Studying the Influence of Mica Particle Size on the Properties of Epoxy Acrylate/Mica Composite Coatings through Reducing Mica Particle Size by the Ball-Milled Method

In this work, a series of epoxy acrylate (EA)/mica composite coatings were synthesized through introducing mica powders of different particle size into epoxy acrylate coatings and using an ultraviolet (UV) curing technique to investigate the influence of mica particle size on the coatings. Mica powders of different particle sizes were obtained by ball-milling for 4, 8, 12, 16, and 20 h with a planetary high-energy ball mill. The particle size and morphologies of ball-milled mica powders were characterized by laser particle size analyzer and scanning electron microscopy (SEM). The results indicated that planetary ball-milling reduced the particle size of mica powders effectively. Mica powders that were un-ball-milled and ball-milled were added into the epoxy acrylate matrix by a blending method to synthesize the organic-inorganic UV curable coatings. The optical photographs of the coatings showed greater stability of liquid mixtures with smaller particle size fillers. The chemical structures of EA/mica composite coatings were investigated by Fourier transform infrared spectroscopy (FTIR), and the conversion rate of C=C bonds was calculated. The results indicated that the C=C conversion of coatings with mica powders of smaller particle sizes was higher. Tests of mechanical properties and tests using electrochemical impedance spectroscopy (EIS) showed that pencil hardness, impact resistance, and coating resistance were improved due to the reduction of mica powders particle size.

Fabrication of Transparent and Conductive SWCNT/SiO2 Composite Thin-Film by Photo-Irradiation of Molecular Precursor Films

A single-walled carbon nanotube (SWCNT)-silica composite thin film on a quartz glass was formed by ultraviolet irradiation (20–40 °C) onto a spin-coated precursor film. With 7.4 mass% SWCNTs, the electrical resistivity reached 7.7 × 10−3 Ω·cm after UV-irradiation. The transmittance was >80% at 178–2600 nm, and 79%–73% at 220–352 nm. Heat treatment increased the transparency and pencil hardness, without affecting the low electrical resistivity. Raman spectroscopy and microscopic analyses revealed the excellent film morphology with good SWCNT dispersal. The low refractive index (1.49) and haze value (<1.5%) are invaluable for transparent windows for novel optoelectronic devices.

UV-Curing of Novel Tri-functional Melamine-phosphate Oligomer: An Effect of Coating With Polyurethane Acrylate Towards Mechanical, Thermal And Flame Retardant Properties

A novel melamine-phosphate trifunctional acrylate MPTO) was successfully synthesized via simple cyclization of hexamethylolmelamine (HMM) with phosphorous oxychloride (POCl3) followed by addition reaction of hydroxyethylmethacrylate (HEMA). The molecular structure of MPTO was identified by FTIR and 1H-NMR, 13C-NMR, and GC-MS spectra. The synthesized MPTO oligomer was impregnated with polyurethane acrylate to make the various formulation of UV-cured coatings. The polyurethanes-MPTO oligomers were coated on wood and galvanized steel panels. The properties of UV-cured PU-MPTO were studied by differential scanning calorimeter (DSC), while their crystallinity by X-ray diffraction analysis (XRD). The thermo-gravimetric analysis (TGA) exhibited a high char yield of 18.4% at 800 °C. Moreover, coating films show prominent flame retardancy with UL-94 V-0 rating and maximum limiting index value (LOI) values of 34.8%, which are much higher than the common polyurethane coatings. The polyurethane coatings cured with MPTO exhibited excellent mechanical properties were estimated various tests such as adhesion, pencil hardness, solvent resistance, flexibility, and corrosion test. The coating performance revealed that MPTO improves the mechanical, thermal, and flame retardant properties because their unique structure contains melamine-phosphate moiety and long aliphatic chains of an acrylate ester. These high-performance melamine-based UV-curable coatings are promising for extensive applications.

