Plasma Treatment Reduced the Discoloration of an Acrylic Coating on Hot-Oil Modified Wood Exposed to Natural Weathering

We test the hypothesis that plasma-treatment will remove oil from the surface of hot-oil modified blue-stained pine wood, and improve the adhesion and outdoor performance of a white acrylic coating on the modified wood. Modified wood was treated with water-vapour plasma, and microstructural changes at wood surfaces were examined. Plasma treatment removed oil from the surface of modified wood and etched bordered pits. The contact angle of water droplets on modified wood was 91.8°, but plasma-treatment for only 33 s reduced contact angle to less than that of the unmodified control (48.6°). The adhesion of the acrylic paint to modified wood was unaffected by plasma-treatment, but the adhesion rating of coated samples tested wet was slightly lower (3.1) than that of the coating on samples tested dry (3.5). The lightness value (CIE-L) of the acrylic coating on hot-oil modified wood samples exposed outdoors for 18 months was significantly lower (darker, 65.5) than that of the coating on similarly modified and exposed samples pre-treated with plasma (75.8). We conclude that plasma-treatment shows promise as a way of removing oil from the surface of hot-oil modified wood and reducing the discolouration of an acrylic coating on modified wood exposed to natural weathering.

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Weath ering Performance of Beech Wood Coated with Acrylic Paint Containing UV Stabilizers of Dihydroxy Benzophenone and Nano Zinc Oxide

Drvna industrija ◽

10.5552/drvind.2020.1912 ◽

2020 ◽

Vol 71 (4) ◽

pp. 403-409

Author(s):

Mehrnaz Akbarnezhad ◽

Davood Rasouli ◽

Hossein Yousefi ◽

Mahdi Mashkour

Keyword(s):

Contact Angle ◽

Zinc Oxide ◽

Beech Wood ◽

Mold Growth ◽

Acrylic Paint ◽

Color Changes ◽

Acrylic Coating ◽

Nano Zinc Oxide ◽

Water Based ◽

Nano Zinc

In this study, the effect of UV stabilizers (dihydroxy benzophenone and nano zinc oxide) on the weathering degradation of water-based acrylic coating on beech wood was investigated. The wood specimens were coated by brush and then weathered naturally for six months. The obtained results showed that the use of nano zinc oxide reduced color changes and mold growth on the surface of weathered samples. However, the results of contact angle, pull-off adhesion, colorimeter and FTIR revealed that the dihydroxyl benzophenone was not effective in preventing weathering degradation of coated wood.

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Plasma Pre-treatments to Improve the Weather Resistance of Polyurethane Coatings on Black Spruce Wood

Coatings ◽

10.3390/coatings9010008 ◽

2018 ◽

Vol 9 (1) ◽

pp. 8 ◽

Cited By ~ 3

Author(s):

Jonathan Haase ◽

Lukie Leung ◽

Philip Evans

Keyword(s):

Plasma Treatment ◽

Black Spruce ◽

Accelerated Weathering ◽

Polyurethane Coatings ◽

Plasma Treatments ◽

Spruce Wood ◽

Coating Type ◽

Weather Resistance ◽

Wood Surfaces ◽

Modified 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 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.

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The effect of air plasma treatment at atmospheric pressure on thermally modified wood surfaces

Wood Science and Technology ◽

10.1007/s00226-016-0856-7 ◽

2016 ◽

Vol 50 (6) ◽

pp. 1227-1241 ◽

Cited By ~ 18

Author(s):

Daniela Altgen ◽

Georg Avramidis ◽

Wolfgang Viöl ◽

Carsten Mai

Keyword(s):

Plasma Treatment ◽

Atmospheric Pressure ◽

Air Plasma ◽

Thermally Modified Wood ◽

Wood Surfaces ◽

Air Plasma Treatment ◽

Modified Wood

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A Method for Accelerated Natural Weathering of Wood Subsurface and Its Multilevel Characterization

Coatings ◽

10.3390/coatings11020126 ◽

2021 ◽

Vol 11 (2) ◽

pp. 126

Author(s):

Anna Sandak ◽

Jakub Sandak ◽

Marion Noël ◽

Athanasios Dimitriou

Keyword(s):

Structural Damage ◽

Structural Integrity ◽

Degradation Process ◽

Natural Weathering ◽

Bordered Pits ◽

Ft Ir ◽

Short Time ◽

Wood Surfaces ◽

Kinetics Of

The function of altering weathering factors and degradation mechanisms are essential for understanding the weathering process of materials. The goal of this work was to develop a method for the acceleration of natural weathering and to investigate the molecular, microstructure and macrostructure degradation of wood caused by the process. Tests were performed in the whole month of July, which, according to previous research, is considered as the most severe for weathering of wood micro-sections. Sample appearance was evaluated by colour measurement. Scanning electron microscopy was used for evaluation of the structural integrity and changes in the microstructure of wood morphological components. Changes on the molecular level were assessed by means of FT-IR spectroscopy. Observation of the effects of weathering allowed a better understanding of the degradation process. Typical structural damage, such as cracks on bordered pits and cross-field pits, and, as a consequence, their erosion, revealed the sequence of the degradation process. It was confirmed that earlywood was more susceptible to damage than latewood. Even if the weathering test was conducted for a relatively short time (28 days) the ultra-thin wood samples changed noticeably. The progress of alteration was similar as usually noticed for wood surfaces, but occurred at shorter exposure times. The estimated acceleration factor was ×3, compare to the natural weathering kinetics of wood. The research methodology presented can be used for the determination of the weather dose-response models essential to estimate the future service life performance of timber elements.

