Research

15 pages, 2676 KiB

Open AccessArticle

Fire Performance of Intumescent Waterborne Coatings with Encapsulated APP for Wood Constructions

by Atif Hussain, Véronic Landry, Pierre Blanchet, Doan-Trang Hoang and Christian Dagenais

Coatings 2021, 11(11), 1272; https://doi.org/10.3390/coatings11111272 - 20 Oct 2021

Cited by 7 | Viewed by 3181

In this work, intumescent coatings were prepared for protection of wood from fire. The fire-retardant chemical ammonium polyphosphate (APP) is known to have poor resistance to water and high humidity as it is hygroscopic in nature. To improve the water resistance, durability and [...] Read more.

In this work, intumescent coatings were prepared for protection of wood from fire. The fire-retardant chemical ammonium polyphosphate (APP) is known to have poor resistance to water and high humidity as it is hygroscopic in nature. To improve the water resistance, durability and fire resistance of the intumescent coating, APP was modified using a hybrid organic-inorganic polysiloxane encapsulation shell prepared by the sol–gel method. The physical and chemical properties of the intumescent mix containing microencapsulated ammonium polyphosphate (EAPP) particles were characterized by X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), water absorption, dynamic vapor sorption (DVS) and thermogravimetric analysis (TGA). The EAPP mix showed 50% reduction in water absorption, 75% reduction in water vapor sorption and increased thermal stability when compared to the APP mix. The intumescent coatings were applied on wood samples, and their fire performance was evaluated using a cone calorimeter test. The intumescent coatings containing EAPP mix showed better fire retarding properties with longer time to ignition, lower heat release rate and shorter heat release peak when compared to the coating without EAPP mix. The prepared intumescent coating shows higher resistance to water and moisture, and it has great potential to be used in bio-based construction industry for enhancing the fire resistance of wood. Full article

(This article belongs to the Special Issue Recent Developments and Trends in Wood Coatings)

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12 pages, 2032 KiB

Open AccessArticle

Effects of Chromic Treatment on the Surface Properties of Polypropylene (PP) Wood Composites

by Marouan Rejeb, Ahmed Koubaa, Fayez Elleuch, François Godard, Sébastien Migneault, Besma Bouslimi, Mohamed Khlif and Hatem Mrad

Coatings 2021, 11(7), 851; https://doi.org/10.3390/coatings11070851 - 15 Jul 2021

Cited by 1 | Viewed by 2620

Abstract

The moisture sensitivity of wood–polymer composites (WPCs) is mainly related to their hydrophilic wood components. Coatings are among the alternatives that improve the dimensional stability of these composites. However, the adhesion of most coatings to the WPC surface is generally poor. Thus, chemical [...] Read more.

The moisture sensitivity of wood–polymer composites (WPCs) is mainly related to their hydrophilic wood components. Coatings are among the alternatives that improve the dimensional stability of these composites. However, the adhesion of most coatings to the WPC surface is generally poor. Thus, chemical and/or mechanical treatments should be applied to the WPC surface to improve the coating adhesion. Therefore, the main objective of this study was to improve the adhesion coating of polypropylene (PP) WPCs through a chromic treatment. PP was reinforced by three different pulp fibers (kraft, thermomechanical (TMP), and chemothermomechanical (CTMP)) at three fiber contents (50, 60, and 70% w/w). A chromic treatment was applied to the PP-based WPCs to activate the surface of the composites and alter their roughness parameters, creating a higher interfacial zone that improved the bonding of the epoxy coating to the surface of the PP composites. The chromic treatment increased the roughness of the surface. An increase in profile and surface parameters was observed after treatment. This treatment modified the chemical composition of the surface by creating polar carbon–oxygen groups and increasing the carbonyl and hydroxyl indexes. Full article

(This article belongs to the Special Issue Recent Developments and Trends in Wood Coatings)

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13 pages, 1643 KiB

Open AccessFeature PaperArticle

Effects of Coating on the Dimensional Stability of Wood-Polymer Composites

by Marouan Rejeb, Ahmed Koubaa, Fayez Elleuch, François Godard, Sébastien Migneault, Mohamed Khlif and Hatem Mrad

Coatings 2021, 11(6), 711; https://doi.org/10.3390/coatings11060711 - 13 Jun 2021

Cited by 4 | Viewed by 2228

Abstract

Wood polymer composites (WPC) are sensitive to moisture because of the hydrophilic nature of the wood fibers. The main objective of this study was to improve the dimensional stability of WPCs by coating. Polypropylene and polylactic acid were reinforced by three pulp fibers [...] Read more.

