Water-soluble Coatings Research Articles

Roles of water-soluble aerosol coatings for the enhanced radiative absorption of black carbon over south asia and the northern indian ocean

Black Carbon (BC), formed by incomplete combustion, absorbs solar radiation and heats the atmosphere. We investigated the enhancement in optical absorption of BC due to coatings of water-soluble (WS) species in the polluted South Asian atmosphere. The BC Mass Absorption Cross-section (MAC; 678 nm) was estimated before and after removal of the WS components. Wintertime samples were collected from three South Asian receptor observatories intercepting large-footprint outflow: Bangladesh Climate Observatory Bhola (BCOB; integrating outflow of the Indo-Gangetic Plain), Maldives Climate Observatories at Hanimaadhoo (MCOH) and at Gan (MCOG), both reflecting outflow from the South Asian region. The ambient MAC observed at BCOB, MCOH and MCOG were 4.2 ± 1.4, 7.9 ± 1.9 and 7.1 ± 1.5 m2 g−1, respectively.The average enhancement of the BC MAC due to WS coatings (i.e., ws-EMAC) was identical at all three sites (1.6 ± 0.5) indicating that the anthropogenic aerosols had already evolved to a fully coated morphology at BCOB and/or that subsequent aging involved two compensating evolution processes of the coating. Inspecting the key coating component sulfate; the sulfate-to-BC ratio increased threefold when transitioning from BCOB to MCOH and by about 1.5 times from BCOB to MCOG. Conversely, both WS organic carbon (WSOC)/BC and water-insoluble OC (WIOC)/BC ratios declined with distance: WSOC/BC diminished by 84 % from BCOB to MCOH and by 80 % from BCOB to MCOG, while WIOC/BC dropped by about 63 % and 59 %, respectively. Such declines in WSOC and WIOC reflect a combination of photochemical oxidation and more efficient washout of OC compared to BC. The observed changes in the SO42−/BC and WSOC/BC ratios across South Asia highlight the significant impact of aerosol composition on the optical properties of Black Carbon (BC). These findings emphasize the need for detailed studies on aerosol composition to improve climate models and develop effective strategies for reducing the impact of anthropogenic aerosols on the climate.

Preparation and properties of water-soluble coatings resistant to scratching on the surface of nuclear cladding

As the second barrier of radioactivity in the reactor core, Zr alloy nuclear cladding tubes are easily to be scratched by the fixed grid during assembly process. In order to protect them from possible damage during their insertion through the skeleton, it is proposed to use water-soluble coatings with excellent scratch resistance to protect nuclear cladding tubes, and then wash away the coating to prevent the impeding the normal operation of the assembly. In this study, polyacrylate emulsion, neutralizer and filler were used to synthesize the coating. The chemical composition, thermal stability and hydrophilic performance of the coating were analysed by Fourier Transform Infrared Spectroscopy (FT-IR), thermal gravimetric analysis (TGA) and water contact angle (WCA) respectively. TGA analysis showed that the weight loss rate of the coating was less than 10 % at 200 °C, indicating the good thermal stability of coating at 200 °C. The water contact Angle of the coating was reduced to 32.78°, indicating that the coating had good hydrophilicity. Scanning electron microscopy displayed that the micro-structure of coating was dense, which was one reason of the good scratching resistant. By adjusting the curing conditions, the optimized preparation parameters of the coating were obtained. When the curing temperature was 90 °C and the curing time was 30 min, the coating had more optimized scratch resistance and water solubility.

Mechanical and physical assessment of epoxy, mineral, solvent-based, and water-soluble coating materials

This paper assesses the behavior of mineral, epoxy (EP), solvent, and water-soluble coatings when exposed to salt and regular water for 28 days. Also, it evaluates the pull-off adhesion strength of the same coating materials applied to concrete slabs saturated with oil and water and dried with two different processes: air-dried for 28 days and air-dried for 14 days plus 14 days in the oven at 70 °C. Properties such as carbonation, water absorption rate, pull-off adhesion strength were evaluated for all coatings, and tensile strength, Young’s modulus, and elongation percentage were calculated for mineral coatings. According to the results, the EP coating showed the best performance with the highest pull-off adhesion strength (2.55 MPa) and lowest absorption rate, about 0.02 ± 0.002 g/m2 day in saltwater and 0.03 ± 0.002 g/m2 day in regular water. In addition, EP coatings also presented the lowest carbonation rate and the highest suppress ratio. The excellent performance of epoxy coatings is mainly due to their low porosity and the ability to decrease chloride diffusion, making them better than other types of coatings investigated in this study.