Rubber Seed Oil-Based UV-Curable Polyurethane Acrylate Resins for Digital Light Processing (DLP) 3D Printing

Novel UV-curable polyurethane acrylate (PUA) resins were developed from rubber seed oil (RSO). Firstly, hydroxylated rubber seed oil (HRSO) was prepared via an alcoholysis reaction of RSO with glycerol, and then HRSO was reacted with isophorone diisocyanate (IPDI) and hydroxyethyl acrylate (HEA) to produce the RSO-based PUA (RSO-PUA) oligomer. FT-IR and 1H NMR spectra collectively revealed that the obtained RSO-PUA was successfully synthesized, and the calculated C=C functionality of oligomer was 2.27 per fatty acid. Subsequently, a series of UV-curable resins were prepared and their ultimate properties, as well as UV-curing kinetics, were investigated. Notably, the UV-cured materials with 40% trimethylolpropane triacrylate (TMPTA) displayed a tensile strength of 11.7 MPa, an adhesion of 2 grade, a pencil hardness of 3H, a flexibility of 2 mm, and a glass transition temperature up to 109.4 °C. Finally, the optimal resin was used for digital light processing (DLP) 3D printing. The critical exposure energy of RSO-PUA (15.20 mJ/cm2) was lower than a commercial resin. In general, this work offered a simple method to prepare woody plant oil-based high-performance PUA resins that could be applied in the 3D printing industry.

A Study on Microwave Exposure Effects on Surface Coating Properties of Linden (Tilia cordata) and Spruce (Picea abies) Woods

The quality performance of surface coatings are evaluated with emphasis on Microwave (Mw) irradiation, effects on both wood and oil modified alkyd-based varnish, separately. The surface pencil film hardness value of 2B (5 in metric) found for neat varnish coated linden and spruce control samples. It appears Mw exposure on both woods and varnish were effective for further increasing pencil hardness which are about 4 and 5 unit higher than controls. It is also noticeable that a clear improvement for cross-cut (adhesion) properties were realized with Mw treated varnish coated linden woods. Although cold liquid resistance of coating evaluations have conducted with 11 liquids, but coated surfaces were showed the lowest resistance, assessed grade 1 (considerably changes) for five of these liquids (juice, milk, ketchup, lemon juice, cola) regardless of conditions or wood species. Therefore, results revealed some level correlation between Mw conditions and wood samples for six of the cold liquids involved in the examination. Mw treated spruce samples usually show 1 to 2 unit higher olive oil, vinegar, mayonnaise, ethyl alcohol resistance while no any improvement found for coffee and mineral water. Linden samples usually show 1 to 3 unit improving (higher) resistance against all these six cold liquids, regardless of Mw conditions. It is important to note that all Mw treated and varnish applied wood species subjected to olive oil, mayonnaise and ethyl alcohol show very high resistant properties (graded 4 and 5). Similar results are also realized with applying Mw irradiated vanish to both wood species. These variations and changes could be results of chemical structural changes, including cross-linking by esterification and etherification, promoted by Mw irradiation.

Transparent and Hard Siloxane Based Hybrid UV-Curable Coating Materials with Amphiphobic Properties

In this study, highly transparent siloxane-based hybrid UV-curable coating materials were prepared using (acryloxypropyl)methylsiloxane monomer (APMS), a thiol-ene monomer, with benzoin ethyl ether. For the thiol-ene monomer, either pentaerythritol tetrakis(3-mercaptopropionate) (PETTMP) or trimethylolpropane tris(3-mercaptopropionate) (TMPTMP) was used. The siloxane-based hybrid coating materials were highly transparent and hard (pencil hardness of 6–7H). The materials were also amphiphobic, with a water static contact angle of 92–100° and an oil contact angle of 46–63°, when prepared with a high siloxane-monomer-to-PETTMP/TMPTMP ratio. In general, both hybrid coating materials exhibited improved oleophobicity, high hardness, and surface smoothness with increasing siloxane content, although the TMPTMP-based hybrid coating films exhibited slightly higher oleophobicity (lower hydrophobicity) and a smoother surface than the PETTMP-based hybrid coating films.

Preparation of High-Transparency, Superhydrophilic Visible Photo-Induced Photocatalytic Film via a Rapid Plasma-Modification Process

