Polyurethane Varnish Research Articles

Surface Characteristics and Acoustical Properties of Bamboo Particle Board Coated with Polyurethane Varnish

Using bamboo particle board as a wall divider, a furniture component, or an automotive component with a sound absorber function may be a viable option for architects and engineers seeking to achieve desired acoustical qualities, including noise reduction. However, there is still a dearth of research on the effect of particle board finishing and coatings on acoustical sound absorption and noise reduction qualities. This study, therefore, aims to determine the surface characteristics and acoustical properties of bamboo particle board, coated with polyurethane (PU). The single-layer homogeneous particle boards were constructed using particles classified as fine and coarse with two different board densities, and coated with a high-quality PU lacquer. This study found that the coating treatment of 0.3 mm 0.6 mm succeeded to significantly decrease surface roughness, as well as thickness, swelling, and water absorption, with the thickness coating as a dominant factor compared with board density and board particle size. Adding a PU coating increases sound absorption performance at low frequencies, but significantly reduces acoustical properties at high frequencies. The increase of particle board density leads to the decrease in noise reduction coefficient capability. Results obtained from this study are useful to determine the optimal coating thickness in terms of evaluating acoustical panel products.

Thermal Stability of Polyurethane Coating Prepared by Using Diphenylolpropane

Thermal stability on air of polyurethane varnish coating prepared from diphenylolpropane, polyetherpolyol and polyisocyanate was assessed. The presence of urethane groups, formed by phenolic hydroxyl of diphenylolpropane, in the polymer structure was shown to decrease its thermooxidative degradation onset temperature. At the same time, deceleration of thermooxidative processes due to stabilizing effect of diphenylolpropane released at the beginning of thermal decay of polyurethane is observed in the higher temperature region.

(Invited) Progress in Using Carbon Nanotube Spectra for Mechanical Strain Sensing

A characteristic property of semiconducting single-wall carbon nanotubes (SWCNTs) is distinct near-infrared photoluminescence following excitation by visible light. Theory and experiment show that these optical emission peaks shift predictably in wavelength as nanotubes are compressed or stretched along their axis. We are exploiting this effect in a powerful new method intended for measuring mechanical strain in critical infrastructure components such as airframes, pressurized vessels, pipelines, support beams, etc. The method involves applying a dilute dispersion of nanotubes in a polymeric host onto the surface of the specimen to form a sub-micron thick film in which SWCNTs act as strain sensors. This layer is overcoated with a transparent protective top coat such as a polyurethane varnish. Subsequent strains in the substrate are transmitted to the nanotubes by load transfer. The substrate strain magnitude and direction are then measured by illuminating the surface at any point of interest with a small visible laser beam and spectrally analyzing the resulting near-IR nanotube emission. Single-point measurements currently provide strain magnitude resolution of ca. 50 microstrain, strain angle resolution of ca. 5 degrees, and spatial resolution of ca. 50 mm. Each reading takes less than one second, allowing compilation of strain maps from scanned data. Unlike digital image correlation, which is currently the only commercial non-contact strain technology, the new method can measure strains accumulated when the specimen is not under observation. It thus has the potential for routine use in industrial structural health monitoring as well as in testing and development laboratories. Results will be presented showing strain measurements in metallic, plastic, and concrete specimens. We will also describe recent progress in adapting the technology to camera-based measurements using spectrally resolved fluorescence imaging.