ИССЛЕДОВАНИЕ ДИСПЕРГИРУЮЩЕГО ЭФФЕКТА ПОЛИМЕРНЫХ ПОВЕРХНОСТНО-АКТИВНЫХ ВЕЩЕСТВ В АКРИЛОВЫХ ДИСПЕРСИЯХ, ПРИМЕНЯЕМЫХ ДЛЯ ОКРАСКИ УСТЬЕВОЙ АРМАТУРЫ НЕФТЯНЫХ СКВАЖИН

Актуальность работы обусловлена необходимостью создания новых воднодисперсных лакокрасочных материалов с повышенным эксплуатационным ресурсом, согласно жёстким требованиям ПАО «НК «Роснефть» для защиты от атмосферной коррозии устьевой арматуры нефтяных скважин. В связи с ужесточением экологических требований во многих странах мира возросло использование воднодисперсных лакокрасочных материалов. Так, один из крупнейших производителей устьевой арматуры нефтяных скважин в Республике Казахстан – АО «Казнефтегазмаш» – принципиально использует для окраски своих изделий только воднодисперсные акриловые лакокрасочные материалы: грунтовку «Уникор-М» ТУ 2316-002-0-31953544-96 и краску «Акрэм-Металл» ТУ 2316-003-0-31953544-96. Однако основные российские нефте- и газодобывающие компании, в частности ПАО «НК «Роснефть», ПАО «Газпром» и др., в последнее время резко ужесточили требования к сроку защитного ресурса лакокрасочных покрытий. Так, согласно технологической инструкции ПАО «НК «Роснефть» № П2-05 ТИ-0002 «Антикоррозионная защита металлических конструкций на объектах нефтегазодобычи, нефтегазопереработки и нефтепродуктообеспечения компании», минимальный защитный ресурс лакокрасочных покрытий в зависимости от условий эксплуатации, составляет не менее 10 лет. А применяемые АО «Казнефтегазмаш» акриловые лакокрасочные материалы обеспечивают защитный ресурс покрытий не более 5 лет. Поэтому с учетом всего вышеперечисленного нами предпринята попытка увеличения защитного ресурса лакокрасочного покрытия путем получения более однородного распределения пигмента в полимерной матрице, за счет применения поверхностно-активных веществ. Целью работы являлось изучение влияния полимерных поверхностно-активных веществ на диспергирование пигмента (диоксида титана) в водной дисперсии акрилового полимера. Методы: компьютерно-оптическая микроскопия и математическое моделирование. Результаты и выводы. Представлены результаты исследования влияния полимерных поверхностно-активных веществ марки TEGO: Glide 100 (полиэфирсилоксановый сополимер) и Dispers715w (полиакрилат натрия), на диспергирование диоксида титана (марка R-02) в водной акриловой композиции. Показано, что Glide 100 и Dispers 715w при содержании в композиции от 0,25 до 0,5 г/дм3 улучшают диспергирование пигмента. Наиболее эффективной добавкой является Dispers 715w, при этом диаметр частиц пигмента уменьшается в два раза (с 8 до 4 мкм). Выведены уравнения, описывающие влияние содержания и вида поверхностно-активных веществ на диаметр частиц пигмента, и на их основе построены номограммы. Разработанные лакокрасочные материалы могут использоваться для окраски устьевой арматуры нефтяных скважин.

Cloud droplet activation properties and scavenged fraction of black carbon in liquid-phase clouds at the high-alpine research station Jungfraujoch (3580 m a.s.l.)

