Wear response and mechanical behaviour of silicone-based photoluminescent coatings (original) (raw)
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Tribology of water and oil repellent sol–gel coatings for optical applications
Wear, 2009
Oil and water repellent sol-gel silica coatings may be used to extend the use and lifetime of certain computer displays, optoelectronic devices, and optical components such as touch screens. Organic-inorganic coatings consisting of organically modified silica are an optimal class of materials to use for such applications as they are substantially more durable than conventional polymers while having low processing temperatures compatible with organics. This study is concerned with the characterization of wear-resistant coatings derived from polysiloxanes. Organically modified sol-gel silica coatings were deposited on soda-lime glass substrates by dip coating. Mechanical, surface, and tribological properties were investigated using nanoindentation, contact angle goniometry, stylus profilometry, and a reciprocating polishing wear test to determine wear rate by mass loss. The average hardness of films was found to be 1.2 GPa and independent of curing times above 30 min at 150 • C. In polishing wear, failure was caused by gradual abrasive wear through the depth of the coating. Wear rate was found to be independent of curing times above 30 min at 150 • C. The development of these coatings will contribute to the rational design of the next generation of transparent overlays and displays.
Polymeric and ceramic silicon-based coatings – a review
Journal of materials chemistry. A, Materials for energy and sustainability, 2019
Silicon-based polymers are outstanding materials for coating applications. These compounds have excellent properties, such as strong adhesion to most substrates, and high chemical, thermal and UV resistance. Additionally, they can be converted into ceramic materials (polymer-derived ceramics) by a heat treatment and, in some cases, by chemical reactions or radiation. Hence, ceramic coatings can be obtained after deposition of the polymers by simple lacquer techniques. The properties and composition of polymeric and ceramic coatings can be changed by tailoring the chemical structure of the precursors or by the addition of fillers. This enables the preparation of coatings with a great variety of properties for different applications. In this review paper, the main aspects of the use of silicon polymers for coatings are elucidated. The advantages and disadvantages of these materials, and the processing methods developed are discussed. Finally, a summary of the applications and the prospects for future research are presented. oxidation is limited. In contrast, ceramic coatings combine a high hardness, wear and temperature resistance, with corrosion and oxidation stability. The main drawbacks of this type of coatings, though, are the higher processing costs compared to polymeric and metallic coatings, and the characteristic brittleness of ceramics. Ultimately, the choice of coating material will depend on the desired properties, environmental conditions during application and processing, on the compatibility with the substrate, and on material and processing costs. Considering these aspects, silicon-based polymers standout as coating material. Coatings based on these compounds have a higher thermal stability and chemical resistance when compared to most organic coatings. 1
Journal of Composites Science, 2020
This study aims to evaluate the synergical effects of SiO2 nanoparticles (nano-SiO2) and organic photostabilizers (Tinuvin 384 (T384) and Tinuvin 292 (T292)) on the weathering resistance of acrylic polyurethane coating. Data obtained from infrared (IR), field emission scanning electron microscopy (FESEM), and weight loss of coatings (before and after aging test), suggest that the SiO2 nanoparticles play a dual role, as both reinforcer and UV absorber, thus improving effectively both the mechanical properties and the weathering resistance of polyurethane acrylic coatings. The nanocomposite coating containing 2 wt % nano-SiO2, 2 wt % T384, and 1 wt % T292 exhibits excellent weathering and abrasion resistances, offering a durable outdoor application.
UV-LED as a New Emerging Tool for Curable Polyurethane Acrylate Hydrophobic Coating
Polymers
The elimination of mercury, low energy consumption, and low heat make the ultraviolet light-emitting diode (UV-LED) system emerge as a promising alternative to conventional UV-mercury radiation coating. Hence, a series of hydrophobic coatings based on urethane acrylate oligomer and fluorinated monomer via UV-LED photopolymerisation was designed in this paper. The presence of fluorine component at 1160 cm−1, 1235 cm−1, and 1296 cm−1 was confirmed by Fourier Transform Infra-Red spectroscopy. A considerably high degree C=C conversion (96–98%) and gel fraction (95–93%) verified the application of UV-LED as a new technique in radiation coating. It is well-accepted that fluorinated monomer can change the surface wettability as the water contact angle of the coating evolved from 88.4° to 121.2°, which, in turn, reduced its surface free energy by 70.5%. Hence, the hydrophobicity of the coating was governed by the migration of the fluorine component to the coating surface as validated by sca...
Preparation and characterisation of phenyl silicone‐acrylic polyol coatings
Pigment & Resin Technology, 2010
Purpose -The paper's aim is to investigate improvement of strength and adhesion of silicone-acrylic hybrid systems. Design/methodology/approach -The presence of Si-C bonds in phenyl silicone should be able to improve strength, adhesion and thermal properties of phenyl silicone-acrylic polyol coating. Different weight ratios of phenyl silicone and acrylic polyol resins were blended in order to obtain the composition for optimum strength, adhesion and thermal properties. Strength was evaluated using an impact resistance tester. Coating adhesion was studied by measuring the contact angle and performing cross hatch cutting. The thermal properties were studied using differential scanning calorimetry. Findings -Blending phenyl silicone intermediate resin with acrylic polyol resin showed significant improvement in strength and adhesion properties compared to pure acrylic polyol resin. This paper shows that the composition of such coatings influences the glass transition temperature (T g ), which in turn affects the strength and adhesion properties of the coatings. The coating consisting of 30 per cent silicone resin and 70 per cent acrylic resin showed good adhesion and impact resistance properties on cold roll mild steel panels.