Wood polymer composites (WPC) are sensitive to moisture because of the hydrophilic nature of the wood fibers. The main objective of this study was to improve the dimensional stability of WPCs by coating. Polypropylene and polylactic acid were reinforced by three pulp fibers (kraft, thermomechanical (TMP), and chemothermomechanical (CTMP)) at three fiber contents (50, 60, and 70% w/w). The resulting WPCs were coated using two commercial coatings, epoxy and acrylic. Kraft fiber WPCs were less sensitive to moisture than TMP and CTMP WPCs. These differences were explained by the crystallinity of the kraft fibers and their better interfacial adhesion to the polymers. The epoxy coating proved to be more effective than the acrylic coating and significantly reduced the water absorption and the thickness swell for all formulations. Negative relationships between the contact angle and water absorption were obtained. These relationships depend on the fiber content and type, the matrix nature, and the coating. Full article

(This article belongs to the Special Issue Recent Developments and Trends in Wood Coatings)

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15 pages, 30595 KiB

Open AccessArticle

Effect of Calcium Carbonate Particle Size on the Scratch Resistance of Rapid Alkyd-Based Wood Coatings

by Orkun Ersoy, Sinan Fidan, Harun Köse, Dilek Güler and Ömer Özdöver

Coatings 2021, 11(3), 340; https://doi.org/10.3390/coatings11030340 - 17 Mar 2021

Cited by 6 | Viewed by 2913

Abstract

Polymer-based wood coatings are used for aesthetic purposes as well as to protect wood surfaces, especially under external conditions. High-hardness mineral fillers are thought to enhance the resistance of these polymer coatings to wear and scratching. However, recent studies suggest that the relatively [...] Read more.

Polymer-based wood coatings are used for aesthetic purposes as well as to protect wood surfaces, especially under external conditions. High-hardness mineral fillers are thought to enhance the resistance of these polymer coatings to wear and scratching. However, recent studies suggest that the relatively low-hardness mineral calcite (CaCO₃, Mohs hardness of 3) performs similarly to harder minerals under external conditions. It can replace more expensive hard minerals, thus driving research interest in its use. In this study, CaCO₃ powders with different grain sizes were applied to rapid alkyd-based coating formulations, and the effect of CaCO₃ particle size on the scratch behavior of the coatings was investigated under identical test conditions. The scratch morphologies, scratch hardness, and roughness values of the scratched surfaces indicated that the surfaces of the rapid alkyd-based wood coatings including finer-grained CaCO₃ experienced plastic plowing-type deformation in the form of regular, narrow, and shallow scratches, showing high scratch resistance. Coatings using coarser-grained CaCO₃ experienced more extensive plastic deformation of the plowing–tearing type owing to the weaker filler–polymer interface and the breakage of larger coating pieces from the coating surface. Full article

(This article belongs to the Special Issue Recent Developments and Trends in Wood Coatings)

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19 pages, 7246 KiB

Open AccessArticle

Analysis of a Wide Range of Commercial Exterior Wood Coatings

by Michael J. Gibbons, Saeid Nikafshar, Tina Saravi, Katie Ohno, Sanjeev Chandra and Mojgan Nejad

Coatings 2020, 10(11), 1013; https://doi.org/10.3390/coatings10111013 - 22 Oct 2020

Cited by 10 | Viewed by 2725

Abstract

This study was focused on measuring the properties of twenty-three commercially available coatings formulated for exterior wood applications. The coatings were characterized by measuring their surface tension, solid content, viscosity, pH, and glass transition temperatures (T_g). Additionally, the wetting properties [...] Read more.