Abstract. Liquid clouds form by condensation of water vapour on aerosol particles in the atmosphere. Even black carbon (BC) particles, which are known to be slightly hygroscopic, have been shown to readily form cloud droplets once they have acquired water-soluble coatings by atmospheric aging processes. Accurately simulating the life cycle of BC in the atmosphere, which strongly depends on the wet removal following droplet activation, has recently been identified as a key element for accurate prediction of the climate forcing of BC. Here, to assess BC activation in detail, we performed in situ measurements during cloud events at the Jungfraujoch high-altitude station in Switzerland in summer 2010 and 2016. Cloud droplet residual and interstitial (unactivated) particles as well as the total aerosol were selectively sampled using different inlets, followed by their physical characterization using scanning mobility particle sizers (SMPSs), multi-angle absorption photometers (MAAPs) and a single-particle soot photometer (SP2). By calculating cloud droplet activated fractions with these measurements, we determined the roles of various parameters on the droplet activation of BC. The half-rise threshold diameter for droplet activation (Dhalfcloud), i.e. the size above which aerosol particles formed cloud droplets, was inferred from the aerosol size distributions measured behind the different inlets. The effective peak supersaturation (SSpeak) of a cloud was derived from Dhalfcloud by comparing it to the supersaturation dependence of the threshold diameter for cloud condensation nuclei (CCN) activation measured by a CCN counter (CCNC). In this way, we showed that the mass-based scavenged fraction of BC strongly correlates with that of the entire aerosol population because SSpeak modulates the critical size for activation of either particle type. A total of 50 % of the BC-containing particles with a BC mass equivalent core diameter of 90 nm was activated in clouds with SSpeak≈0.21 %, increasing up to ∼80 % activated fraction at SSpeak≈0.50 %. On a single-particle basis, BC activation at a certain SSpeak is controlled by the BC core size and internally mixed coating, which increases overall particle size and hygroscopicity. However, the resulting effect on the population averaged and on the size-integrated BC scavenged fraction by mass is small for two reasons: first, acquisition of coatings only matters for small cores in clouds with low SSpeak; and, second, variations in BC core size distribution and mean coating thickness are limited in the lower free troposphere in summer. Finally, we tested the ability of a simplified theoretical model, which combines the κ-Köhler theory with the Zdanovskii–Stokes–Robinson (ZSR) mixing rule under the assumptions of spherical core–shell particle geometry and surface tension of pure water, to predict the droplet activation behaviour of BC-containing particles in real clouds. Predictions of BC activation constrained with SSpeak and measured BC-containing particle size and mixing state were compared with direct cloud observations. These predictions achieved closure with the measurements for the particle size ranges accessible to our instrumentation, that is, BC core diameters and total particle diameters of approximately 50 and 180 nm, respectively. This clearly indicates that such simplified theoretical models provide a sufficient description of BC activation in clouds, as previously shown for activation occurring in fog at lower supersaturation and also shown in laboratory experiments under controlled conditions. This further justifies application of such simplified theoretical approaches in regional and global simulations of BC activation in clouds, which include aerosol modules that explicitly simulate BC-containing particle size and mixing state.

Preparation and characterisation of water soluble polyester coatings based on waste materials

PurposeThe purpose of this paper is to prepare cheap and environmentally friendly water soluble polyester coatings through the glycolysis of poly(ethylene terephthalate) (PET) waste.Design/methodology/approachA secondary value-added polyester coatings were prepared from PET waste. The first step was the de-polymerisation of PET waste by 2,2-dimethyl-1,3-propanediol with different molar ratios in the presence of different concentrations of zinc acetate as trans-esterification catalyst. The de-polymerised product was characterised by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1HNMR), differential scanning calorimetry and hydroxyl values. The polyesters were successfully synthesised by esterification of the glycolysed product with adipic acid, isophthalic acid, 2,2-dimethyl-1,3-propanediol and trimellitic anhydride in different ratios. FTIR and 1HNMR were used qualitatively and quantitatively to elucidate the structure of the prepared polyesters. Hydroxyl value and the physical properties of the prepared polyesters were also investigated. Two different curing agents were used to prepare the coatings based on the prepared polyesters.FindingsUseful coating products were obtained by chemical (glycolysis) of post consumed PET wastes. The 2,2-dimethyl-1,3-propanediol was found to be good glycol in the glycolysis of PET. It was noticed that the rate of glycolysis increases with increasing the amount of catalyst, time of glycolysis and amount of 2,2-dimethyl-1,3-propanediol. N,N-Dimethylethanol amine was a good neutralising agent used for the preparation of water soluble coatings based on glycolysed product of PET.Practical implicationsThe use of waste products like PET waste in water soluble coating systems will bring down the costs of the coatings and will also open a new market of recycled plastic materials and, hence, may provide a potential solution to the problems of solid waste management. It is an attractive option for environmentally friendly and efficient disposal of plastic waste.Originality/valueThe paper provides a potential way to use undesirable PET waste as industrial raw material. The coatings prepared are eco-friendly, soluble in water that can replace other expensive polyester coatings that are soluble in organic solvents and not environmentally coatings.