Weathering characteristics of impregnated and coated Calabrian pine wood

This study was designed to investigate the weathering characteristics of Calabrian pine (Pinus brutia) wood. The wood specimens were impregnated with some copper-based chemicals and then varnish coated. As copper-based chemicals, Celcure C4, Korasit KS, and Tanalith E 8000 were used for impregnation. Polyurethane varnish (PV) and water-based varnish (WBV) were used as coating materials. Firstly, Calabrian pine wood was impregnated with 2,5 % and 5 % aqueous solutions of chemicals then coated with polyurethane varnish and WBV. Impregnated and coated Calabrian pine wood specimens were subjected to 6 months of natural weathering in Mugla, Turkey. After weathering; surface hardness, surface roughness, and adhesion strength changes of Calabrian pine wood specimens were determined. Impregnation caused to increase in surface hardness values of Calabrian pine. Surface hardness increases of water-based varnish coated Calabrian pine specimens were higher than polyurethane varnish coated Calabrian pine specimens. Impregnation resulted in higher surface roughness values of Calabrian pine specimens. Polyurethane varnish coated Calabrian pine specimens gave higher surface roughness than water-based varnish coated Calabrian pine specimens. The adhesion strength values of all treatment groups were decreased after weathering. In general, adhesion strength decreases of water-based varnish coated Calabrian pine specimens were higher than that of polyurethane varnish coated Calabrian pine specimens. The concentration levels of chemicals did not have a significant effect on surface roughness and adhesion strength of Calabrian pine wood after weathering

Heat-Resistant Polyurethane Coatings

Polyurethane varnishes synthesized using complex aromatic oligoester diols. The coatings obtained from the varnishes are temperature resistant. The influence of the molecular mass and the structure of aromatic oligoester diol, as well as the origin of isocyanate, are studied from the standpoint of influencing coating properties. A composition of polyurethane varnish is found that makes heat-resistant coatings featuring a wide range of physical, mechanical, and protective properties.

Light-Activated Antimicrobial Surfaces Using Industrial Varnish Formulations to Mitigate the Incidence of Nosocomial Infections.

Evidence has shown that hospital surfaces are one of the major vehicles of nosocomial infections caused by drug-resistant pathogens. Smart surface coatings presenting multiple antimicrobial activity mechanisms have emerged as an advanced approach to safely prevent this type of infection. In this work, industrial waterborne polyurethane varnish formulations containing for the first time cationic polymeric biocides (SPBs) combined with photosensitizer curcumin were developed to afford contact-active and light-responsive antimicrobial surfaces. SPBs were prepared by atom transfer radical polymerization, which allows control over the polymer features that influence antimicrobial efficiency (e.g., molecular weight), while natural curcumin was employed to impart photodynamic activity to the surface. Antibacterial testing against Gram-negative Escherichia coli revealed that glass surfaces coated with the new formulations displayed photokilling effect under white-light (42 mW/cm2) irradiation within only 15 min of exposure. In addition, it was observed a combined antimicrobial effect between the two biocides (cationic SPB and curcumin), with a higher reduction in the number of viable bacteria observed for the surfaces containing cationic SPB/curcumin mixtures in comparison with the one obtained for surfaces only with polymer or without biocides. The waterborne industrial varnish formulations allowed the formation of homogeneous films without the need for addition of a coalescing agent, which can be potentially applied in diverse surface substrates to reduce bacterial transmission infections in healthcare environments.

Research of the influence of quantitative content and type of hardener on the properties of water-emulsion varnishes of domestic production

