The effects of urea-formaldehyde resin and paraffin contents on fluid flow (air and water) and physico-mechanical properties of medium-density fibreboards

Abstract

ABSTRACT The effects of different urea-formaldehyde (UF) resin and paraffin contents on the physical and mechanical properties of medium-density fibreboards (MDF), and their relationship with air and liquid permeability were investigated. The MDF panels were fabricated with three UF resin and three paraffin contents, based on the dry fibres. The physical and mechanical properties of the MDF panels were determined in accordance with the ASTM D1037-99 standard. The highest (3.7 × 10−13 m3 m−1) and lowest (1.2 × 10−13 m3 m−1) air permeability values were found in the panels manufactured with the lowest resin and paraffin contents and the highest resin and paraffin contents, respectively. A significant inverse relationship was found between the permeation of both fluids (air and water) through MDF panels versus resin and paraffin contents. Higher UF-resin contents made wood fibres be stuck more strongly together, limiting the flow of fluids. The water-repellent property of paraffin contributed to the decrease in liquid permeability as paraffin content was increased. Markedly, the coefficients of determination of the regression models between permeability and physical properties were found significant. The mechanical properties also showed significant regression with air permeability. It was concluded that air permeability can be considered a reliable property to predict water absorption behaviour in MDF.