Effect of relative humidity on shear modulus of particleboard. The effect of relative humidity on the shear modulus of particleboard was presented in the paper. Panel specimens were conditioned at 55, 65, 75, 85 and 95% RH. The moisture content and shear modulus of particleboard were determined on these specimens by the twisted square piate method. The relationships between the shear modulus and the moisture content of particleboard and relative humidity were defined.
This paper presents the preliminary research results of a project whose main objective is to quantify the impact of formulations and technological parameters on formaldehyde content in and emission from particleboards produced using urea-formaldehyde resin with a low molar ratio of F/U. The formaldehyde content reduction is possible by using a resin with a molar ratio of F/U of 1.065 hardened with 3% solution of urea and ammonium nitrate or a resin with a molar ratio of F/U of 0.96 to which 3% urea was added. For these variants, reductions by 22% and 21% respectively of formaldehyde content in particleboards were obtained, while at the same time, strength properties that meet the requirements of the EN-312: 2011 standard for P2 particleboards were maintained.