Macroporous Silicone Sheets Integrated with Meshes for Various Applications

2019 ◽  
Author(s):  
Gen Hayase ◽  
Shin-ichiro M. Nomura
Keyword(s):  
Acetic Acid ◽  
Hydrophobic Surface ◽  
Ammonia Solution ◽  
Water Droplets ◽  
Composite Sheet ◽  
Oil Separation ◽  
Giant Vesicle ◽  
Silicone Gels

Flexible macroporous silicone gels were prepared using methyltrimethoxysilane and dimethyldimethoxysilane as co-precursors via a two-step reaction catalyzed by acetic acid and ammonia solution. A sheet-shaped material was integrated with the gel by immersing the mesh in the sol during the reaction. The mesh reinforced sheet having a thickness of several millimeters was resistant to bending and pulling and easy to handle. The composite sheet was used for various applications such as water-oil separation, manipulation of water droplets by adsorption on the hydrophobic surface, and preparation of giant vesicle dispersion.

Macroporous Silicone Sheets Integrated with Meshes for Various Applications

2019 ◽  
Author(s):  
Gen Hayase ◽  
Shin-ichiro M. Nomura
Keyword(s):  
Acetic Acid ◽  
Hydrophobic Surface ◽  
Ammonia Solution ◽  
Water Droplets ◽  
Composite Sheet ◽  
Oil Separation ◽  
Giant Vesicle ◽  
Silicone Gels

Flexible macroporous silicone gels were prepared using methyltrimethoxysilane and dimethyldimethoxysilane as co-precursors via a two-step reaction catalyzed by acetic acid and ammonia solution. A sheet-shaped material was integrated with the gel by immersing the mesh in the sol during the reaction. The mesh reinforced sheet having a thickness of several millimeters was resistant to bending and pulling and easy to handle. The composite sheet was used for various applications such as water-oil separation, manipulation of water droplets by adsorption on the hydrophobic surface, and preparation of giant vesicle dispersion.

scholarly journals Heterogeneous freezing of water droplets containing kaolinite particles

2011 ◽  
Vol 11 (9) ◽  
pp. 4191-4207 ◽  
Author(s):  
B. J. Murray ◽  
S. L. Broadley ◽  
T. W. Wilson ◽  
J. D. Atkinson ◽  
R. H. Wills
Keyword(s):  
Cooling Rate ◽  
Surface Area ◽  
Clay Mineral ◽  
Constant Temperature ◽  
Hydrophobic Surface ◽  
Supercooled Liquid ◽  
Stochastic Approach ◽  
Solid Particles ◽  
Rate Coefficients ◽  
Water Droplets

Abstract. Clouds composed of both ice particles and supercooled liquid water droplets exist at temperatures above ~236 K. These mixed phase clouds, which strongly impact climate, are very sensitive to the presence of solid particles that can catalyse freezing. In this paper we describe experiments to determine the conditions at which the clay mineral kaolinite nucleates ice when immersed within water droplets. These are the first immersion mode experiments in which the ice nucleating ability of kaolinite has been determined as a function of clay surface area, cooling rate and also at constant temperatures. Water droplets containing a known amount of clay mineral were supported on a hydrophobic surface and cooled at rates of between 0.8 and 10 K min−1 or held at constant sub-zero temperatures. The time and temperature at which individual 10–50 μm diameter droplets froze were determined by optical microscopy. For a cooling rate of 10 K min−1, the median nucleation temperature of 10–40 μm diameter droplets increased from close to the homogeneous nucleation limit (236 K) to 240.8 ± 0.6 K as the concentration of kaolinite in the droplets was increased from 0.005 wt% to 1 wt%. This data shows that the probability of freezing scales with surface area of the kaolinite inclusions. We also show that at a constant temperature the number of liquid droplets decreases exponentially as they freeze over time. The constant cooling rate experiments are consistent with the stochastic, singular and modified singular descriptions of heterogeneous nucleation; however, freezing during cooling and at constant temperature can be reconciled best with the stochastic approach. We report temperature dependent nucleation rate coefficients (nucleation events per unit time per unit area) for kaolinite and present a general parameterisation for immersion nucleation which may be suitable for cloud modelling once nucleation by other important ice nucleating species is quantified in the future.

scholarly journals Dust removal from a hydrophobic surface by rolling fizzy water droplets

RSC Advances ◽  
2020 ◽  
Vol 10 (34) ◽  
pp. 19811-19821 ◽  
Author(s):  
Bekir Sami Yilbas ◽  
Ghassan Hassan ◽  
Hussain Al-Qahtani ◽  
Saeed Bahatab ◽  
Ahmet Z. Sahin ◽  
...  
Keyword(s):  
Removal Rate ◽  
Hydrophobic Surface ◽  
Dust Removal ◽  
Liquid Droplets ◽  
Water Droplets

Here, environmental dust cleaning from an inclined hydrophobic surface by rolling liquid droplets has been studied and the influence of fluid droplets on the dust removal rate has been examined.

