Print Email Facebook Twitter Understanding the influence of wood as a substrate on the permeability of coatings by NMR imaging and wet-cup Title Understanding the influence of wood as a substrate on the permeability of coatings by NMR imaging and wet-cup Author Gezici-Koç, Ö. Erich, S.J.F. Huinink, H.P. van der Ven, L.G.J. Adan, O.C.G. Publication year 2018 Abstract An important reason to apply coatings on wood is to protect wood against moisture. As a result of regulations and ecological concerns, there has been a shift towards waterborne coatings, which make coatings intrinsically more sensitive to water. As a consequence of the higher sensitivity to water, the durability of both wood and coatings can be negatively affected. In order to use waterborne coatings for woodcare, the main factors influencing transport through these coatings have to be understood. The aim of this study is to elucidate the influence of the wooden substrate on the water permeability of the coating applied to it. Pine sapwood, oak and teak were selected as the wood types, covering a whole range of low to high density wood. Three types of coatings were formulated: a solventborne alkyd, a waterborne alkyd and a waterborne acrylic. NMR imaging was used to measure the moisture distribution and quantify the changes in bound and free water in coated wood during drying. For all wood-coating combinations that were investigated, water transport appeared to be externally (i.e. coating) limited. The loss of bound water started only after evacuation of free water, which showed a local thermodynamic equilibrium associated with bound and free water. We furthermore compared water permeability of free films and wood supported films to understand the influence of the wood-coating interactions. The permeability of free coating films has been determined by the wet-cup method, followed by investigating the solubility and diffusion of water in order to understand the differences in the permeability. We found that the interaction of the coating with the wood has no influence on the water permeability for the considered combinations. Furthermore, the permeability is largely determined by the water solubility. © 2017 Elsevier B.V. Subject Nano TechnologyMAS - Materials SolutionsTS - Technical SciencesMaterialsIndustrial InnovationCoatingsPermeabilityCoatingsDiffusion coatingsMagnetic resonance imagingMoistureSolubilityWaterWoodBound and free waterDiffusion of waterLocal thermodynamic equilibriumMoisture distributionNMR-imagingWater solubilitiesWaterborne acrylicsWet-cupMechanical permeability To reference this document use: http://resolver.tudelft.nl/uuid:a7b43271-2056-4fcc-9dd4-69132a0d391f DOI https://doi.org/10.1016/j.porgcoat.2017.10.013 TNO identifier 782484 ISSN 0300-9440 Source Progress in Organic Coatings, 114, 135-144 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.