In recent years, water-soluble, water-emulsion and other relatively environmentally friendly materials have become widespread. In the manufacture of products in enterprises, the consumer is less interested in the type of finishing material, but there is a direction associated with the finishing processes that directly affect the final consumer. This direction is the equipment of wooden floor coverings. Since most of these floor coverings are installed without finishing, they need further finishing directly on the installation site. Therefore, in order to reduce the negative impact on the health of the consumer, finishing works are carried out with acrylic, acrylic-polyurethane or polyurethane water-emulsion materials. Since the coatings formed by acrylic emulsions have low resistance to abrasion and water, they are mostly used for the manufacture of primers. Polyurethane or polyurethane-acrylic emulsions are used to make high-quality varnishes. It should be noted that in order to ensure high performance indicators, preference is given to two-component compositions which include a varnish-base and an isocyanate hardener. Most of the raw materials for manufacturing of two-component water-emulsion polyurethane varnishes are imported and quite expensive. Therefore, the urgent task is to establish the optimal ratio between its components. This is necessary to obtain cost-effective materials that will form h
 In recent years, water-soluble, water-emulsion and other relatively environmentally friendly materials have become widespread. In the manufacture of products in enterprises, the consumer is less interested in the type of finishing material, but there is a direction associated with the finishing processes that directly affect the final consumer. This direction is the equipment of wooden floor coverings. Since most of these floor coverings are installed without finishing, they need further finishing directly on the installation site. Therefore, in order to reduce the negative impact on the health of the consumer, finishing works are carried out with acrylic, acrylic-polyurethane or polyurethane water-emulsion materials. Since the coatings formed by acrylic emulsions have low resistance to abrasion and water, they are mostly used for the manufacture of primers. Polyurethane or polyurethane-acrylic emulsions are used to make high-quality varnishes. It should be noted that in order to ensure high performance indicators, preference is given to two-component compositions which include a varnish-base and an isocyanate hardener. Most of the raw materials for manufacturing of two-component water-emulsion polyurethane varnishes are imported and quite expensive. Therefore, the urgent task is to establish the optimal ratio between its components. This is necessary to obtain cost-effective materials that will form high-quality coatings. So, this paper presents the results of the first stage of research on the properties of two-component water-emulsion polyurethane varnishes, which are being developed by one of the Ukrainian enterprise. The results of research of hardness of the protective and decorative coverings formed by varnishes on the basis of polyurethane emulsions with addition of isocyanate hardeners are resulted. The dependence of technological parameters of varnish application on the type and quantitative content of isocyanate hardener is described.
 igh-quality coatings. So, this paper presents the results of the first stage of research on the properties of two-component water-emulsion polyurethane varnishes, which are being developed by one of the Ukrainian enterprise. The results of research of hardness of the protective and decorative coverings formed by varnishes on the basis of polyurethane emulsions with addition of isocyanate hardeners are resulted. The dependence of technological parameters of varnish application on the type and quantitative content of isocyanate hardener is described.

Effect of Surface Modification and Fibre Content on the Mechanical Properties of Coconut Fibre Reinforced Concrete

In the past few decades, concrete has been the most widely used material for structural applications in the world and uses steel reinforcement as aide to meet the flexural, tensile and ductility demands required of concrete structures. Manufacturing of concrete and steel reinforced concrete structures is associated with millions of tons of carbon dioxide emissions and mineral waste. This activity is also responsible for the depletion of a large number of non-renewable resources. Reinforcing steel is also a high cost material, consumes a lot of energy in its production. Consequently, the use of natural fibres as an alternative for steel reinforcement is widely investigated, to promote the use of sustainable concrete structures. This study aims to investigate the effect on durability, flexural, compressive, tensile properties and workability of concrete by incorporating coir fibre at varying fibre content to find the fibre content which gives optimum results. The fibre contents used were 0%, 0.5%, 1.0%, 1.5% and 2.0% by weight of cement. Furthermore, the effect of modifying the surface of the coir fibres by alkali treatment (i.e. 5 wt.% NaOH solution) and coating the fibres with epoxy paint and polyurethane varnish on coir fibre reinforced concrete (CFRC) were also investigated. Tests conducted on the CFRC specimens included slump test and flexural, compressive and tensile strength tests. Water absorption and sorptivity tests were also conducted to investigate the durability. Slump (workability) and unit weight reduced with an increase in fibre content. The surface modification methods used, had resulted in an increased workability and a reduced unit-weight. A coconut fibre content of 1% produced the best combination of flexural, tensile and compressive properties. Water absorption and sorption rate per unit time, increased with an increase of coir fibre content. It is also found that epoxy paint and alkali treatment of the fibres has a positive effect on the mechanical strength properties and also the durability and workability of the CFRC specimens. However, polyurethane varnish coating had a detrimental effect on the mechanical strength properties of the CFRC specimens.