The Collision Behavior of Droplets Splitted from a Droplet that Rebounded on Super-Hydrophobic Surface

2015 ◽  
Vol 723 ◽  
pp. 968-971 ◽  
Author(s):  
Zheng Yong Huang ◽  
Jian Li ◽  
Fei Peng Wang ◽  
Huan Huan Xia ◽  
Mao Chang Li
Keyword(s):  
Contact Time ◽  
Hydrophobic Surface ◽  
Reynolds Numbers ◽  
Elastic Collision ◽  
Water Droplets ◽  
Water Contact ◽  
Ice Accumulation ◽  
Pollution Flashover ◽  
Water Accumulation ◽  
Spreading Time

Droplet rebounding on super-hydrophobic surfaces is critical to suppress pollution flashover (i.e. enhancement of pollution flashover-voltage) and to reduce ice accumulation on insulators. This paper presents a novel way to reduce water accumulation on surface via the elastic collision between droplets splitted from a droplet that has rebounded from super-hydrophobic surface. The water-mass that contacted with surface will be reduced resultantly. The influence of hydrophobicity of the surface on contact time and spreading time of water droplets are discussed. The collision behavior between the splitted droplets is indicated by the surface charge that was induced by the rebounding droplets on super-hydrophobic surface. Experimental results show that the super-hydrophobic surface endows water droplets with shorter contact time, spreading time than those values obtained on a bare glass. Specific Web and Reynolds numbers can lead to the elastic rebounding between water droplets, delaying the water contact with the super-hydrophobic surface. The contact electrification between the rebounded droplet and the super-hydrophobic surface renders the droplet charged, thus determines the collision behavior of the splitted droplets that born from the rebounded droplet.

scholarly journals Catalytic Performance of SBA-15-Supported Poly (Styrenesulfonic Acid) in the Esterification of Acetic Acid with n-Heptanol

2020 ◽  
Vol 10 (17) ◽  
pp. 5835
Author(s):  
Abdulaziz Ali Alghamdi ◽  
Yahya Musawi Mrair ◽  
Fahad A. Alharthi ◽  
Abdel-Basit Al-Odayni
Keyword(s):  
Acetic Acid ◽  
Sulfonic Acid ◽  
Active Sites ◽  
Structural Characteristics ◽  
High Surface ◽  
High Surface Area ◽  
Reaction Times ◽  
Hydrophobic Surface ◽  
Catalytic Performance ◽  
Catalyst Load

A polystyrene sulfonic acid-functionalized mesoporous silica (SBA-15-PSSA) catalyst was synthesized via an established multistep route, employing 2-bromo-2-methylpropionyl bromide as initiator of atom transfer radical polymerization. Fourier-transform infrared spectroscopy, thermogravimetric/differential thermal, Brunauer–Emmett–Teller, and transmission electron microscopy analyses revealed outstanding structural characteristics of the catalyst, including highly ordered mesopores, high surface area (726 m2/g), and adequate estimated concentrations of active sites (0.70 mmol H+/g). SBA-15-PSSA’s catalytic performance was evaluated in the esterification of acetic acid and n-heptanol as a model system at various temperatures (50–110 °C), catalyst loads (0.1–0.3 g), and reaction times (0–160 min). The conversion percentage of acetic acid was found to increase with the temperature, catalyst load, and reaction time. Furthermore, results indicated a fast conversion in the first 20 min of the reaction, with remarkable conversion values at 110 °C, reaching 86%, 94%, and 97% when the catalyst load was 0.1, 0.2, and 0.3 g, respectively; notably, at this temperature, 100% conversation was achieved after 60 min. At 110 °C, the reaction conducted in the presence of 0.3 g of catalyst displayed more than 6.4 times the efficiency of the uncatalyzed reaction. Such activity is explained by the concomitant presence in the polymer of strong sulfonic acid moieties and a relatively high hydrophobic surface, with adequate numbers of active sites for ester production.