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Influence of moisture content on the contact angle and surface tension measured on birch wood surfaces

European Journal of Wood and Wood Products ◽

10.1007/s00107-021-01666-6 ◽

2021 ◽

Author(s):

Rami Benkreif ◽

Fatima Zohra Brahmia ◽

Csilla Csiha

Keyword(s):

Surface Tension ◽

Contact Angle ◽

Moisture Content ◽

Solid Wood ◽

Contact Angles ◽

Surface Moisture ◽

Wood Coatings ◽

The Relationship ◽

Wood Surfaces

AbstractSurface tension of solid wood surfaces affects the wettability and thus the adhesion of various adhesives and wood coatings. By measuring the contact angle of the wood, the surface tension can be calculated based on the Young-Dupré equation. Several publications have reported on contact angle measured with different test liquids, under different conditions. Results can only be compared if the test conditions are similar. While the roles of the drop volume, image shooting time etc., are widely recognized, the role of the wood surface moisture content (MC) is not evaluated in detail. In this study, the effect of wood moisture content on contact angle values, measured with distilled water and diiodomethane, on sanded birch (Betula pendula) surfaces was investigated, in order to find the relationship between them. With increasing MC from approximately 6% to 30%, increasing contact angle (decreasing surface tension) values were measured according to a logarithmic function. The function makes possible the calculation of contact angles that correspond to different MCs.

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Comparative studies of nitrogen plasma and argon plasma treatment on the strength of PBO fibre reinforced high-temperature resistant thermoplastic composite

High Performance Polymers ◽

10.1177/0954008320987296 ◽

2021 ◽

pp. 095400832098729

Author(s):

K Sudheendra ◽

Jennifer Vinodhini ◽

M Govindaraju ◽

Shantanu Bhowmik

Keyword(s):

Contact Angle ◽

High Temperature ◽

Plasma Treatment ◽

Sessile Drop ◽

Dynamic Contact Angle ◽

Argon Plasma ◽

Film Surface ◽

Fibre Surface ◽

Nitrogen Plasma ◽

Thermoplastic Composite

The study involves the processing of a novel poly [1, 4-phenylene-cis-benzobisoxazole] (PBO) fibre reinforced high-temperature thermoplastic composite with polyaryletherketone (PAEK) as the matrix. The PBO fibre and the PAEK film surface was modified using the method of argon and nitrogen plasma treatment. The investigation primarily focuses on evaluating the tensile properties of the fabricated laminates and correlating it with the effect of plasma treatment, surface characteristics, and its fracture surface. A 5% decrease in tensile strength was observed post argon plasma treatment while a 27% increase in strength was observed post nitrogen plasma treatment. The morphology of the failure surface was investigated by scanning electron microscopy and an interfacial failure was observed. Furthermore, the effect of plasma on the wettability of PBO fibres and PAEK film surface was confirmed by the Dynamic Contact Angle analysis and sessile drop method respectively. FTIR spectral analysis was done to investigate the effect of plasma treatment on the chemical structure on the surface. The results of the wettability study showed that the argon plasma treatment of the fibre surface increased its hydrophobicity while nitrogen plasma treatment resulted in the reduction of contact angle.

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Tuning the Surface Wettability of Cyclic Olefin Copolymer by Plasma Treatment and Graphene Oxide Deposition and Reduction

Polymers ◽

10.3390/polym13142305 ◽

2021 ◽

Vol 13 (14) ◽

pp. 2305

Author(s):

Fadi Dawaymeh ◽

Yawar Abbas ◽

Maryam Khaleel ◽

Anas Alazzam ◽

Nahla Alamoodi

Keyword(s):