This study was focused on measuring the properties of twenty-three commercially available coatings formulated for exterior wood applications. The coatings were characterized by measuring their surface tension, solid content, viscosity, pH, and glass transition temperatures (T_g). Additionally, the wetting properties of coating droplets on wood substrates were measured. The contact angle of solvent-based and water-based coatings were characterized on untreated southern yellow pine wood samples using high-resolution image analysis and the Young–Laplace solution. An innovative image processing technique for determining the average diameter of coating droplets on wood was developed, and an iterative method to calculate the average contact angle using the Young–Laplace solution was applied. The water-resistance of the coated wood samples was evaluated during one week of water immersion tests. In general, solvent-based coatings had significantly lower contact angles and water uptake than water-based coatings. Water-based paint samples had the largest average contact angle (81°), and solvent-based transparent penetrating stains had the smallest contact angle (13.9°). A strong correlation was observed between the coating water uptake and their surface tension and solid content. Full article

(This article belongs to the Special Issue Recent Developments and Trends in Wood Coatings)

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19 pages, 9849 KiB

Open AccessArticle

Self-Healing UV Curable Acrylate Coatings for Wood Finishing System, Part 1: Impact of the Formulation on Self-Healing Efficiency

by Chloé Paquet, Thomas Schmitt, Jolanta E. Klemberg-Sapieha, Jean-François Morin and Véronic Landry

Coatings 2020, 10(8), 770; https://doi.org/10.3390/coatings10080770 - 07 Aug 2020

Cited by 14 | Viewed by 4045

Abstract

In the wood flooring sector, good surface mechanical properties, such as abrasion and scratch resistance, are prerequisite. Surface wood protection is provided by finishing systems. Despite coating improvement, scratches formation on wood flooring is unavoidable. A new approach to increase service life is [...] Read more.

In the wood flooring sector, good surface mechanical properties, such as abrasion and scratch resistance, are prerequisite. Surface wood protection is provided by finishing systems. Despite coating improvement, scratches formation on wood flooring is unavoidable. A new approach to increase service life is to confer the self-healing property to the finishing system. The most common coatings used for prefinished wood flooring are acrylate UV curable 100% solids coatings. They usually have good mechanical properties and high cross-linking density. The objective of this study was to develop and evaluate an intrinsic self-healing formulation, which is applicable to wood flooring. For this purpose, acrylate formulations were developed with monomers and oligomers carrying hydroxyl groups. To meet the requirements of wood application, hardness, and polymerization conversion of coatings were evaluated. König pendulum damping tests provide information on coating hardness and flexibility. Results around 80 oscillations is acceptable for UV curable wood sealer. The chemical composition was studied by FT-IR spectroscopy while dynamical mechanical analysis (DMA) was performed to determine glass transition temperature and cross-linking density. The self-healing behavior was evaluated by gloss and scratch depth measurements. The formulation’s composition impacted the hydrogen binding quantity, the conversion, the T_g and the cross-linking density. The (hydroxyethyl)methacrylate (HEMA) monomer provided self-healing and acrylated allophanate oligomer allowed self-healing and cross-linking. This study demonstrated that it is possible to combine high cross-linking density and self-healing property, using components with low steric hindrance. Full article

(This article belongs to the Special Issue Recent Developments and Trends in Wood Coatings)

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21 pages, 3827 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Interactions between a Buffered Amine Oxide Impregnation Carrier and an Acrylic Resin, and Their Relationship with Moisture

by Simon Pepin, Pierre Blanchet and Véronic Landry

Coatings 2020, 10(4), 366; https://doi.org/10.3390/coatings10040366 - 07 Apr 2020

Cited by 1 | Viewed by 3159

Abstract

Wood used outdoor is subjected to different sources of degradation and should be protected properly. In this study, acrylic resins were added to a wood impregnation system using amine oxides and propiconazole, an organic fungicide, to create a two-part wood protection preservation treatment. [...] Read more.