Shifts in soil bacterial communities induced by the controlled-release fertilizer coatings

Coated controlled-release fertilizers (CRFs) have been widely applied in agriculture due to their increased efficiency. However, the widespread and a lot of coated CRFs application may leave undesired coating residues in the soil due to their slow degradation. Limited information is available on the effects of substantial residual coatings on the soil bacterial community. By adding 0, 5, 10, 20, and 50 times quantities of residual coating from conventional application amount of resin and water-soluble coated CRFs, we studied the responses of soil properties and bacterial community composition to these two residual coatings in black soil. The results showed that the resin and water-soluble coatings did not essentially alter the properties of black soil or cause dramatic changes to bacterial diversity within the test concentration range. The residual resin and water-soluble coatings also did not distinctly alter the relative abundance of the top ten bacteria at phylum level. Heatmap results suggested that the treatments were basically clustered into two groups by concentration rather than types of coating material. Pearson correlation analysis showed that the Simpson's diversity index of the bacterial community was significantly correlated with microbial biomass carbon (MBC, r=0.394, P<0.05), and the richness index abundance-based coverage estimator (ACE) of the bacterial community was significantly correlated with microbial biomass nitrogen (MBN, r=0.407, P<0.05). Overall, results of this study suggested that substantial residual resin and water-soluble coatings with 0–50 times quantities of residual coating from conventional application amount of coated CRFs did not generate obviously negative impacts on the bacterial community in black soil.

COHERENT VORTEX STRUCTURES INSIDE THE CROSS-STREAMLINED OVAL DIMPLE

Results of experimental researches of the vortex structure inside the cross-streamlined oval dimple on a hydraulically smooth flat surface are presented. By means of flow visualization by the contrasting dyes and water soluble coatings the features of forming and evolution of coherent large-scale and small-scale vortex structures are determined inside the dimple. For small Reynolds numbers responding by laminar flow coherent vortices are not generated inside the oval dimple. For the Reynolds numbers about 10000 the cellular quasistable large-scale vortex structures are formed inside the dimple, which are ejected into the boundary layer above an aft dimple wall. For the developed turbulent flow a spindle vortex structure is generated in the dimple which is pressed to the front bottom part of the dimple.

Influence of water soluble coatings on posharvest quality of sweet cherry (Prunes avium L.) grown in Gilgit-Baltistan

The effects of semperfresh along with polyethylene bags on quality of cherries were studied. Freshly harvested cherry fruits (Prunes avium) were segregated into four groups and coated with three different levels of semperfresh i.e. 1, 2, and 3%, while the forth one left as a control. Half of the cherries from each of the above groups were sealed in low density perforated polyethylene bags while the other half of the cherries were placed in open wooden trays. Each group was analyzed for the different quality parameters like, firmness, weight loss, titratable acidity, total soluble solid, total sugar, ascorbic acid, pH, antioxidant activity, total phenolics compound and sensory evaluation. It was revealed from the study that the semperfresh was found effective to reduced weight loss, improved firmness appreciable ascorbic acid content and titratable acidity, high antioxidant activity and total phenolics compound and acceptable flavor, taste and color scores in fruits during storage time. The results of this study suggest that semperfresh 3% increased the shelf life of cherries up to 15 days at room temperature without any change in quality.

Adhesion of food-borne bacteria to stainless steel is reduced by food conditioning films

Preconditioning of stainless steel with aqueous cod muscle extract significantly impedes subsequent bacterial adhesion most likely due to repelling effects of fish tropomyosin. The purpose of this study was to determine if other food conditioning films decrease or enhance bacterial adhesion to stainless steel. Attachment of Pseudomonas fluorescens AH2 to stainless steel coated with water-soluble coatings of animal origin was significantly reduced as compared with noncoated stainless steel or stainless steel coated with laboratory substrate or extracts of plant origin. Coating with animal extracts also decreases adhesion of other food-relevant bacteria. The manipulation of adhesion was not attributable to growth inhibitory effects. Chemical analysis revealed that the stainless steels were covered by homogenous layers of adsorbed proteins. The presence of tropomyocin was indicated by appearance of proteins with similar molecular weight based in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, in several extracts that reduced adhesion but also extracts not containing this protein reduced bacterial adhesion, indicating that several molecular species may be involved in the phenomenon. It is a common perception that food materials facilitate bacterial adhesion to surfaces; however, this study demonstrates that aqueous coatings of food origin may actually reduce bacterial adhesion. Compounds from food extracts may potentially be used as nontoxic coatings to reduce bacterial attachment to inert surfaces.

