The Synergistic Effects of Sio2 Nanoparticles and Organic Photostabilizers for Enhanced Weathering Resistance of Acrylic Polyurethane Coating (original) (raw)
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Applied Surface Science, 2011
Nano-filled polyurethane coatings were prepared by incorporation of various amounts of untreated and amino propyltrimethoxy silane (APS) treated TiO 2 nanoparticles. TEM and AFM techniques were employed to evaluate dispersion of nanoparticles and surface morphology of the coating, respectively. TEM observations revealed that the APS treated nanoparticles have a better dispersion and smaller agglomeration, compared with their untreated counterparts. AFM images revealed that, surface roughness of the coatings increased with increasing of nanoparticles content, however, at equal level of loadings; coatings containing untreated nanoparticles showed a higher surface roughness.
Materials Chemistry and Physics, 2020
nanoparticles improved conversion performance of isocyanate groups, gel fraction, swelling degree and relative hardness of the coating. Accelerated weathering test indicates that, after 36 cycles of test, the nanocomposite coating was degraded with the formation of several holes on the coating surface and the recorded weight loss was 9.1%. For the neat coating, the formation of various large holes of dimension ranging from 20 nm to several μm on the surface was observed and the weight loss is measured to be higher (12.7%) in the same conditions. Nano RHA-SiO 2 possibly play a dual role: i) UV protector and ii) nanofiller helping to prevent the invasion of aging agents.
Effect of titania and zinc oxide particles on acrylic polyurethane coating performance
Progress in Organic Coatings, 2011
The outer environment, especially UV portion of solar radiation and water (in the form of moisture or rain) has an adverse effect on the surface appearance of heat-treated wood. Exposure to UV triggers the chain scission reactions which change the intrinsic properties of heat-treated wood and discoloration of wood surface. Repeated temperature and humidity variations cause swelling and shrinking of wood surface, which consequently creates cracks and fissures exposing wood's sub superficial layers to atmospheric agents. Therefore, wood industries move towards the development of coatings in order to protect the heat-treated wood while retaining wood's natural look. Water based acrylic polyurethane coatings are highly efficient, non toxic and durable coatings with upgraded film properties. In this study, an attempt is made to improve the performance of these coatings by incorporating natural antioxidant (bark extract) and inorganic UV absorbers (nano and micro titania and nano zinc oxide) into the coatings. The main objectives of this study are to investigate the wetting and penetration characteristic of these new coatings on the wood surface and to study coating thickness variation with weathering time. The Sessile-drop method and fluorescence microscope are used for this investigation. The wettability of different coatings applied to heat-treated jack pine early wood and late wood is compared. The results show that there is a significant difference between the contact angle of early wood and late wood for acrylic polyurethane coating containing titania micro particles. The contact angle between water and coated wood surface reveals that the degree of orientation of the coating materials increases as the weathering time increases. The penetration characteristics of all the three coatings are found to be very poor. In addition, the relationship between the coating thickness and the UV exposure time are studied for three different water based acrylic polyurethane coatings. It is found that the coating thickness decreases with increasing weathering time and a tissue deformation beneath the coating surface takes place during weathering.
Journal of Coatings Technology and Research, 2011
The effect of alumina and silica nanoparticles on mechanical, optical, and thermal properties of UV-waterborne nanocomposite coatings was investigated. The addition of nanoalumina and nanosilica was shown to decrease the hardness because of nanoparticle aggregation. In comparison to the neat coating and despite the presence of aggregates, the scratch resistance of nanocomposite coatings was significantly improved. As expected, the gloss of UV-waterborne coatings was reduced following the addition of nanoparticles due to an increase of the surface roughness. Alumina and silica nanoparticles were found to enhance the glass transition temperature of PUA nanocomposite coatings by hindering the mobility of macromolecular chains at the interface around the nanoparticles. Finally, the interest and efficiency of grafting trialkoxysilanes was demonstrated with the study of nanosilica behavior. Not only was the dispersion of nanosilica enhanced following trialkoxysilanes grafting onto silica nanoparticles, but also the scratch resistance and the adhesion of UV-waterborne coatings containing nanosilica markedly increased even with 1 wt% content. Silica which is recommended in the wooden furniture and kitchen cabinet manufacturing industry as nano-reinforcement provides improved properties well suited in surface coating applications to efficiently protect surface of wood substrates.
Acid and alkali resistance of Acrylic polyurethane/R-SiO2 nanocomposite coating
Vietnam Journal of Chemistry, 2020
The purpose of this study is to assess the influence of R-SiO2 nanoparticles on acid and alkali resistance of acrylic polyurethane coating. The resistance of the coatings with and without 2.5 wt.% R-SiO2 nanoparticles in 5 % HCl solution and 5 % NaOH solution was investigated by monitoring the variations in functional groups of the coatings using IR spectroscopic analysis and the changes in their morphology using FE-SEM analysis, as well as their weight loss analysis. The results showed that R-SiO2 nanoparticles at content of 2.5 wt.% significantly increased the acid and alkali resistance of acrylic polyurethane coating. After 20 days of immersion in 5 % HCl solution and 5 % NaOH solution, the nanocomposite coating containing 2.5 % R-SiO2 nanoparticles changed negligibly with a weight loss of about 1 % while the coating not containing R-SiO2 nanoparticles was deformed seriously with a weight loss of about 3 %.