Wood used outdoor is subjected to different sources of degradation and should be protected properly. In this study, acrylic resins were added to a wood impregnation system using amine oxides and propiconazole, an organic fungicide, to create a two-part wood protection preservation treatment. Since amine oxides can diffuse readily into wood, this treatment protected both the surface and inner structure of the treated wood following a simple dipping. Many aspects of the treatment were studied: the adhesion of the acrylic coatings, their permeability to water, and the impregnation depth of the propiconazole. In each case, a particular attention was accorded to the interactions between the resins and the impregnation system. Adhesion and permeability tests were coupled with an artificial aging process simulating severely wet conditions. Amine oxides reduced the adhesion of the coatings but did not impair their aging properties. Because of their hydrophilic nature, they also increased the permeability to liquid water, although they did not affect the air moisture permeability. The penetration of the propiconazole, estimated with a dye, decreased with the resin. Overall, the two parts of the treatment lightly impaired each other, but the practical aspect of this treatment may overcome these disadvantages. Full article

(This article belongs to the Special Issue Recent Developments and Trends in Wood Coatings)

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6 pages, 1164 KiB

Open AccessFeature PaperCommunication

Application of Confocal Raman Microscopy for the Analysis of the Distribution of Wood Preservative Coatings

by Toru Kanbayashi, Atsuko Ishikawa, Masahiro Matsunaga, Masahiko Kobayashi and Yutaka Kataoka

Coatings 2019, 9(10), 621; https://doi.org/10.3390/coatings9100621 - 27 Sep 2019

Cited by 7 | Viewed by 3233

Abstract

The distribution of wood preservative coatings in wood surface layer was assessed at the cellular level using confocal Raman microscopy. Raman images were created based on the fingerprint Raman bands of the different wood polymers and coating components (resin and pigment). The wood [...] Read more.

The distribution of wood preservative coatings in wood surface layer was assessed at the cellular level using confocal Raman microscopy. Raman images were created based on the fingerprint Raman bands of the different wood polymers and coating components (resin and pigment). The wood cell walls and the distribution of the resin and pigment were clearly visualized at the same time. It was concluded that confocal Raman microscopy is suitable for the evaluation of the microdistribution of wood coatings, providing valuable information for the improvement of wood coating technology. Full article

(This article belongs to the Special Issue Recent Developments and Trends in Wood Coatings)

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10 pages, 5299 KiB

Open AccessArticle

Surface Properties of Pine Scrimber Panels with Varying Density

by Jinguang Wei, Qiuqin Lin, Yahui Zhang, Wenji Yu, Chung-Yun Hse and Todd Shupe

Coatings 2019, 9(6), 397; https://doi.org/10.3390/coatings9060397 - 20 Jun 2019

Cited by 6 | Viewed by 3047

Abstract

Coating quality for scrimber products against exterior conditions is largely dependent on the surface properties. The wettability, morphology, and chemical composition of pine scrimber surfaces were investigated to better understand the surface properties. The scrimber was found to be a hydrophilic material because [...] Read more.

Coating quality for scrimber products against exterior conditions is largely dependent on the surface properties. The wettability, morphology, and chemical composition of pine scrimber surfaces were investigated to better understand the surface properties. The scrimber was found to be a hydrophilic material because the water contact angles were less than 90°. The panels with a density of 1.20 g/cm³ had the largest angle change rate (k = 0.212). As the panel density increased, the instantaneous contact angle of each test liquid (i.e., water, formamide, and diiodomethane) on the panels decreased, and so did surface free energy. Panels with higher density showed lower surface roughness. Surface roughness across the wood grain was greater than that along the grain. SEM observations showed the high-density panels had a smoother surface with fewer irregular grooves in comparison with the low-density panels. X-ray photoelectron spectroscopy (XPS) analysis indicated that more unoxygenated groups appeared on the surface of high-density panels. Full article

(This article belongs to the Special Issue Recent Developments and Trends in Wood Coatings)

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