In this study, the impact of incorporating cellulose nanofibrils (CNF) and carboxylated organo‐montmorillonite (OMMT), separately or in combination, into a UV‐curable wood coating was evaluated for ...performance enhancement. This study investigated the influence of nanoparticle loading percentage on the mechanical properties and thermal behavior of the coating, as well as the surface properties of digitally printed decorative wood‐based panels. The results indicated that the addition of CNF or OMMT increased the viscosity of the polymer solutions. Although CNF randomly oriented within the matrices, OMMT adhered to the surface of the polymer matrix. Chemical crosslinking was observed between CNF/OMMT and the coating. The addition of CNF and OMMT improved the thermal stability of the neat UV curing coating. The tensile strength of nanocomposite films with a 6 wt% loading of CNF increased significantly from 7.63 MPa to 12.73 MPa compared to pure films. The reinforcing effect of CNF on the tensile performance was significantly better than that of OMMT. Adding CNF to the matte coating slightly improved the clarity of the printed decorative panels. When CNF and OMMT were added together in the coating, there was a synergistic enhancement in the low gloss and high pencil hardness of the panels.
Highlights
Both CNF and OMMT were chosen to achieve performance improvements
A simple filling method was adopted for preparation of reinforced coating
The nanocomposite films exhibited fine thermal and mechanical properties
The better integrated property was obtained from the C + CNF3 + OMMT0.8 sample
The physicochemical interaction of nanofiller with polymer molecule existed
Fabrication process of digital printing decorative panel. Enhancement mechanism of UV‐curable wood coatings by cellulose nanofibrils and carboxylated organo‐montmorillonite.
The prospective applications of wood in the furniture industries and building sector are constrained owing to its inherently flammable nature. The application of coatings with flame retardants (FRs) ...onto the wood substrate is a well-recommended approach to mitigate the risk of fire. Non-halogenated FRs, on the other hand, have gained popularity over halogenated FRs, as halogenated FRs are under regulatory scrutiny due to their carcinogenicity and bio-accumulation issues despite offering excellent FR performance. Furthermore, given the green chemistry principles, it is also recommended to use solvent-free or environmentally benign solvents to make such coatings. The ultraviolet (UV)-assisted curing process is advantageous as it can in practice avoid the use of solvents. A few relevant pieces of literature were found in the bibliographic search databases from January 2015 to December 2022 on UV-curable, non-halogenated FRs for wood coating applications. The current review focuses on the design strategies of reactive and non-halogenated FRs with UV-curable functionalities adapted in recent years, and their applications in various UV-curing polymeric systems such as epoxy acrylate, polyurethane acrylate, thiol-ene systems, and oligomeric systems obtained from bio-based oils'. The significant findings of several research groups, the major insights gained and perspectives are covered.
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•Summarizes the effectiveness of UV-curing chemistry in designing FR wood coatings.•Highlights the importance of non-halogenated FRs under declared SDGs set globally.•The documented reports of various reactive FRs over the last decade are covered.•Discusses the reactive and non-halogenated FRs with UV-curable functionalities•The underlying mechanism of FR action is outlined as guide to design strategies to be adopted.
Growing concerns about indoor air pollution heighten the need to develop depolluting materials to achieve a healthy built environment. This study developed functional coatings for wooden surfaces ...using 20 wt% photocatalytic biocarbon particles doped with manganese oxide (BC–MnO2) and two different coating materials (linseed oil and waterborne acrylic). The samples' surface hydrophobicity and color properties were tested before and after accelerated aging. The depolluting potential of the samples was evaluated by formaldehyde removal efficiency test in indoor conditions. Results showed that adding BC-MnO2 particles increased the hydrophobicity regardless of the coating material's type. After accelerated aging, the hydrophobicity of all samples increased, which was attributed to the curing of the oil and acrylic polymers and the increase in surface roughness eventually caused by surface damage. The color change (ΔE) was more intense in the case of uncoated wood and samples without BC-MnO2. However, the BC-MnO2-containing coatings were effective in color preservation (ΔE < 2), which was attributed to the anti-UV property of biocarbon. The BC-MnO2-containing coatings exhibited a promising formaldehyde removal efficiency of up to 24 % and 46 % for oil and acrylic samples, respectively. The combination of BC-MnO2 and acrylic material was more favourable to attracting the formaldehyde molecules, likely due to the similar polarity. The developed functional coatings exhibited an acceptable ability for wood protection and formaldehyde remediation and can be potentially used to enhance indoor air quality.
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•Functional coatings were produced to reduce indoor formaldehyde concentrations.•Biocarbon-MnO2 particles improved acrylic and oil-based coatings' hydrophobicity.•Biocarbon-MnO2-containing coatings preserved their original color after aging.•Up to 46 % formaldehyde removal efficiency was achieved with functional coatings.•The depolluting potential of the coatings was verified in indoor conditions.
Abstract Fireproof coatings are the simplest, most efficient, and oldest method for protecting a wide range of flammable products, such as wood. Furthermore, surface ignition is the initial phase, so ...surface protection is essential to reduce fire propagation. Furthermore, delaying the spread of flames can help to save someone when a fire starts. This project synthesized flame-resistant resin starting from tetraallyloxysilane monomer as a halogen-free monomer, an intrinsic flame retardant co-curing agent. The following step synthesized polyester resin using terephthalic acid as a heat-resistant resin. Unsaturated polyester was used by bulk radical polymerization. FT-IR and 1 H-NMR analysis showed the successful synthesis of the desired monomer and polymeric compound. The thermal degradation and flame retardancy of pure unsaturated polyester resin (UPE) and allyloxysilane-unsaturated polyester (AUPE) were investigated by thermogravimetric analysis (TGA/DTG/DSC). The burning test and the thermal stability of the coating layers were evaluated using standard UL 94. Physical properties of resins were evaluated using Heat Deflection Temp tests (HDT) ISO 75-A, ASTM 648, Hardness ASTM D2583, Volumetric shrinkage ASTM 3521, and Water absorption ASTM D570. The results of the tests show the successful synthesis and their flame retardant properties.