UV curable polyester‐based polyurethane acrylate nanocoating
Pigment & Resin Technology, 2010
Purpose-The paper's aim is to synthesise ultraviolet (UV) curable polyurethane acrylate based on polyester polyol and to study change in its mechanical, chemical, optical and weather resistance properties with varying amount of nanosilica. It also seeks to determine its optimum loading levels for property maximisation. Design/methodology/approach-New UV curable polyurethane acrylate has been synthesised using polyester polyol, blend of isophorone diisocyanate and toluene diisocyanate and hydroxyl ethyl acrylate. This resin was incorporated with nanosilica (1-3 per cent) on the basis of total solids. The newly synthesised material was characterised by fourier transform infrared spectroscopy, gel permeation chromatography, X-ray diffraction and scanning electron microscopy. The mechanical, chemical and optical properties of the coating films were studied and compared. Findings-The hardness, tensile strength and abrasion resistance show significant enhancement with increasing amount of nanosilica. It is also found that UV cured polyurethane acrylate nanocoating exhibited improved weather resistance. The optimum concentration of nanosilica for better performance is found to be 3 per cent of total solids. The improvement is the result of inherent nature of nanosilica. Research limitations/implications-Nanosilica used in present context is having 10 nm mean diameter and near about 600 m 2 /g surface area. Nanosilica having different particle size, surface area and surface modification can be used to improve more specific properties. Practical implications-Addition of nanosilica particles to polyurethane acrylate coating is a simple and inexpensive method resulting in phenomenal increase in properties. Originality/value-The new organic-inorganic hybrid nanocoating with improved weather resistance was synthesised. These coatings could find applications in demanding fields such as automotive topcoats.
Weathering Resistance of Waterborne Polyurethane Coatings Reinforced with Silica from Rice Husk Ash
Anais da Academia Brasileira de Ciências, 2019
Waterborne polyurethanes (WPUs) are interesting materials for coatings when compared to solvent-based polyurethanes, once that reducing the concentration of volatile organic compounds that are harmful for human health and the environment. however, the WPU has low weathering resistance. In order to improve this behavior among others properties, inorganic fillers has been added in these systems. SiO 2 particles from various sources, mainly, from agro-industrial waste, as rice husk has attracted the scientific and technological interest. In this study, the accelerated weathering essay was performed in waterborne polyurethane (WPU)/ silica (from rice husk ash) composites in order to evaluate the thermal and physical changes in these materials. These composites were prepared by two distinct methods: in situ polymerization and blending method. The highest resistance to thermal degradation and to accelerated weathering was reached with WPU/silica composites obtained by blending method due the interactions between SiO 2 particles and the polymer matrices. Blending method for preparation WPU/silica composites proved to be a simpler and faster method, with no drawback for large scale application.
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.
Progress in Organic Coatings
In this work the properties of UV curable coatings were improved modifying the polymeric matrix adding properly functionalized silica inorganic nanoparticles. Mild steel sheets were used as substrate. Pre-formed silica nanoparticles, prepared by sol–gel chemistry from methyltriethoxysilane (MTES) and methacryloxypropyltrimethoxysilane (MPTMS) precursors, were dispersed into UV curable acrylic oligomers: by irradiation a polymeric matrix embedding the nanoparticles was obtained. Unfilled UV cured coatings were also produced for comparison. The DSC measurements revealed different thermal stabilities among the samples, depending on the presence of the functionalized nanoparticles. The barrier properties (investigated by means of electrochemical impedance spectroscopy, EIS) were demonstrated to be strongly affected by the presence of the nanoparticles. In particular, a proper functionalization of the silica nanoparticles leads to noticeable improvement of the barrier properties of the c...
The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight
Journal of Visualized Experiments, 2016
Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, building and food industries, amongst others. Polyester and coatings containing both polyester and silica nanoparticles (SiO 2 NPs) have been widely used to protect steel substrata from corrosion. In this study, we utilized X-ray photoelectron spectroscopy, attenuated total reflection infrared micro-spectroscopy, water contact angle measurements, optical profiling and atomic force microscopy to provide an insight into how exposure to sunlight can cause changes in the micro-and nanoscale integrity of the coatings. No significant change in surface microtopography was detected using optical profilometry, however, statistically significant nanoscale changes to the surface were detected using atomic force microscopy. Analysis of the X-ray photoelectron spectroscopy and attenuated total reflection infrared micro-spectroscopy data revealed that degradation of the ester groups had occurred through exposure to ultraviolet light to form COO·,-H 2 C·,-O·,-CO· radicals. During the degradation process, CO and CO 2 were also produced.