(Invited) Progress in Using Carbon Nanotube Spectra for Mechanical Strain Sensing

A characteristic property of semiconducting single-wall carbon nanotubes (SWCNTs) is distinct near-infrared photoluminescence following excitation by visible light. Theory and experiment show that these optical emission peaks shift predictably in wavelength as nanotubes are compressed or stretched along their axis. We are exploiting this effect in a powerful new method intended for measuring mechanical strain in critical infrastructure components such as airframes, pressurized vessels, pipelines, support beams, etc. The method involves applying a dilute dispersion of nanotubes in a polymeric host onto the surface of the specimen to form a sub-micron thick film in which SWCNTs act as strain sensors. This layer is overcoated with a transparent protective top coat such as a polyurethane varnish. Subsequent strains in the substrate are transmitted to the nanotubes by load transfer. The substrate strain magnitude and direction are then measured by illuminating the surface at any point of interest with a small visible laser beam and spectrally analyzing the resulting near-IR nanotube emission. Single-point measurements currently provide strain magnitude resolution of ca. 100 microstrain, strain angle resolution of ca. 5 degrees, and spatial resolution of ca. 50 mm. Each reading takes less than one second, allowing compilation of strain maps from scanned data. In contrast to digital image correlation, which is currently the only commercial non-contact strain technology, the new method can measure strains induced when the specimen is not under observation. It thus has the potential for routine use in industrial structural health monitoring as well as in testing and development laboratories. We will also describe recent progress in adapting the technology to camera-based measurements using spectrally resolved fluorescence imaging.

Термическая стабильность полиуретанового покрытия, полученного с использованием дифенилолпропана

Thermal stability of polyurethane varnish coating prepared by using diphenylolpropane, polyetherpolyol and polyisocyanate with an equimolar ratio of isocyanate and hydroxyl groups was assessed in the air. The polyurethane weight loss thermogram shows three temperature regions: I – (217-275)°С, II – (275-380)°С, and III – above 380°С. For interpreting thermogram of the polyurethane under study the model substances simulating the urethane groups of a polymer were synthesized. The substance containing the urethane group formed by phenolic hydroxyl of diphenylolpropane was shown to demonstrate relatively low thermal stability and gets broken down into isocyanate and bisphenol. Decomposition of the substance containing the urethane group formed by alcoholic hydroxyl occurs at the higher temperature. The data obtained allow interpreting the occurrence of thermal decomposition step I in TGA curve by structural changes in the blocks formed by diphenylolpropane and polyisocyanate being the least stable when exposed to elevated temperatures. The next step can be attributed to decomposition of more thermostable urethane groups formed by functional groups of oligooxypropylenetriol and polyisocyanate. Transition to the step III accompanied by severe sample weight loss due to decomposition of urethane groups is explained by thermal oxidation of oligoether units of polymer. Based on the data obtained the conclusion was made that the presence of urethane groups formed by phenolic hydroxyl of diphenylolpropane in polymer structure results in the decreased thermooxidative decomposition onset temperature of polymer. At the same time, a deceleration of thermooxidative processes due to the stabilizing effect of diphenylolpropane released at the beginning of thermal decomposition of polyurethane is observed in a high-temperature region. The proposed polyurethane coating is inferior to commercial counterparts in thermal decomposition onset temperature but superior to them in the temperature corresponding to a 50% polymer weight loss.