Contact Angle ◽

Plasma Treatment ◽

Treatment Duration ◽

Chemical Reduction ◽

Surface Wettability ◽

Oxygen Plasma Treatment ◽

Microfluidic Channels ◽

Cyclic Olefin Copolymer ◽

Cyclic Olefin ◽

Reduction Methods

Selective altering of surface wettability in microfluidic channels provides a suitable platform for a large range of processes, such as the phase separation of multiphase systems, synthesis of reaction controlled, nanoliter sized droplet reactors, and catalyst impregnation. Herein we study the feasibility to tune the wettability of a flexible cyclic olefin copolymer (COC). Two methods were considered for enhancing the surface hydrophilicity. The first is argon/oxygen plasma treatment, where the effect of treatment duration on water contact angle and COC surface morphology and chemistry were investigated, and the second is coating COC with GO dispersions of different concentrations. For enhancing the hydrophobicity of GO-coated COC surfaces, three reduction methods were considered: chemical reduction by Hydroiodic acid (HI), thermal reduction, and photo reduction by exposure of GO-coated COC to UV light. The results show that as the GO concentration and plasma treatment duration increased, a significant decrease in contact angle was observed, which confirmed the ability to enhance the wettability of the COC surface. The increase in hydrophilicity during plasma treatment was associated with the increase in surface roughness on the treated surfaces, while the increase during GO coating was associated with introducing oxygen-containing groups on the GO-coated COC surfaces. The results also show that the different reduction methods considered can increase the contact angle and improve the hydrophobicity of a GO-coated COC surface. It was found that the significant improvement in hydrophobicity was related to the reduction of oxygen-containing groups on the GO-coated COC modified surface.

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Colour stability of surface finishes on thermally modified beech wood

Annals of WULS, Forestry and Wood Technology ◽

10.5604/01.3001.0015.2391 ◽

2021 ◽

Vol 114 ◽

pp. 116-124

Author(s):

Gabriela Slabejová ◽

MÁRIA ŠMIDRIAKOVÁ

Keyword(s):

Surface Finish ◽

Beech Wood ◽

Surface Finishing ◽

Colour Stability ◽

Colour Difference ◽

Surface Finishes ◽

Before And After ◽

Thermally Modified Wood ◽

Wood Surfaces ◽

Modified Wood

Colour stability of surface finishes on thermally modified beech wood. The paper deals with the influence of the type of transparent surface finish on the change of colour of the surfaces of native beech wood and thermally modified wood. At the same time, the colour stability of three surface finishes on the surfaces of native and thermally modified beech wood was monitored. Beech wood was thermally modified at temperature of 125 °C for 6 hours. The thermal treatment was performed in a pressure autoclave APDZ 240, by the company Sundermann s.r.o in Banská Štiavnica. Three various types of surface finishes (synthetic, wax-oil, water-based) were applied onto the wood surfaces. The colour of the surfaces of native wood and thermally modified wood was measured in the system CIELab before and after surface finishing; the coordinates L*, a*, b*, C*ab and h*ab were measured. From the coordinates measured before and after surface finishing, the differences were calculated and then the colour difference ∆E* was calculated. Subsequently, the test specimens with the surface finishes were exposed to natural sunlight, behind glass in the interior for 60 days. The surface colour was measured at specified time of the exposure (10, 20, 30, 60 days). The results showed that the colour of the wood surfaces changed after application of the individual surface finishes; and the colour difference reached a change visible with a medium quality filter up to a high colour difference. The wax-oil surface finish caused a high colour difference on native wood and on thermally modified wood as well. On native beech wood, the lowest colour difference after exposure to sunlight was noticeable on the synthetic surface finish. On the surface of wood thermally modified, after exposure to sunlight, the lowest colour difference was noticeable on the surface with no surface finish.

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Influence of a Hydrophobic Emulsion on the Surface Properties of Coatings of Water-Dispersion Acrylic Paint

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1040.165 ◽

2021 ◽

Vol 1040 ◽

pp. 165-171

Author(s):

Valeria V. Strokova ◽

Maria V. Nikulina ◽

Pavel S. Baskakov ◽

Alina V. Abzalilova ◽

Anastasia Y. Esina

Keyword(s):

Contact Angle ◽

Ethylene Glycol ◽

Building Materials ◽

Properties Of Coatings ◽

Hydrophobic Properties ◽

Water Emulsion ◽

Water Dispersion ◽

Acrylic Paint ◽

Functional Additive ◽

Contact Wetting Angle

The existing methods of confering hydrophobic properties to various building materials are considered. Obtaining special, including hydrophobic, properties of water-emulsion paints is a very relevant task. Previously, a method was developed for producing an emulsion of a polysiloxane stabilized with polyvinyl alcohol. The paper describes the possibility of using a hydrophobisating emulsion of polyhydrosiloxane as a functional additive for an acrylic water-dispersion paint. This emulsion is capable of forming coatings on dense and porous surfaces with an adjustable contact angle up to 105 °. The use of this emulsion, with its sufficient coalescence for volumetric hydrophobization of coatings, makes it possible to obtain a high contact angle on the surface. In the paper, it was assumed that the partial introduction of small amounts (up to 10 %) of a hydrophobizing emulsion into water-dispersion paints would allow achieving the contact angle of wetting for similar coatings consisting exclusively of emulsion. It is shown that the introduction of small amounts of a hydrophobizing emulsion with an auxiliary coalescing action of ethylene glycol makes it possible to impart hydrophobic properties to the surface of the resulting coating. When the optimum concentration of ethylene glycol in the coating is reached, dissolution and transport (yield) of polysiloxane to the surface is ensured. The research carried out made it possible to develop a paint composition with a hydrophobizing emulsion with a contact wetting angle of about 100 °, which ensured the hydrophobicity of the previously hydrophilic coating of a water-dispersion acrylic paint.

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