Retardant Poplar Veneer And Plywood Sorption

The chemical and physical properties of flame retardant determine that there will be some disadvantages when it is dealing with fire-retardant plywood and veneer. This study is the deep research for its advangtages and deficiencies.By the experimental sduty of the veneer's several properties such as:flame veneer drug loading, moisture absorption, dimensional stability, veneer wood color, environmental scanning electron microscopy and Fourier transform infrared and so on, this paper analyse the effects and the reason of flame retardant on the veneer of the physical and chemical properties. Based on the orthogonal experiment, this paper discusses the production process of flame retardant plywood, and picks up the optimum process. The main conclusions are as followed:(1) The concentration and temperature of fire retardant have positive influnces for drug loading of the veneer.(2) Under the same conditions of humidity, the moisture absorption rate and the rate changes of veneer's size of the wood by the fire retardant treatment was significantly higher than that of the untreated. There is a higer moisture absorption rate with the higher concentration when the humidity is the same. When the humidity is different, the high humidity will result in the high moisture absorption rate. The rule of the size changes of the moisture absorpted flame veneer is: thicknessl>length. The coulour of the wood will become yellow and dark when the wood is treated by flame retardant and moisture absorption.Wood catheter line attached to a small number of transparent particles, mainly distribution in the surface, the absorption peak decreased with the flame retardant concentration increased in the wave number of 1741.59 cm'(3) When prepared plywood is manufactured by BL-environmental-friendly flame retardant, the process of the veneer impregnation is followed:40%of flame retardant concentration, soaking temperature of 60℃,60min soaking time. The process of the hot pressing technology is:130℃hot pressing temperature,1.2MPa hot pressing pressure and 45s/mm hot pressing time. The oxygen index of flame-retardant plywood suppression with this process can reach to 63.2%, formaldehyde emission of only 0.10mg/L, the bonding strength reached 1.20 MPa, water content was 7.3%, and four indicators are in line with the requirements of appropriate national standards.(4) When the retardant plywood is treated with moisture adsorption, it will show the follow rules: with the air humidity increases, the oxygen index will be relatively lower, formaldehyde emission did not change significantly, and the bonding strength will be significantly reduced.