In this study, different amounts of SiO2 nanoparticles (7 nm) were added to simultaneously reach high transmittance, high hardness, and high adhesion for TiO2 film prepared by the sol–gel method and coated on glass through a dip-coating technique. For the film to achieve self-cleaning, anti-fogging, superhydrophilicity, and visible photo-induced photocatalysis, TiO2-SiO2 film was modified via a rapid microwave plasma-nitridation process for efficient N-doping by various N2-containing gases (N2, N2/Ar/O2, N2/Ar). Through nitrogen plasma, the content of N atom reached 1.3% with the ratio of O/Ti atom being 2.04. The surface of the thin films was smooth, homogeneous, and did not crack, demonstrated by the root mean square (RMS) roughness of film surface being 3.29–3.94 nm. In addition, the films were composed of nanoparticles smaller than 10 nm, with a thickness of about 100 nm, as well as the crystal phase of the thin film being anatase. After the plasma-nitridation process, the visible-light transmittance of N-doped TiO2-SiO2 films was 89.7% (clean glass = 90.1%). Moreover, the anti-fogging ability was excellent (contact angle < 5°) even without light irradiation. The degradation of methylene blue showed that the photocatalytic performance of N-doped TiO2-SiO2 films was apparently superior to that of unmodified films under visible-light irradiation. Moreover, the pencil hardness and adhesion rating test of the thin films were 7H and 5B, respectively, indicating that the obtained coatings had great mechanical stability.

Enhancement of Anticorrosive Performance of Renewable Cardanol Based Polyurethane Coatings by Incorporating Magnetic Hydroxyapatite Nanoparticles

The present investigation demonstrates renewable cardanol based polyol for the formulation of nanocomposite polyurethane (PU) coatings. The functional and structural features of cardanol polyol and nanoparticles were studied by FT-IR and 1H NMR spectroscopic techniques. The magnetic hydroxyapatite nanoparticles (MHAP) were dispersed in PU formulations to develop nanocomposite anticorrosive coatings. The amount of MHAP in PU formulations was varied from 1-5%, increase the percentage of MHAP increases the anticorrosive performance as examined by immersion and electrochemical methods. The nanocomposite PU coatings shows good coating properties viz., gloss, pencil hardness, flexibility, cross-cut adhesion and chemical resistance. Additionally, the coatings also studied for surface morphology, wetting, and thermal properties by scanning electron microscope (SEM), contact angle, and thermogravimetric analysis (TGA), respectively. The hydrophobic nature of PU coatings increased by addition of MHAP and optimum result (1050) was observed in 3% loading. The developed coatings revealed hydrophobic nature with excellent anticorrosive performance.

Deep-Ultraviolet Transparent Conductive MWCNT/SiO2 Composite Thin Film Fabricated by UV Irradiation at Ambient Temperature onto Spin-Coated Molecular Precursor Film

Deep-ultraviolet (DUV) light-transparent conductive composite thin films, consisting of dispersed multiwalled carbon nanotubes (MWCNTs) and SiO2 matrix composites, were fabricated on a quartz glass substrate. Transparent and well-adhered amorphous thin films, with a thickness of 220 nm, were obtained by weak ultraviolet (UV) irradiation (4 mW cm−2 at 254 nm) for more than 6 h at 20−40 °C onto the precursor films, which were obtained by spin coating with a mixed solution of MWCNT in water and Si(IV) complex in ethanol. The electrical resistivity of MWCNT/SiO2 composite thin film is 0.7 Ω·cm, and transmittance in the wavelength region from DUV to visible light is higher than 80%. The MWCNT/SiO2 composite thin film showed scratch resistance at pencil hardness of 8H. Importantly, the resistivity of the MWCNT/SiO2 composite thin film was maintained at the original level even after heat treatment at 500 °C for 1 h. It was observed that the heat treatment of the composite thin film improved durability against both aqueous solutions involving a strong acid (HCl) and a strong base (NaOH).

Polyesteramides Based on Linseed and Safflower Oils for Protective Coatings

Polyesteramide resins were obtained and evaluated as vehicles and the variations of film performance in relation to the amide linkage were studied. Treatment of either linseed or safflower oils with diethanolamine with catalytic amounts of alkali metal alkoxide under relatively mild conditions led to a substantially complete conversion to N,N-(hydroxyethyl) linseed amide (HELA) and N,N-(hydroxyethyl) safflower amide (HESA). Polymerization of the polyols with diadipyl aromatic amines (aniline, p-toluidine, p-aminophenol and p-aminobenzoic acid) was carried out to yield polyesteramide derivatives having interesting surface coating properties. Such a substitution was claimed to give much harder, tougher, more flexible films with excellent chemical resistance in comparison with alkyd resins of similar oil length. The study includes stoving films mechanical evaluation as gloss percent at 60ºC, adhesion, impact, pencil hardness and bending tests using mild steel plates. The films also possess excellent impact resistance, high scratch hardness values, excellent bending test and good adhesion.