Synthesis and characterisation of sulphonamide (Schiff base) ligand and its copper metal complex and their efficiency in polyurethane varnish as flame retardant and antimicrobial surface coating additives

Sulphonamide compounds are present in many bioactive compounds owing to their multiple biological applications, even their metal complexes. The study reported in this paper focused on the synthesis of a sulphonamide ligand (Schiff base) and its Cu metal complex and their possible applications as antimicrobial and flame retardant additives in polyurethane formulations for surface coating application. Thus, selected divalent (Cu II) metal complex of 4-((E)-(4-hydroxy-3-((E)-(p-tolylimino)methyl) phenyl) diazenyl)-N-(5-methylisoxazol-3-yl) benzenesulphonamide was prepared and characterised using a combination of elemental analysis, Fourier Transform Infrared, Proton Nuclear Magnetic Resonance and mass spectroscopy. The prepared Schiff base ligand and its Cu metal complex were physically added to polyurethane varnish to give varnish coating formulations at a laboratory scale and then applied onto pretreated wood and steel panels using a brush. The oxygen index, Gram negative bacteria; Gram positive bacteria and fungi values obtained indicated that the polyurethane varnish that contained the prepared ligand and its Cu metal complex as additives exhibited very good flame retardant and antimicrobial properties, respectively. It was also found that the metal complex had outperformed the ligand. The physical and mechanical resistance of the coatings was also studied, in order to assess any disadvantages owing to the incorporation of the additives. It was found that the additives did not influence the flexibility, hardness and adhesion of coating films prepared using the polyurethane varnish. The gloss of the polyurethane varnish film was improved due to the incorporation of the aromatic ring into the formulation.

Self-healing coating to reduce isothiazolinone (MCI/MI) leaching from preservative-treated bamboo

A method was developed to reduce isothiazolinone (MCI/MI) leaching from treated bamboo, thereby extending the service life of bamboo. In this study, the self-healing coatings were prepared by incorporating 10 to 12 wt% microcapsules of urea-formaldehyde resin (UF)/tung oil into conventional polyurethane varnish and acrylate varnish. In the leaching test, the self-healing coatings outperformed the control coatings. Compared with the control coatings, the average leaching rates coated by the polyurethane and acrylate self-healing coatings were reduced by 6.22% and 6.29%, respectively. In impact damage and adhesion strength tests, the ability of the self-healing coatings to withstand damage was close to the control coatings. The results indicated that self-healing coating is a feasible method to reduce the leaching of MCI/MI from treated bamboo.

Investigating the surface performance of impregnated and varnished Calabrian pine wood against weathering

Abstract The study investigates the gloss and color changes values of Calabrian pine (Pinus brutia Ten.) wood impregnated with some copper content impregnation chemicals such as Celcure C4, Korasit KS, and Tanalith E 8000 and then water-based varnish (WBV) and polyurethane varnish (PV) coated after 6 months of weathering. The results of study showed that gloss values of PV coated Calabrian pine wood were higher than that of WBV coated Calabrian pine wood before weathering. The gloss values of all treatment groups decreased after weathering. Lightness values of Calabrian pine wood also decreased for all treatment groups after weathering. Pre-impregnation before PV coating resulted in lower 𝜟L* values of Calabrian pine wood. While all treatment groups tended to turn reddish by giving 𝜟a* positive values, they tended to turn bluish by giving negative 𝜟b* values. The lowest total color change was obtained with only WBV coated Calabrian pine wood.

Effect of the Layer Structure of Wooden Floorings on Dimensional Mobility under Different Relative Humidity and Water Retention Conditions

