor were studied by ATR-FTIR. The comparison of Salix discolor and Poplar was studied in this paper.The results of the study on the character of Salix discolor showed that the shrinkage rate and differential shrinkage rate of Salix discolor were lower than Poplar, which indicated that the dimension stability of Salix discolor was better. The density of Salix discolor was lower than Poplar. The results of the study on chemical components showed that the contents of holocellulose and celluloseacid of Sailx discolor were lower than Poplar. Cellulose is the main component to form the strength of wood-based panel. The content of hemicellulose and accumulator insoluble lignin of Salix discolor were basically the same as Poplar. The extractive content of Salix discolor was higher than Poplar; The pH value of Salix discolor was higher than Poplar, which will extent the curing time of UF resin. The result of the study on wettabillty showed that the wettability of Salix discolor xylem was better than bark, and worth than Poplar xylem.Bark addition, density, adhesive content and water repellent addition are main factors to influence the properties of Salix discolor particleboard, designing single factor experiment for these factors, manufacturing particleboard with UF, and testing the properties of particleboard in the experimental condition. An all-round consideration of factors of the costs and the properties of particleboard was made to conclude that when the bark addition was 10%, density was0.65g/cm3, adhesive content was 12% and water repellent addition was 10%, the physical-mechanical properties of the particleboard exceeded national standards. Under the same technological conditions, the physical-mechanical properties of Poplar particleboard were better than Salix discolor particleboard. The results of formaldehyde emission of UF-based Salix discolor particleboard showed that the formaldehyde emission increased with the increasing of bark addition, and the formaldehyde emission of Salix discolor particleboard is higher than Poplar particleboard under the same Under the same technological conditions.The effects of adhesive content on the properties of soybean adhesive-based Salix discolor particleboard was analyzed. The results showed that the properties of particleboard werepromoted as the adhesive content increased. The results showed that 12% was the most appropriate choice for the adhesive content. Under the condition of same adhesive content, the physical-mechanical properties of soybean adhesive-based Poplar particleboard were better than Salix discolor particleboard.The results of ATR-FTIR showed that xylem and bark had the same functional groups, but there were differences in content. The —OH group on the UF-based Salix discolor particleboard decreased sharply compared to Salix discolor. The functional groups of cellulose, hemicellulose and lignin had reaction with UF and soybean adhesive.The results of DSCM showed that the max shear strain occurred at the ends of glue interface when loading, and the ends of glue interface were fractured firstly; The shear strain increased linearly as loading before damage, and increased sharply approaching damage; The max shear strain of UF-salix discolor interface is lower than that of soybean adhesive-salix discolor interface under the same load, and salix discolor glued by UF need larger load to be damaged. |
