Functional and versatile superhydrophobic coatings via stoichiometric silanization

Superhydrophobic coatings have tremendous potential for applications in different fields and have been achieved commonly by increasing nanoscale roughness and lowering surface tension. Limited by the availability of either ideal nano-structural templates or simple fabrication procedures, the search of superhydrophobic coatings that are easy to manufacture and are robust in real-life applications remains challenging for both academia and industry. Herein, we report an unconventional protocol based on a single-step, stoichiometrically controlled reaction of long-chain organosilanes with water, which creates micro- to nano-scale hierarchical siloxane aggregates dispersible in industrial solvents (as the coating mixture). Excellent superhydrophobicity (ultrahigh water contact angle >170° and ultralow sliding angle <1°) has been attained on solid materials of various compositions and dimensions, by simply dipping into or spraying with the coating mixture. It has been demonstrated that these complete waterproof coatings hold excellent properties in terms of cost, scalability, robustness, and particularly the capability of encapsulating other functional materials (e.g. luminescent dyes).

Waste Plastic Sachet as Alternative Anti-Corrosion Filler for Iron Oxide in Resin Coatings

Iron oxides and similar inorganic compounds have served as anti-corrosion fillers for metal coatings. Environmental issues related to the mining of metallic fillers have stimulated interest in alternative fillers such as organic fillers. This paper explores the use of comminuted waste plastic sachets (WPS) as an anti-corrosion filler to resin-based metal coating. Mixture design of experiment was used to study the effect of iron oxide-WPS blends on the film thickness, viscosity, corrosion behavior, and water resistance of the coating. Results show that the film thickness was affected by the presence of iron oxide while the viscosity of the coating was affected by high loads of WPS. Among all coatings, the blend containing 25% iron oxide and 75% WPS produced the highest corrosion resistance. In conclusion, comminuted WPS provided additional corrosion resistance and could serve as an alternative anti-corrosion filler.

High-temperature wettability study of mineral waste added CaO–CaF2–SiO2 and CaO–TiO2–SiO2-based electrode coating for offshore welds

This paper investigates the high-temperature wettability property of the mineral waste red ochre added CaO–CaF2–SiO2 and CaO–TiO2–SiO2-based electrode coating mixture for offshore welding. The extreme vertices design method was applied to formulate 21 coating compositions. The pellets made from developed electrode coating compositions were exposed to a high temperature of 1250℃ on the substrate of super duplex stainless steel of 2507 grade. The molten flux has been characterized for contact angle, surface tension, adhesion energy and spreadability. The regression analysis has been used to estimate the effect of individual components and their interactions on the wettability property parameters. The developed regression models have been optimized using multiresponse optimization to achieve optimum flux composition. Structural analysis of flux mixture has been done using X-ray diffraction and Fourier transformation spectroscopy.

Effects of the Coating Mixture on the Penetration of Liquids into Paper

The pigment coating of paper is usually performed to enhance the physical properties of paper and its printability. The coating generally makes paper whiter, brighter and more opaque. The properties of the coated paper depend, among others, on the porous structure of the coating developed, which is determined by the pigments, binders and their reactions. The influence of the type and quantity of coating components and ink absorption into the coating layer was studied in this work. Printing ink penetration was measured using a Penetration Dynamic Analyser with an HVL module (High Viscous Liquid). The evenness of liquid penetration into paper was measured using a Penetration Dynamic Analyser with a PEA module (Print Evenness Analyser). Results obtained indicate that all three variables – coating pigment type, latex dose and ink type – may have an equally strong influence on liquid and ink penetration,and thus on print quality.

Sound absorbing properties of roller blind curtain fabrics

Roller blind fabrics are preferred and commonly used in home and office. In general, these fabrics are produced by coating the acrylic blended material, which is known by their ultraviolet properties, onto polyester woven fabrics. In this study, in order to characterize the sound insulation properties of roller blind fabrics, coating resin having different ratios of acrylic are applied onto different polyester woven structures. Sound absorption properties of these fabrics (front and back sides) are measured through dual microphone impedance tube and investigated by statistical analyses. Regression curves are obtained and optimum fabric properties on sound absorbing property have been suggested. As a result, acrylic content in coating material, fabric type, and viol structures occurred by coating process on the woven fabric are found as effective parameters on sound absorption properties of these fabrics. Increasing acrylic content in the resin up to 40% increases the sound absorbing value but further increasing this ratio yields sound reflection from the structure, in general. Optimum sound absorption and reflection values are provided with 40% acrylic rate in coating mixture.

Dust Removal Using Electrode-Plates Coated with Activated Carbon

The main purpose of this research work was to evaluate dust removal efficiencies using electrode plates coated with activated carbon in dust removal chamber. The experiments were performed with electrode-plates coated with activated carbon with black carbon and poly vinyl acetate (PVA) as binding agent. Methanol was added into the coating mixture for lowering the viscosity and at the same time helped the activated carbon (AC) pores not to be blocked by PVA. After coating the electrode surface, it was tested to collect dust in cylindrical chamber with and without power supply. In both case, AC coated electrode showed higher dust removal efficiencies compared to conventional aluminum electrode. Continuous test for PM10 dust control revealed that removal efficiency gradually increased with time passage, and as increasing the distance from inlet, the removal efficiency becomes stable. However, where the interval between electrodes was as short as 1cm, and also at the back of the chamber, “back discharge” effect was observed, and resolved easily by the elevation of humidity level. Volatile organic compounds (VOCs) were controlled successfully with the AC coating material so that it proved both particular and gaseous contaminants can be treated with this AC-coated electrostatic precipitator.*Corresponding author (Kwang Soo Kim): Daehwa-Dong 283, Goyangdae-Ro, Ilsanseo-Gu, Goyang-Si, Gyeonggi-Do, 411-712, Korea / [email protected] / Tel. + 82 31 9100 299 / Fax. +82 31 910 0291