Abstract This study aimed to determine the effect of different wood flooring layer structures and surface features on water intake, shrinkage, and swelling rates under different relative humidity and water retention conditions. Nine wood flooring sample types were tested: solid wood beech (Fagus orientalis L.) flooring covered with polyurethane varnish, four engineered wood flooring types having different core-layers (solid-wood poplar (Populus nigra L.), 2× medium-density fiberboard, and plywood) covered with ultraviolet dried polyurethane varnish on beech veneer, and four laminated wood flooring types having different core layers (high-density fiberboard, medium-density fiberboard, particleboard, and plywood). The results showed the lowest water retention increase rates for 2 and 24 hours in the high-density fiberboard and medium-density fiberboard core-layered laminated wood floorings. The lowest thickness swelling rate occurred in the laminated wood flooring with a plywood core layer during exposure to high relative humidity, whereas the lowest swelling rate in the width dimension occurred for laminated wood flooring compared with other product types. The lowest thickness shrinkage rate was in the poplar core-layered engineered wood flooring, whereas the lowest shrinkage rate in the width direction was in the medium-density fiberboard core-layered engineered wood flooring and plywood core-layered laminated wood flooring at lower relative humidities. In conclusion, high-density fiberboard and medium-density fiberboard core-layered laminated wood floorings are advisable for flooring exposed to a humid environment. All laminated wood flooring types provided good resistance to swelling. The plywood core-layered laminated wood floorings, poplar, and medium-density fiberboard core-layered engineered wood flooring types performed the best for low-humidity environments.

Accelerated weathering performance of Scots pine preimpregnated with copper‐based chemicals before varnish coating Part:1 coated with cellulosic and polyurethane varnishes

AbstractThis study aimed to determine the effect of accelerated weathering on gloss, surface hardness and colour changes of Scots pine (Pinus sylvestris L.). Test samples were impregnated with Adolit KD‐5, Wolmanit CX‐8 and Celcure AC‐500 covered with cellulosic and polyurethane varnishes. The results showed that the values of surface hardness and gloss increased after accelerated weathering. While the surface hardness of Scots pine was increased for impregnated and polyurethane‐coated varnish, it decreased for impregnated and cellulosic varnish‐coated Scots pine after 1000 hours of accelerated weathering exposure. Copper‐based chemical impregnation and varnish coating developed the gloss of Scots pine specimens relative to the surface characteristics observed in single‐coated Scots pine specimens. While the most appropriate chemical was Celcure AC‐500 for surface hardness, it was Adolit KD‐5 for the gloss of Scots pine after 1000 hours of accelerated weathering exposure. Wood specimens impregnated prior to the application of varnish were more effective in stabilising the colour of Scots pine than Scots pine only coated with varnish. Polyurethane varnish‐treated Scots pine showed better colour stability for each partial and total accelerated weathering exposure period. The total colour changes were lowest for polyurethane varnish‐coated Scots pine impregnated with Celcure AC‐500 after 1000 hours of accelerated weathering exposure.

Environmental effects on Chestnut wood (Castanea sativa Mill.) treated with different surface coatings

This study investigated the influence of climatic factors on the deterioration of chestnut wood after various manipulations with surface coatings after exposure to ambient conditions for two years. The exposure of chestnut wood surfaces to atmospheric precipitation namely snow, rain and humidity, whether coated or uncoated with hydrophobic substances of low effectiveness led to discolouration due to leaching of water-soluble extracts possessed by the wood. The handling of chestnut wood with surface coatings of hydrophobic protectives (WR) such as teak oil in an organic solvent, epoxy resin based stain, transparent polyurethane varnish with UV protection factor, surface alkyd-based white varnish and exposure to ambient atmospheric conditions showed that discolouration was created due to the leaching of the water-soluble extracts, contained in the chestnut wood for surfaces coated or uncoated with hydrophobic substances of low effectiveness. It was therefore concluded that environmental factors cause discolouration of chestnut wood whether treated or untreated with hydrophobic substances of low effectiveness.

