Physical properties of Portuguese pinewood chemically modified

Abstract

Maritime Pine softwood has low dimensional stability. Chemical modification is the easiest way to improve technological features of the softwood into a material with enhanced and less varied properties. In this work, physical properties of modified wood using four methods of modification were studied. Pure sapwood of the Maritime pine species (Pinus pinaster Ait.) was submitted at different chemical modification processes: 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU), N-methylol melamine (MMF), tetra-alkoxysilane (TEOS) and wax (amid WA and montan/lignite wax WL). The following physical properties were assessed experimentally: density and weight percent gain (WP), equilibrium moisture content (EMC), isotherms curves, anti-swelling efficiency (ASE), swelling strain and swelling coefficient. Significant changes in the material properties took place. All modification processes increased the density of modified wood in different extent: Modification with cell wall reaction (DMDHEU and MMF resin) were the most effective methods to achieve high dimensional stability (ASE) in parallel with low equilibrium moisture content (EMC). The lumen fill modification (TEOS and wax) had no effect in to different physical properties.