Effect of climatic conditions on the physico-mechanical properties of MDF boards

Four types of surface coating, on commercial MDF 19 mm thick panels, are used to study the behaviour of MDF panels under four different conditions of relative humidity. The behaviour of the panels is studied by means of the comparison between the initial and final (after conditioning) values of the Modulus of Rupture (MOR), Modulus of Elasticity (MOE), Internal Bonding (RTP), Equilibrium Moisture Content (HEH) and density. In some cases the evolution of some properties is monitorized during the conditioning treatment. Four different environmental conditions are considered, three of them constant (20º C/65 p. 100 rh, 20º C/90 p. 100 rh, 20º C/35 p. 100 rh) and one variable (20º C/35-90 p. 100 rh). Boards under a constant environment of 20ºC/90%rh used to exhibit a clear worse behaviour than under variable climate of 20º C/ 35-90 p. 100 rh. This general behaviour is just the opposite than the one exhibited by particleboards in a previous work.