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The development of a simple surface barrier discharge plasma device is presented to enable more widespread access to and utilization of plasma technology. The application of the plasma device was demonstrated for pretreatment of wood prior to application of protective coatings for outdoor usage. The coatings' overall performance was increased, showing a reduction or absence of cracking due to weathering on plasma-pretreated specimens. Moreover, after ten months of outdoor weathering, the plasma-pretreated specimens showed fewer infections with biotic factors and improved adhesion performance in cross-cut tests, while the surface gloss performed independently from plasma pretreatment. In contrast to that, plasma-pretreated specimens were slightly more prone to discoloration due to outdoor weathering, whereas the plasma pretreatment did not impact the initial color after coating application. [ABSTRACT FROM AUTHOR]

Color changes of thermally modified timber due to different formulations of polyacrylate coating were studied before and after the application of the coatings. Olive leaf extract as a natural antioxidant-bearing additive was added to polyacrylate to examine any changes in color parameters in comparison with other additives. Water contact angle, surface roughness, and the color parameters in L*a*b* coordinates were measured, and any differences (ΔE*, ΔC*, ΔH*, ΔL*, Δa*, Δb*) were also calculated after applying the formulated coats on the thermally modified wood. The results indicated that lightness decreased after coating. The Δa* value was also increased after application of the olive leaf extract to the thermally treated wood. In general, total color change (ΔE*) was increased after coating. Reduction of ΔC* was found in the coating containing TiO2 with 10% antioxidant. Also, ΔH* was increased by the use of the polyacrylate coating containing TiO2, compared with other coatings. Application of all of the formulated coatings on the wood surface led to improvement in the water contact angle over the evolution time. On the other hand, coating of the treated wood was responsible for the formation of a smooth surface in comparison with the uncoated thermally modified timber. [ABSTRACT FROM AUTHOR]

Poly(vinyl) alcohol (PVA)/nanosilica (SiO2) based electrospun nanofibers has been deposited on wood substrate by means of the roll electrospinning process. The nanofibrous coating was hydrophobized by self-assembled monolayers of octadecyltrichlorosilane (OTS) via a solgel dipping process. The PVA/SiO2 nanofiber coating and OTS hydrophobized coating were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDXA). All methods confirmed the formation of OTS monolayers on hybrid coatings. The adhesive strength and resistance to scratch of nanofibers coating was also evaluated. [ABSTRACT FROM AUTHOR]

ABSTRACT Preparation of polyurethane wood coatings based on copper-, chromium-, and boron (CCB) containing liquefied wood was performed, as an alternative way to manage postconsumed preservative-contaminated wood. Additionally, we examined the possibility of improvement of selected properties of the liquefied wood-based coatings by an addition of silica nanoparticles. The constituents of the CCB wood preservative do not exhibit an influence on a liquefaction process and on composition of the liquefied mixture. CCB also does not affect curing of the formulations containing liquefied wood and an isocyanate-type hardener. Furthermore, influence of CCB on adhesion strength of liquefied wood-based coatings on a wooden substrate, their hardness, and resistance to scratching and to water, acetone, and alcohol, is not exhibited. However, apart from these, from the applicative point of view, positive results, any improvement of the coating properties by the addition of silica nanoparticles is not shown. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40865. [ABSTRACT FROM AUTHOR]

Modification of wood can change its hydrophilic character. Consequently, modified wettability of wood can change its behavior with coating or gluing processes. The authors investigated the wettability of oil-heat-treated and DMDHEU-modified Scots pine wood with some commercial waterborne coatings. The increased hydrophobic character of modified wood was revealed from high advancing contact angles of water. In contrast, exterior waterborne coatings exhibited much better wetting on modified substrates than on unmodified substrates. Good wetting of modified wood by waterborne coatings is an interesting result, opening up possibilities for application of environmentally friendly waterborne surface systems on modified wood. [ABSTRACT FROM AUTHOR]

The purpose of this study was to comparatively investigate the behavior of silicate and sol-silicate coatings non-modified or modified with an organosilane on wood and on wood pre-coated with silica-mineralized primers. Adhesion strength, morphology, and water permeability and related damages were studied to evaluate the possibility of utilizing such inorganic-based coating systems for durable protection of wood without or with relatively cheap and water-borne primers. Potassium silicate and potassium methylsiliconate aqueous solutions and a colloidal silica were used for the preparation of the coatings. The white coating paints were brushed on beech wood substrates at a rate of 220 g·m−2. The coatings exhibited good coverage ability. The pull-off adhesion strength values appeared to be related to pH following a polynomial law. The adhesion strength for the silicate coatings were adequate (above 3 MPa and up to 5 MPa) for wood, whereas the values for the sol-silicates were too low for practical applications. The adhesion values were in general higher for the samples cured in a climate room (23 ± 3 °C and 75 ± 2% relative humidity) than the samples cured in the ambient atmosphere of the laboratory (23 ± 3 °C and 25 ± 5% relative humidity). The presence of microdefects (cracks, holes) was revealed in the coating layers by optical and scanning electron microscopy. The surface roughness parameters assessed by confocal scanning laser microscopy were dependent on the magnification applied for their measurement. The arithmetic average roughness Sa was between 5 µm and 10 µm at magnification 5× and between 2.5 μm and 10 µm at magnification 20×. The maximum peak-to-valley height Sz confirmed the presence of open pores emerging through the coatings. The open pores constitute free pathways for water ingress through the coatings, and could explain the high water absorption of the coatings including the methysiliconate-containing silicate coating and despite the relatively high water contact angle and low wettability exhibited by this sample. The post-application of a hydrophobizing solution containing hexadecyltrimethoxysilane and dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride considerably reduced the water permeability, while application of nanosilica-containing organic primers increased the adhesion for the coatings. Silicate coatings with adhesion great enough and resistance against water damages can be generated on wood even without a primer using low silica-to-alkali ratio binders and an organosilane additive. The sol-silicate coatings appear to be applicable only with a primer. The improvement of the paint formulations to control the formation of microcracks and open pores could be useful to reduce the liquid water permeability and increase durability. Otherwise, the application of a hydrophobizing treatment can be used for this purpose. [ABSTRACT FROM AUTHOR]

