Plasma Pre-treatments to Improve the Weather Resistance of Polyurethane Coatings on Black Spruce Wood
We hypothesize that plasma treatments that increase the adhesion and penetration of transparent water, and solvent-borne polyurethane coatings into black spruce wood will improve the performance of coated wood exposed to accelerated weathering. We tested this hypothesis by modifying wood samples wit...
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doaj-2c9701c4786d4a81a64066e35ce0543f2020-11-25T00:13:44ZengMDPI AGCoatings2079-64122018-12-0191810.3390/coatings9010008coatings9010008Plasma Pre-treatments to Improve the Weather Resistance of Polyurethane Coatings on Black Spruce WoodJonathan G. Haase0Lukie H. Leung1Philip D. Evans2Faculty of Forestry, University of British Columbia, Vancouver, BC V6T 1Z4, CanadaFaculty of Forestry, University of British Columbia, Vancouver, BC V6T 1Z4, CanadaFaculty of Forestry, University of British Columbia, Vancouver, BC V6T 1Z4, CanadaWe hypothesize that plasma treatments that increase the adhesion and penetration of transparent water, and solvent-borne polyurethane coatings into black spruce wood will improve the performance of coated wood exposed to accelerated weathering. We tested this hypothesis by modifying wood samples with plasma for 30, 180, 600, and 1200 s, and measuring coating penetration and adhesion using light microscopy and a mechanical pull-off test, respectively. Plasma treatment did not improve coating adhesion, but the solvent-borne coating showed deeper penetration into plasma-modified wood, and its resistance to accelerated weathering was better on plasma-modified wood than on untreated controls. Plasma treatments enhanced the penetration of water-borne polyurethane into wood, but the treatments did not improve weather-resistance of the coating. Plasma treatment increased the wettability of wood surfaces, and prolonged plasma treatment etched cell walls, increasing their porosity. These effects may explain the positive effect of plasma treatment on coating penetration, and the increased weather-resistance of the solvent-borne polyurethane on plasma-modified wood. In conclusion, our results indicate that the ability of plasma treatment to improve coating performance on black spruce depends on the coating type, and the effects of the treatment on the surface microstructure of wood.http://www.mdpi.com/2079-6412/9/1/8woodclear polyurethane coatingsplasmapenetrationadhesionaccelerated weatheringdefectsblack spruce |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Jonathan G. Haase Lukie H. Leung Philip D. Evans |
spellingShingle |
Jonathan G. Haase Lukie H. Leung Philip D. Evans Plasma Pre-treatments to Improve the Weather Resistance of Polyurethane Coatings on Black Spruce Wood Coatings wood clear polyurethane coatings plasma penetration adhesion accelerated weathering defects black spruce |
author_facet |
Jonathan G. Haase Lukie H. Leung Philip D. Evans |
author_sort |
Jonathan G. Haase |
title |
Plasma Pre-treatments to Improve the Weather Resistance of Polyurethane Coatings on Black Spruce Wood |
title_short |
Plasma Pre-treatments to Improve the Weather Resistance of Polyurethane Coatings on Black Spruce Wood |
title_full |
Plasma Pre-treatments to Improve the Weather Resistance of Polyurethane Coatings on Black Spruce Wood |
title_fullStr |
Plasma Pre-treatments to Improve the Weather Resistance of Polyurethane Coatings on Black Spruce Wood |
title_full_unstemmed |
Plasma Pre-treatments to Improve the Weather Resistance of Polyurethane Coatings on Black Spruce Wood |
title_sort |
plasma pre-treatments to improve the weather resistance of polyurethane coatings on black spruce wood |
publisher |
MDPI AG |
series |
Coatings |
issn |
2079-6412 |
publishDate |
2018-12-01 |
description |
We hypothesize that plasma treatments that increase the adhesion and penetration of transparent water, and solvent-borne polyurethane coatings into black spruce wood will improve the performance of coated wood exposed to accelerated weathering. We tested this hypothesis by modifying wood samples with plasma for 30, 180, 600, and 1200 s, and measuring coating penetration and adhesion using light microscopy and a mechanical pull-off test, respectively. Plasma treatment did not improve coating adhesion, but the solvent-borne coating showed deeper penetration into plasma-modified wood, and its resistance to accelerated weathering was better on plasma-modified wood than on untreated controls. Plasma treatments enhanced the penetration of water-borne polyurethane into wood, but the treatments did not improve weather-resistance of the coating. Plasma treatment increased the wettability of wood surfaces, and prolonged plasma treatment etched cell walls, increasing their porosity. These effects may explain the positive effect of plasma treatment on coating penetration, and the increased weather-resistance of the solvent-borne polyurethane on plasma-modified wood. In conclusion, our results indicate that the ability of plasma treatment to improve coating performance on black spruce depends on the coating type, and the effects of the treatment on the surface microstructure of wood. |
topic |
wood clear polyurethane coatings plasma penetration adhesion accelerated weathering defects black spruce |
url |
http://www.mdpi.com/2079-6412/9/1/8 |
work_keys_str_mv |
AT jonathanghaase plasmapretreatmentstoimprovetheweatherresistanceofpolyurethanecoatingsonblacksprucewood AT lukiehleung plasmapretreatmentstoimprovetheweatherresistanceofpolyurethanecoatingsonblacksprucewood AT philipdevans plasmapretreatmentstoimprovetheweatherresistanceofpolyurethanecoatingsonblacksprucewood |
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