Journal of Coatings Technology and Research, 2016
Many coatings properties such as mechanical, electrical, and ultra violet (UV) resistance are greatly enhanced by the addition of nanoparticles, which can potentially increase the use of nanocoatings for many outdoor applications. However, because polymers used in all coatings are susceptible to degradation by weathering, nanoparticles in a coating may be brought to the surface and released into the environment during the life cycle of a nanocoating. Therefore, the goal of this study is to investigate the process and mechanism of surface degradation and potential particle release from a commercial nanosilica/polyurethane coating under accelerated UV exposure. Recent research at the National Institute of Standards and Technology (NIST) has shown that the matrix in an epoxy nanocomposite undergoes photodegradation during exposure to UV radiation, resulting in surface accumulation of nanoparticles and subsequent release from the composite. In this study, specimens of a commercial polyurethane (PU) coating, to which a 5 mass % surface treated silica nanoparticles solution was added, were exposed to well-controlled, accelerated UV environments. The nanocoating surface morphological changes and surface accumulation of nanoparticles as a function of UV exposure were measured, along with chemical change and mass loss using a variety of techniques. Particles from the surface of the coating were collected using a simulated rain process developed at NIST, and the collected runoff specimens were measured using inductively coupled plasma-optical emission spectroscopy (ICP-OES) to determine the amount of silicon released from the nanocoatings. The results demonstrated that the added silica nanoparticle solution decreased the photodegradation rate (i.e., stabilization) of the commercial PU nanocoating. Although the degradation was slower than the previous nanosilica epoxy model system, the degradation of the PU matrix resulted in accumulation of silica nanoparticles on the nanocoating surface and release to the environment by simulated rain. These experimental data are valuable for developing models to predict the long-term release of nanosilica from commercial PU nanocoatings used outdoors and, therefore, are essential for assessing the health and environmental risks during the service life of exterior PU nanocoatings.
Materials Chemistry and Physics, 2010
Transparent UV-curable nano-composite coatings consisting of nano-sized SiO 2 and acrylate resin have been developed to improve the abrasion resistance of organic polymers. The nano-sized SiO 2 particles were surface-modified using various amounts of 3-methacryloxypropyltrimethoxysilane (MEMO). The MEMO concentration effects on the rheological behaviors, optical and abrasion resistance properties were investigated using a viscometer, FTIR, UV-visible spectrophotometer. The results showed that the steric-hinderance established on the nano-sized SiO 2 surface due to the grafted MEMO can effectively improve the dispersibility of nano-sized SiO 2 in acrylate suspensions. The MEMO-modified nano-sized SiO 2 in acrylate solutions at low and high solid concentrations exhibited Newtonian and shear thinning flow behaviors, respectively. Moreover, the maximum solid concentration was estimated to be 0.23. As the MEMO/SiO 2 weight ratio increases from 0.2 to above 0.6, the abrasion resistance was significantly improved and the pencil hardness increased from 4H to 6H, which may be attributed to the complete MEMO coverage on the SiO 2 surface, thereby enhancing the dispersion, compatibility, and cross-linking density between the MEMO-modified SiO 2 particles and acrylate resin.
Preparation of Silica Powder in Epoxy Resin Wear-Resistant Coating
Silicon powders possess good thermal stability and rub resistance and can be used as the filler of high temperature wear-resistant coating; it can possess good wettability and dispersibility in the organic polymer by surface modification of silane coupling agent. Organic silicon has good thermal stability, which can modify the frangibility and thermal stability of epoxy resin. A certain proportion of modified silica powder, curing agent and additives were dispersed to modified epoxy resin can compound wear-resistant coating. The results show that: the modification effect can be the best if the dosage of silane coupling agent is 1.5% of silicon powder. If the methyl triethoxy silane is 50 phr and modified silica powder is 200 phr, then various performances of coating tend to be the best.
Zero VOC and High Solid Content Photocured Siliconized Coatings
This article explores the possibility of using telechelic silicones in traditional acrylate-based UVC compositions. An in-depth analysis of cure kinetics of UVCs was conducted using Raman spectroscopic techniques. The surface morphology of the UVC coated substrate was studied with atomic force microscopy (AFM). The hardness and modulus of the siliconized UVC was determined by nanoindentation techniques. Moreover, instrumented nanoscratch tests helped in understanding the adhesive and cohesive modes of failures in siliconized UVC. Attempts have also been made to understand the wear characteristics of the siliconized surface. It is expected that this article will provide readers a good understanding on the properties of siliconized UVC formulations.
Study on the Wettability and Optical Properties of Polydimethylsiloxane-SiO2 Nano-composite Surfaces
International Journal of Advanced Design and Manufacturing Technology, 2020
In this paper, the effects of different weight percentages of silica nano-particles on the wettability and optical properties of polymer based surfaces were investigated. The Polydimethylsiloxane (PDMS)-SiO2 nano-composites containing 0.5, 1, 2, 3 and 4 wt% silica were prepared and coated on the fabric surfaces by immersion technique at the ambient conditions. Then, the characterization of nano-composite coated samples was carried out by water contact angle technique, scanning electron and atomic force microscopes and diffuse reflectance spectroscopy. It was found that increasing the silica content caused to increase the water contact angle of sample to 158° which results in an improvement in the water repellency property. This can be due to the aggregation of silica nano-particles which led to higher surface roughness of sample. The AFM and SEM images validated the results of surface roughness. However, Silica-PDMS composite coated sample exhibited a lower transmittance value (57%) in comparison to the uncoated sample (90%). This can be ascribed to the light scattering by silica nano-particles.