Parquet flooring is one of the most common types of flooring, the surface of which can be covered with various coatings. To avoid possible damage to the parquet during use, it is necessary to test the surfaces before installation according to various non-standard and standard protocols. The present study provides an overview of the interactions between the properties of selected waterborne coatings (solids content, hardness, resistance to cracking, tensile strength) and the properties of oak wood flooring surfaces (dry film thickness, coating adhesion, resistance to scratching, impact, abrasion and cold liquids). The tests conducted showed that the performance of the surface systems was highly dependent on the coating formulations, as they were either one- or two-component systems. Although no major differences in surface resistance to cold liquids were found, there was a correlation between coating thickness, hardness and tensile strength. The harder coatings had higher tensile strengths and lower elongations. The coatings with higher tensile strength and better hardness achieved better adhesion properties. The coatings that exhibited ductile behavior showed the worst scratch resistance. A statistically significant relationship was found between the higher resistance of the flooring systems to impact stress and the improved abrasion resistance. The obtained results provide potential end users of surface coatings with valuable information on the quality that can be expected in wood flooring. [ABSTRACT FROM AUTHOR]

Silicate coatings are environmentally friendly inorganic-based products that have long been used for mineral substrates and protection of steel against corrosion. The development and acceptance of these coatings in the wood sector require some adjustments in formulations or special preparation of the surface to be coated to obtain durable finishes. In this work, the adhesion of various silicate-based formulations to a beech wood substrate (Fagus sylvatica L.), was assessed with the main objective to study relevant parameters and potential improvements. Adhesion strength was determined by pull-off and cross-cut tests. Other coating properties such as scratch, impact, and water resistance were also determined. Surface roughness and interface were analyzed using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), and coating curing was studied by attenuated total reflection-infrared spectroscopy (ATR FTIR). The results showed that adhesion was highly dependent on formulation, penetration of the coatings into wood, and mechanical anchoring. Increasing the content of solid particles in the coating formulations or adding a polyol (glycerol, xylose), which probably acted as a coalescent, considerably decreased the adhesion strength, probably by blocking penetration into the wood by forming aggregates. Adhesion was improved by pre-mineralization of the surface, and substitution of a part of the potassium silicate binder with potassium methyl siliconate reduced the formation of cracks caused by dimensional instability of the wood. [ABSTRACT FROM AUTHOR]

The selection of the wood surface pre-treatment process prior to finishing for an optimal wood-coating relationship can be challenging, but has a great significance for the properties of the coated products. The present study compares the surface properties of beech (Fagus sylvatica L.) wood after mechanical (MT), physical (PT) and chemical (CT) treatment and shows the relationships of the pre-treated wood with original (O) and diluted (D, 10% water addition) waterborne opaque coatings. Wood was found to have the most oxidized surfaces (O/C ratio of 0.7) and a pronounced polar character (water contact angle 24°) after PT with atmospheric plasma discharge, followed by surfaces exposed to MT (O/C ratio 0.6, 52°) and surfaces exposed to CT (O/C ratio 0.4, 94°), representing surface treatment with an organic solvent. Changes in the cell structure of the wood and reduced surface roughness (S a decreased by −2.0%) were observed only after CT. The best wettability with coatings was observed on wood exposed to PT and CT, reaching the values of advancing contact angles of 94° and 89° for O coating and 71° and 75° with D coating, respectively. This shows that it is not the surface condition of the wood that has the greatest influence on the wettability with the coatings used, but the properties of the coatings play a major role. After applying the coatings to the pre-treated wood surfaces, the thicker (between 60 μm and 41 μm) coating films were found on the wood coated with O coating than on the wood coated with D coating (between 47 μm and 37 μm). Despite some differences in the determined coating penetration depths, no general statement could be made about the influence of the type of surface pre-treatment. The highest adhesion strengths of the O coating and the D coating were found on the wood surfaces after CT (6.4 MPa and 5.4 MPa), MT (4.6 MPa and 4.5 MPa) and the smallest on the surfaces after PT (2.2 MPa and 2.5 MPa). The reasons for the contradictions between the wettability with coatings and the adhesion strength could be due to the formulation of the coatings studied, which seems to adhere better to wood substrates pre-treated with an organic solvent. [Display omitted] • The most hydrophilic wood surfaces achieved after mechanical and physical treatment. • Coatings comparatively good wet wood surfaces treated with plasma and organic solvent. • Properties of coatings play a major role in the wetting of wood surfaces. • Highest adhesion strengths of coatings on wood surfaces treated with organic solvent. [ABSTRACT FROM AUTHOR]