Study On The Properties Of Salix Discolor And Its Plywood Made By Soybean Protein Adhesives

Salix discolor has many advantages, such as grown last?strong salt resistance? material quality and high density planting, In addition,it is easy to grow and has huge economic benefits, so it is praised as a fast-growing green Banks. For the above reason, we considered using Salix discolor to manufacturing plywood to meet the needs of the consumers as far as possible. Environmental problem is one of the most noticeable problems at present. Similarly, the formaldehyde in man-made board adhesion has become increasingly serious. The glue this study uses is pollution-free, zero-formaldehyde emission of soybean protein adhesives. First of all, making a systematic research the fiber morphology, chemical composition and physical and mechanical properties of the 4 years and 5 years Salix discolor, on the basis of above analysis,researching how hot pressing pressure, hot pressing time, amount of glue, veneer thickness and the old of the Salix discolor to affect the performance of the plywood, then determining the proper plywood production process parameters. In addition, the Salix discolor mold color and the permeability of the glue on the surface of the veneer were be also researched In the final, illustrating that the Salix discolor can be used in wood-based industry as a new raw material.The results of the characteristics of the raw material for Salix discolor showed that the fiber length of four years and five years Salix discolor belongs to the medium and short fiber. The wall of the cavity ratio shows that Salix discolor was very good fiber material. The comprehensive analysis of hot and cold water extract, benzyl alcohol extract and 1% NaOH extract, ensemble cellulose, cellulose, acid insoluble lignin content of Salix discolor in different year concluded that the chemical composition of Salix discolor was close to Populus euramevicana cv, so it can be used as industrial raw materials in wood-based industry. The Contact Angle value of the distilled water, urea formaldehyde resin adhesive and soybean protein adhesives on the veneer elastic surface indicated that the wettability of soybean protein adhesives was the worst.The physical mechanical properties of Salix discolor was analyzed The results showed that the basic density, air dry density, oven dry density of four years and five years Salix discolor were near to the juvenile wood of Chinese fir, so it was suitable for plywood production. In addition, the Air dry difference shrinkage and the All dried difference shrinkage of Salix discolor were lower than Poplar, which indicated that the dimension stability of Salix discolor was better, that also means Salix discolor as raw materials for the wood-based industry produced products have good stability and it is hard to out of shape. Moreover, the bending strength of Salix discolor in five years was more than it in four years, but they were all lower than Poplar.Plate performance test results showed that glue content, hot-pressing pressure and hot pressing time have an impact on the bond strength of bamboo willow plywood, considering the production cost, compression ratio, production efficiency and other factors, the optimum hot-pressing parameters for this test are hot pressing time of 80 s/mm, two- sided glue quantity is 400 g/m2, hot pressing pressure is 0.7 MPa. Use the same optimum parameters we got to produced plywood of different year, among those plywood, the bond strength of Salix discolor of five years was better than that of four years.Salix discolor of the same year, the bond strength of plywood which veneers'thickness are 2 mm was better than the plywood which veneers'thickness are 1.2 mm.The research results of Salix discolor moldy discoloration indicated that the extract content of Salix discolor which color was less than the unchanged. What is more, the bending strength of the changed was also lower than the material does not change color. Infrared spectrum (FTIR) analysis showed that mould made the chemical composition of Salix discolor be changed, and cellulose and hemicellulose was degraded, but lignin content change little.The results of the permeability of glue showed that in the process of curing at 120?, the soybean protein adhesive have chemical reaction and form crosslinking.Scanning electron microscopy showed that the combination interface of soybean protein adhesives and veneer, the glue was pressed into the free space of wood cell, filled it and connected to the bond line. The soybean protein adhesives is easier to penetrate the veneer of 1.2 mm thick.XPS analysis results showed that:after hot pressing, C4 was appear on the surface of Salix discolor veneer, that meant high temperature hot pressing made the surface of Salix discolor produce organic acids, which was disadvantageous to the bonding process of alkali soybean protein adhesives and veneer.