The Study On Emission Law Of Formaldehyde From Wood-based Panels

Abstract:Four common wood-based panels were selected as research subjects and experiments and model analysis were conducted. Measurements of formaldehyde emission from four boards were obtained using a closed environment chamber at different temperatures and loading degrees. The physical emission model was optimized, a method for calculation of emission parameters of physical model was proposed, and also the relationship of temperature and emission parameters was studied. The grey model was used for the formaldehyde emission, the contribution level of temperature and loading degree influencing the concentration in different time was analyzed by grey relativity analysis method. The main conclusions are as follow:(1) The influence of temperature and loading degree to formaldehyde emission from wood-based panels:The increased of both temperature and loading degree can contribute to the concentration. Higher temperatures facilitated formaldehyde emission from wood-based panels; total emissions increase10～30%with a temperature increased of5degrees Centigrade, while total formaldehyde emissions from unit volume panel decreased at higher loading degrees.(2) Calculation of the emission parameters:The physical model was optimized. The initial mobile concentration, Cm,0, the diffusion coefficient, Dm and the partition coefficient, K, were calculated by using the emission process and equilibrium concentration in the closed environment chamber at a series of loading degrees and temperatures.(3) The relationship of temperature and emission parameters:Of four boards, Cm,0and Dm increased with temperature increased, while K decreased with temperature increased. For a same temperature, the influence of K and Cm,0to the emission of formaldehyde increase with time. The influence of Dm to plywood and density board first increased and then decreased, but to block board and laminate flooring, it decreased with time. For same board, the chamber concentration was most sensitive to Cm,0, and less sensitive to the partition coefficient, K and the diffusion coefficient, Dm.(4) Grey relativity analysis:The influence of temperature and loading degree to the emission concentration of plywood and laminate flooring did not change with time, and the incidence of loading degree was bigger than the temperature’s. The influence of temperature to density board first increased and then decreased, while the loading degree’s kept steady, but incidence of temperature was bigger. The influence of loading degree to block board first increased and then decreased, while temperature’s kept steady, but incidence of loading degree was bigger. For the four boards, the order of the incidence of temperature:density board>plywood> block board> laminate flooring, while the loading degree had a opposite order.(5)Comparison of grey models:Mostly the model GM (1,1) and DGM (1,1) had lager model accuracy for plywood, density board and block board, and can be used for simulation and forecast, while the model SCGM (1,1) only has accuracy for laminate flooring. Also the model SCGM (1,1) was not suitable for forecasting formaldehyde emits from any panel. For a same board, grey models had higher accuracy at middle emission time.