Research On The Rice Straw Board Glued By Different Adhesives

Because of the severe contradiction of wood supply and demand,using the residues from agriculture becomes an issue that is increasingly important and urgent.Rice straw is one of the richest kinds of agricultural straw in China. It is widely distributed in China. Using rice straw as the raw materials for the wood-based panels have economical environmental and social benefiLGlue is an important factor affecting the quality of the board. This article selects the following factors such as hot-pressing temperature, hot-pressing time, density, the MC of rice straw etc. as the key factors to study the quality of the rice straw board glued by different adhesives.Because of the high wax ash and silica in the surface of the rice straw, it is difficult for UF to glue the rice straw board. Using the PF as the adhesive can improve the quality of the rice straw board, but the IB(intemal bond strength) and TS(thickness swelling of the board) are still very low. So the rice straw board glued by the UF and PF can't meet the national standards.MDI can react with rice straw , so MDI rice straw board has higher quality than the UF and PF rice straw board.The most important factor that affects the PF rice straw board is the hot-pressing temperature. With temperature increased, the quality of the rice straw board can be improved.The most appropriate condition for the MDI rice straw board is, resin content:7%, density:0.8g/cm3, hot-pressing temperature:150℃, hot-pressing time:20~24s/mm, the MC of the rice straw: 11%. Under the above conditions, the quality of the rice straw board can meet the national standard.When mixing the MDI and PF,adding the MDI first has higher IB (internal bond strength) and TS(thickness swelling of the board) than adding the UF first.And mixing the alcohol soluable PF and MDI is better than the water soluable PF.The reacting status of different adhesives is studied through the thermal analysis. The result shows that the MDI can react with the PF.To produce the rice straw board ,the product line should be reformed according to the character of the rice straw.