Sorption Behaviour and Dimensional Changes of Wood-Coating Composites
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Mari de Meijer
Summary
The moisture related properties of wood-coating composites have been studied to evaluate the influence of coating penetration on the protection of wood against moisture. Pine sapwood samples were vacuum-impregnated with 7 pigmented and unpigmented coatings, both water and solvent borne. The retention and void filling of the coating have been determined. After drying, the samples were exposed to relative humidities between 33 and 98 % and to liquid water and equilibrium moisture content and dimensional changes were measured. The rate of swelling and moisture sorption has been measured, the latter was also used to calculate diffusion coefficients. The sorption isotherms were analysed by the Hailwood-Horrobin equation. In order to obtain additional information on the hygroscopicity of coatings, similar measurement were made on free coating films.
The void filling of wood with coating material has the strongest impact on the uptake of liquid water. A limited reduction was observed for the equilibrium moisture content, the diffusion coefficient during adsorption and the rate of dimensional change. No influence on the equilibrium swelling have been found but the shrinkage during desorption was however often slightly increased for the wood-coating composites.
The limited impact of the penetrated coating on moisture related properties can to a large extent be explained by the low void filling after drying (20–60%) and the relatively high moisture sorption and swelling of the coating film itself. In general, it can be concluded that the moisture protection of penetrated coating material is low in comparison to coating applied as a film on the surface of wood.
Copyright © 1999 by Walter de Gruyter GmbH & Co. KG
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- Literature Reports
Articles in the same Issue
- The Significance of Accelerated Laboratory Testing Methods Determining the Natural Durability of Wood
- The Thermomechanical Behaviour of Wood Subject to Fungal Decay
- Fixation of Chromium in Wood from Trivalent Chromium Salt Solutions
- Spatial Distribution of Metal Ions in Spruce Wood by Synchrotron Radiation Microbeam X-Ray Fluorescence Analysis
- Chemical Composition of Lipophilic Extractives from Eucalyptus globulus Labill. Wood
- Antifungal Compounds in the Ethyl Acetate Soluble Fraction of the Extractives of Taiwania (Taiwania cryptomerioides Hayata) Heartwood
- Efficacy of Pinosylvins against White-Rot and Brown-Rot Fungi
- Investigations into Laccase-Mediator Delignification of Kraft Pulps
- Cell-Wall-Associated Oxidases from the Lignifying Xylem of Angiosperms and Gymnosperms: Monolignol Oxidation
- Atmospheric Acetic Acid Pulping of Rice Straw IV: Physico-Chemical Characterization of Acetic Acid Lignins from Rice Straw and Woods. Part 1. Physical Characteristics
- Lignin-Polyphenol Interaction in Azobe (Lophira alata) Heartwood. A Study on Milled Wood Lignin (MWL) and Klason Residues
- Electrospray Ionization Mass Spectrometry as a Tool for Lignins Molecular Weight and Structural Characterisation
- Determination of Phenolic Hydroxyl Groups in Lignin by Combined Use of 1H NMR and UV Spectroscopy
- The Effective Diffusion Coefficient and Mass Transfer Coefficient of Nordic Softwoods as Calculated from Direct Drying Experiments
- Stress Relaxation of Sugi (Cryptomeria japonica D.Don) Wood in Radial Compression under High Temperature Steam
- Structural Performance of Fire-Retardant Treated Plywood: Effect of Elevated Temperature
- Sorption Behaviour and Dimensional Changes of Wood-Coating Composites
- Literature Reports
