Low Density Wood Impregnation with Water-Repellent Organosilicic Compounds

Abstract

Many protective treatments for low density wood are applied by impregnationto give water-repellency and to control pathologies that usually have this substrate.The properties of Araucaria angustifolia , chemically modified by impregnationwith methyltriethoxysilane, n-octyltriethoxysilane and mixtures ofboth in several ratios, were investigated to achieve mainly high dimensionalstability, low capillary water absorption as well as satisfactory water vaporpermeability. The aforementioned impregnants produce the wood chemicalmodification, involving the reaction of hydroxyl groups of the wood with thehydrolysis products of alcoxysilanes. It is concluded that the organosiliconpolymers allow improving important characteristics of wood: 1) the non-occlusivecoating keeps the water vapor permeability unaltered; 2) the alkoxysilane type definesthe hydrophobicity and the continuity of coating formed on the porewall and finally; 3) the polymeric structure formed after finishing sol-gelprocess incises both on the capillary water absorption and the dimensionalstability. In addition, the studied treatments have the advantage of allowingthat the water vapor, which permeates through the organosilicon coatingplaced on cell wall, can exit by hydrophobic repulsion and thus, prevent faultsappearance generated by the condensed water inside of wood.