Studies of the degradation and protection of wood surfaces

Abstract

Large weight losses occurred in thin veneers of radiata pine (P. radiata) during natural weathering due mainly to loss of lignin and hemicelluloses. This was demonstrated by direct chemical analysis and by spectrocopic techniques. Treatment of veneers with dilute aqueous solutions of the recognized surface stabilizing compound chromium trioxide was found to dramatically restrict weight loss during weathering, but similar applications of ferric compound were less effective (Evans, Schmalzl 1989). In order to rationalize these protective effects FTIR internal reflectance spectroscopy was used to study chemical changes taking place at the wood surface upon treatment and during weathering. The spectra obtained provide direct evidence for the modification and stabilization of the lignin aromatic system with aqueous chromium trioxide and to a lesser extent with ferric salts. It is postulated that photostable lignin complexes are formed. The implications of these findings for the development of improved surface stabilizing compounds for wood are discussed briefly.

Impacts of impregnation with Imersol‐Aqua on the modulus of elasticity in bending

“…13 For determining the airdry density, the test samples with a dimension of 20 ϫ 30 ϫ 30 mm 3 were kept under the conditions of 20°C Ϯ 2°C and 65% Ϯ 5% relative humidity until they reached a stable weight. The weights were measured with an analytic scale of Ϯ0.01-g sensitivity.…”

“…14 :The samples with a dimension of 20 ϫ 20 ϫ 20 mm 3 were weighed and then oven dried at 103°C Ϯ 2°C till they reached a constant weight. Then, the samples were cooled in a desiccator containing calcium chloride (CaCl) and weighed with an analytic scale of 0.01-g sensitivity.…”

“…The samples with a dimension of 20 ϫ 20 ϫ 400 mm 3 were cut from the drafts having an average humidity of 12% according to TS EN (European Norm) 408. 15 The densities and humidity values of all test samples were measured before the impregnation process.…”

“…2 In case wood is not impregnated but only painted and varnished instead, the protection on the surfaces is limited to a maximum of two years. 3 It is reported that, in mines, as a result of the impregnation of the beech and spruce wood with watersoluble salts, the bending, tensile, and impact strength decreased a little, whereas compression strength increased. 4 In another research concerning the impregnation of pine, spruce, fir, beech and poplar woods with Antrasen, it was found that the compression strength increased by 6 -40% and the bending strength increased by 10 -22%.…”

Chemical Alterations of Pine Wood Lignin during Heat Sterilization

“…Unprotected wood that has been exposed to outdoor conditions undergoes a variety of degradation reactions caused by diverse environmental factors such as light, moisture, heat, oxygen, pollutants, pests, etc. (Evans et al 1992;Hon 1994;Teaca et al 2013). There are various ways to protect the wooden parts of buildings, e.g.…”