Wood is an ever more demanded material for sustainable construction. However, to perform accordingly, most of the material has to be coated, usually with a petroleum-based polymeric lacquer. Due to ...difficult removal of the coating layers, coated wood is usually discarded at its end-of-life, resulting in lost value and environmental issues. To tackle this challenge, we aim to establish an integral recycling process, based on the principles of circular economy. As a first step, we herein introduce a novel technique for efficient and feasible separation of wooden substrate and coating at end-of-life. To this end, we developed a thermally triggerable primer based on nitrocellulose (NC) which enables debonding on demand specifically for coating layers on wood. The debonding mechanism is triggered at temperatures of 160–170 °C and results in complete loss of adhesion, while having no negative impact on the coating during use. The effect can be applied on large substrates with ease. It can also be used site-specifically which leaves adhesion of non-primed areas fully intact. Additional mechanistic investigations show that decomposition of NC is observed mainly at the interface between primer and coating.
•Topcoat layers were removed from wooden substrates, using a primer made of nitrocellulose.•Before triggering the system, unimpaired adhesion was found. After triggering at 160-170 °C, the adhesion was reduced to a minimum.•The debonding mechanism was investigated by IR and microscopical analysis.•Based on this process, recycling procedures for high value wood can be implemented.
The development of a multifunctional wood wax oil-based coating holds significant importance in meeting demands for wood protection and enhanced longevity of wood materials. Nevertheless, a simple ...method of developing such an integrated coating that possesses excellent durability, ultraviolet (UV) resistance, water resistance, and environmental friendliness remains a significant obstacle. In this paper, stearoyl chloride-grafted cellulose nanocrystals (SCNCs) with excellent compatibility with wood wax oil (WWO) coatings were prepared by combining cellulose nanocrystals (CNCs) with stearoyl chloride through a one-step non-homogeneous esterification reaction. Nanocomposite coatings were prepared by a simple one-step ultrasonic miscibility method using SCNCs as modified functionalized fillers. The prepared SCNC-WWO wood coatings had high hardness (grade H), strong adhesion (class 0, with no peeling), high abrasion resistance, good UV resistance, high hydrophobicity (water contact angle of 116°), and good water resistance (maintainable for 1 day). In addition, SCNCs with gas barrier properties can effectively inhibit the release of pollutants within the coatings, making this composite coatings environmentally friendly. Therefore, SCNC-WWO can be used as a high-performance coating for substantial protection of wood in harsh environments, and the strategy for developing it provides insight into the preparation of multifunctional wood paint.
•The prepared fillers SCNCs have cellulose type I structure and excellent organic compatibility.•SCNC-WWO composite coatings can be successfully prepared by a one-step ultrasonic miscibility method.•SCNC-WWO wood coatings have excellent durability, UV and water resistance.•SCNC-WWO wood coatings have excellent gas barrier properties, making the coatings environmentally friendly.
Abstract
Transparent wood (TW)‐based materials have increasingly become the focus of researchers worldwide owing to their superior physico‐chemical‐optical properties, sustainable nature, as well as ...the fact that they are highly accommodating frameworks that can act as building blocks to readily explore a vast range of potential functionalities, holding great potential to displace glass and plastics in their various respective applications. The integration of multiple functionalities into TW has been undertaken to fulfill the demands of prospective sophisticated applications through the utilization of functional fillers or coatings. Herein, the up‐to‐date foundational developments and reports concerning emergent TW composites and coatings from a perspective of fabrication‐functionality‐application are comprehensively summarized, with a particular focus on seven specific functionalities; i) solar control; ii) chromically‐responsive, iii) electrically‐conductive, iv) shape‐memory active; v) flame‐retardant; vi) electromagnetic interference shielding; and vii) aesthetics. The potential applications of TW with these functionalities are also discussed. Finally, the current challenge with TW is addressed, as well as the future developments required for eventual real‐world application.
Abstract
To address the issues of insufficient film smoothness, and flammability of aqueous polyurethane dispersions (PUD) prepared by adding matting agents, two hydrophilic chain extenders, ...dimethylolpropionic acid (DMPA) and sodium 2‐(2‐aminoethyl)amino ethanesulphonate (A95), were used to regulate the particle size of the emulsion while using FRC‐6 flame retardant as a small molecule chain extender to prepare a self‐matting and flame retardant PUD. Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscope, and atomic force microscopy were used to structurally characterize the latex films. The results showed that as the
R
‐value (NCO/OH molar ratio) and soft segment content decreased, the prepolymer viscosity increased, making it difficult to emulsify and reducing the glossiness of the film. Moreover, an initial increase in DMPA content led to a decrease in film glossiness, followed by an increase. Increasing the molar ratio of A95 sulfonic acid salt‐based chain extender to EDA affected the glossiness of the film, with a 2:8 molar ratio of A95: ethylenediamine (EDA) resulting in a glossiness of the film of 6.5%. The addition of reactive flame retardant diethyl bis (2‐hydroxyethyl) aminomethyl phosphonate (FRC‐6) increased the branching content in the prepolymer, improved the flame retardancy of the film, and reduced its glossiness. As a result, the self‐prepared PUD had a flat film with a glossiness as low as 6.0% and a flame retardancy rating of level 4.