COATING PERFORMANCES OF CRIMEAN JUNIPER (Juniperus excelsa M. BIEB.) WOOD

ABSTRACT The purpose of this study is to determine the varnish layer hardness and varnish adhesion strength of the varnished Crimean juniper (Juniperus excelsa M. Bieb.) wood growing naturally in the Kastamonu region of Turkey. Test samples were varnished with UV-resistant polyurethane alkyd resin high gloss varnish (PAV) and water-based acrylic resin gloss varnish (WBAV). The varnish adhesion strength test was carried out by using universal testing machine. The varnish layer hardness was measured by using Konig pendulum hardness tester. Additionally, the colour properties were measured by spectrophotometer equipment that used the L*a*b* colour space. The adhesion strength of the polyurethane varnish and the water-based varnish were determined 2.81 MPa and 2.25 MPa respectively. Surface hardness value for water-based varnish and polyurethane varnish were determined 71 and 25 oscillation respectively. Detecting the performance of polyurethane and water-based varnish applications for the Crimean juniper wood will provide guidance in which type of varnish will be better for finishing. As a result, in varnish applications of the wood, it is recommended that water-based acrylic varnish should be applied when surface hardness is required. In addition, polyurethane alkyd varnish should be applied when better surface adhesion strength is desired.

Alicycliphilus: current knowledge and potential for bioremediation of xenobiotics.

Alicycliphilus is a promising candidate for participating in the development of novel xenobiotics bioremediation processes. Members of the Alicycliphilus genus are environmental bacteria mostly found in polluted sites such as landfills and contaminated watercourses, and in sewage sludges from wastewater treatment plants. They exhibit a versatile metabolism and the ability to use oxygen, nitrate and chlorate as terminal electron acceptors, which allow them to biodegrade xenobiotics under oxic or anoxic conditions. Pure cultures of Alicycliphilus strains are able to biodegrade some pollutants such as industrial solvents (acetone, cyclohexanol and N-methylpyrrolidone), aromatic hydrocarbons (benzene, toluene and anthracene), as well as polyurethane varnishes and foams, and they can even transform Cr(VI) to Cr(III). In addition, Alicycliphilus has also been identified in bacterial communities involved in wastewater treatment plants for denitrification, and the degradation of emerging pollutants such as triclosan, nonylphenol, N-heterocyclic aromatic compounds (indole and quinoline), and antibiotics (tetracycline and oxytetracycline). This work summarizes the current knowledge on the Alicycliphilus genus, describing its different metabolic characteristics, focusing on its xenobiotic biodegradation abilities and examining the distinct pathways and molecular bases that sustain them. We also discuss the progress made in genetic manipulation and 'omics' analyses, as well as Alicycliphilus participation in novel bioremediation strategies.

The Investigation of Aluminium Sulphate Influences in Polyurethane Varnish Applications

Bu çalışmada, ahşap malzemelerin üst yüzey işlemlerinde kullanılan poliüretan verniğe farklı miktarda alüminyum sülfat eklenmiştir. Önceden hazırlanmış poliüretan vernik, kayın (Fagus orientalis L.) ve sarıçam (Pinus sylvestris L.) odunlarının üst yüzeylerine uygulanmıştır. Vernikleme işleminden sonra, vernik tabakaları üzerinde parlaklık, sertlik ve yüzey yapışma direnci deneyleri yapılmış ve poliüretan verniğine eklenen alüminyum sülfatın etkileri belirlenmiştir. Sonuç olarak, verniğe eklenen alüminyum sülfatın, her iki ağaç türünde sertliği önemli ölçüde arttırdığı tespit edilmiştir; Bununla birlikte, verniğin parlaklığını ve yapışma direncini büyük ölçüde azaltmıştır.

The penetration and wettability of varnish in Cryptomeria japonica

Wood products require preservative and finishing treatments to raise their quality and market value, thus making their appearance more pleasing and their strength higher. The objective of this work was to analyze the wettability of the different finishes, as well as the penetration of the products by scanning electron microscopy. The present study used Scanning Electron Microscopy (SEM) with two replicates per sample and a Goniometer to observe the behaviour of the sessile gout with 5 replicates per sample and radial position. It was concluded that the water based varnish presented a diffuse layer when observed in the SEM and the polyurethane varnish formed a film on the substrate thicker than the other treatments. The copal varnish presented a higher contact angle and the nitrocellulose lacquer formed the smallest contact angle. Copal varnish and PU showed higher hydrophobicity and higher resistance to moisture.