Helium pycnometry as a tool for assessment of sealing efficiency in microencapsulation

There is a need for a fast and reliable method to evaluate the development in coating quality during coating, especially for fast dissolving coatings. In the present study, pycnometric density was evaluated as a tool for assessment of coating quality in terms of sealing efficiency for microspheres coated with polymeric aqueous solutions. Further, it was investigated if the method could be used to study effects of spray variables on the sealing efficiency of coated microspheres. The microcrystalline cellulose particles Ethispheres ®250 were coated with aqueous solutions of Hypromellose 5 and Povidone K-90F by Wurster bottom-spray technique. End products and samples drawn during coating were analysed in terms of pycnometric helium density and scanning electron microscopy (SEM). Experiments constituted a 2 3 factorial design with the following spray related variables: atomisation air flow, polymer type, and solution concentration/viscosity. Helium pycnometric density was seen to lower gradually during coating in all experiments and to follow a common pattern. The quantitative lowering in density was further seen to correlate to sealing of voids by gradual covering of the microsphere surface and thus the sealing efficiency. Hence, the present data suggests helium pycnometry as a tool for assessment of coating quality in terms of sealing efficiency. This goes particularly for testing of products coated with water-soluble coatings, where dissolution testing obviously is compromised. The specific data on sealing efficiency might also add to other analytical methods in the analysis of coating quality, in general. End point densities of coated microspheres were seen to reveal differences in sealing efficiency between polymers. Measured densities of final products were also generally seen to reflect differences in coating permeability caused by variations in spray conditions. Thus, the measurement of density is a potential a tool for evaluation of spray conditions with respect to sealing of microspheres and identification of critical spray conditions.

Structure, properties and application to water-soluble coatings of complex antimicrobial agent Ag-carboxymethyl chitosan-thiabendazole

The structure, properties and application to water-soluble coatings of a new complex antimicrobial agent Ag-carboxylmethyl citosan-thiabendazole (Ag-CMCTS-TBZ) prepared from different materiel ratios were reported. The silver ions were preferably coordinated with the free — NH2 groups and the — OH groups of secondary alcohol and carboxyl in CMCTS. TBZ preferably bonded to carboxyl group in CMCTS by electrostatic force and hydrogen bonding. Increase in silver ions content in the complex agent improved to some limited extent the antibacterial activity, but enhanced coloring and cost of the complex agent. Increase in TBZ content resulted in increase of antifungal activity, but decrease of water solubility of the complex agent. The antimicrobial MICs of the complex agent to Esherichia coli, Staphylococcus aureus, Candida albicans, Aspergillus niger, Mucor sp. were 20 – 80, 15 – 60, 20 – 55, 40 – 250, and 400 – 1700 mg/kg, respectively. Addition of 0.1% of this complex agent to acrylic emulsion paint made the paint without substantial change in color, luster, viscosity, odor or pH value, but with an excellent and chronically persisting broad-spectra antimicrobial activity.

The effect of temperature development during stone impact on damage morphology and adhesion of organic coatings

The influence of the heat generation induced by stone impact events is shown to be significant for the damage process of organic coatings. Experimental results on different water-soluble coatings are presented, indicating a rise in surface temperature of more than 80°C during single impacts with kinetic energies of more than 0.01 J. This temperature dissipates within a few tens of milliseconds. The damage morphology is determined by brittle fracture processes and plastic deformation effects in the case of low and high impact induced temperatures, respectively.

Surface modification of intraocular lenses to reduce corneal endothelial damage

Two methods of surface modification of PMMA, permanent and temporary, were investigated for use on intraocular lenses to reduce corneal endothelial damage due to corneal-IOL touch. Monomer grafting using gamma irradiation was found to produce permanently hydrophilic surfaces. Temporary surface modifications developed and tested were peelable and dissolvable coatings. Test samples were touched to freshly excised rabbit corneas to evaluate the effectiveness of the various surface modifications in reducing endothelial cell damage. This touch testing was performed using static testing in which the test sample was touched to the cornea without movement and dynamic testing in which there was relative movement between the cornea and the test sample. While unmodified PMMA did significant cell damage in both static and dynamic tests perpamently modified (hydrophilic grafted) surfaces were found to perform well in the static, but not in the dynamic tests. Dissolvable coatings performed well in both tests, even with very thin coatings. There was little differentiation between the various water-soluble coatings tested. Due to its characteristics and rate of dissolution, polyvinyl alcohol appears to be an optimum material for coating IOLs. A series of in vitro and in vivo tests performed to assess its safety indicate that PVA is nontoxic and safe in animal eyes.

Viscosity variation and solvent balance in water-soluble coatings

Viscosity variation and solvent balance in water-soluble coatings