Study on Discharge of Separated Water Droplets in DC Field

2011 ◽  
Vol 130-134 ◽  
pp. 3276-3279
Author(s):  
Zong Xi Zhang ◽  
Shan Feng Yin
Keyword(s):  
Electric Field ◽  
Hydrophobic Surface ◽  
Electrical Equipment ◽  
Water Droplets ◽  
Surface Flashover ◽  
Voltage Drops ◽  
Flashover Voltage ◽  
Dc Electric Field ◽  
Water Drops ◽  
And Migration

With the accelerating construction of strong smart grid, and the grid voltage level rising, performance requirements for the electrical insulation of electrical equipment also continue to increase. In terms of the advantages of RTV on antifouling, RTV-based paints coated insulator coating capacity of its flash tolerance can significantly increase, mainly due to RTV coating hydrophobic hydrophobicity and migration. But when the hydrophobic surface is in the fully wet, many small drops of water in the surface will be gathered into big drops of water, and these large droplets will distort the surface electric field of the medium. So the flashover voltage of the hydrophobic surface’s separated water droplets under DC electric field are analyzed comparatively in this paper, while some influencing factors such as different medias and volume of water drops, are introduced in specific experiments, and their effects on the flashover voltage are analyzed; under DC electric field experiment on the surface of hydrophobic and hydrophilic surface flashover voltage drops separation characteristics were studied.

scholarly journals Facile construction of a polydopamine-based hydrophobic surface for protection of metals against corrosion

RSC Advances ◽  
2017 ◽  
Vol 7 (19) ◽  
pp. 11528-11536 ◽  
Author(s):  
Nan Wei ◽  
Yueyue Jiang ◽  
Ye Ying ◽  
Xiaoyu Guo ◽  
Yiping Wu ◽  
...  
Keyword(s):  
Metal Surfaces ◽  
Hydrophobic Surface ◽  
Water Droplets ◽  
Protection Of Metals

Metal surfaces with a hydrophobic feature, which could prevent percolation of water droplets and improve their capability against corrosion, arouse extensively interest.

scholarly journals Formation of double emulsion micro-droplets in a microfluidic device using a partially hydrophilic–hydrophobic surface

RSC Advances ◽  
2021 ◽  
Vol 11 (56) ◽  
pp. 35653-35662
Author(s):  
Ampol Kamnerdsook ◽  
Ekachai Juntasaro ◽  
Numfon Khemthongcharoen ◽  
Mayuree Chanasakulniyom ◽  
Witsaroot Sripumkhai ◽  
...  
Keyword(s):  
Flow Rate ◽  
Frequency Ratio ◽  
Encapsulation Efficiency ◽  
Double Emulsion ◽  
Hydrophobic Surface ◽  
Water Droplets ◽  
Oil In Water ◽  
Rate Ratios ◽  
Frequency Ratios ◽  
Ratio Range

(a) Droplet encapsulation efficiency & inner and outer diameters of water-in-oil-in-water droplets at various frequency ratios and flow rate ratios and (b) Images of water-in-oil-in-water droplets over a frequency-ratio range of fr = 0.73–1.30

scholarly journals Coalescence of Binary Droplets in the Transformer Oil Based on Small Amounts of Polymer: Effects of Initial Droplet Diameter and Collision Parameter

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2054
Author(s):  
Yiting Wang ◽  
Lijuan Qian ◽  
Zhongli Chen ◽  
Fang Zhou
Keyword(s):  
Kinetic Energy ◽  
Droplet Diameter ◽  
Transformer Oil ◽  
Water Droplets ◽  
Droplet Deformation ◽  
Oil Separation ◽  
Coalescence Time ◽  
Maximum Deformation ◽  
Initial Droplet ◽  
Central Collisions

In engineering applications, the coalescence of droplets in the oil phase dominates the efficiency of water-oil separation. To improve the efficiency of water-oil separation, many studies have been devoted to exploring the process of water droplets colliding in the oil phase. In this paper, the volume of fluid (VOF) method is employed to simulate the coalescence of water droplets in the transformer oil based on small amounts of polymer. The influences of the initial diameter and collision parameter of two equal droplets on droplet deformation and coalescence time are investigated. The time evolution curves of the dimensionless maximum deformation diameter of the droplets indicate that the larger the droplet diameter, the more obvious the deformation from central collisions. As the collision parameter increases, the contact area of the two droplets, as well as the kinetic energy that is converted into surface energy, decreases, resulting in an increase in droplet deformation. Furthermore, the effects of the initial droplet diameter and collision parameter on coalescence time are also investigated and discussed. The results reveal that as the initial droplet diameter and collision parameter increase, the droplet coalescence time increases.

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