Modeling Water Movement in Heterogeneous Water-Repellent Soil: 1. Development of a Contact Angle-Dependent Water-Retention Model

2007 ◽  
Vol 6 (3) ◽  
pp. 436-445 ◽  
Author(s):  
J. Bachmann ◽  
M. Deurer ◽  
G. Arye
Keyword(s):  
Contact Angle ◽  
Water Retention ◽  
Water Movement ◽  
Water Repellent ◽  
Retention Model

Unsaturated soil water movement in hysteretic and water repellent field soils

1996 ◽  
Vol 184 (3-4) ◽  
pp. 153-173 ◽  
Author(s):  
J.C. van Dam ◽  
J.H.M. Wösten ◽  
A. Nemes
Keyword(s):  
Soil Water ◽  
Unsaturated Soil ◽  
Water Movement ◽  
Water Repellent ◽  
Field Soils ◽  
Soil Water Movement

scholarly journals Water Movement and Finger Flow Characterization in Homogeneous Water-Repellent Soils

2018 ◽  
Vol 17 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Yichen Wang ◽  
Xiaofang Wang ◽  
Henry Wai Chau ◽  
Bingcheng Si ◽  
Ning Yao ◽  
...  
Keyword(s):  
Water Movement ◽  
Water Repellent ◽  
Flow Characterization

Fast and simple fabrication of SiO2/poly(vinylidene fluoride) coated cotton fabrics with asymmetric wettability via a facile spray-coating route

2018 ◽  
Vol 89 (6) ◽  
pp. 1013-1026 ◽  
Author(s):  
Rongrong Yu ◽  
Mingwei Tian ◽  
Lijun Qu ◽  
Shifeng Zhu ◽  
Jianhua Ran ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Contact Angle ◽  
Water Contact Angle ◽  
Vinylidene Fluoride ◽  
Spray Coating ◽  
Cotton Fabrics ◽  
Water Repellent ◽  
Water Contact ◽  
Repellent Property ◽  
Poly Vinylidene Fluoride

Cotton fabrics with hydrophilic-to-hydrophobic asymmetric surfaces are attractive as potential utilizable structures for functional garments. The spray-coating route could be deemed as a fast and simple way to achieve asymmetric surfaces. In this paper, SiO2 nanoparticles with size ∼ 205 nm were synthesized via the modified sol-gel method, and then modified with poly(vinylidene fluoride) (PVDF) to form a hydrophobic surface. The SiO2 nanoparticles modified with PVDF were uniformly deposited on the outer surface of cotton fabric aided with the robust air flow force from the sprayer. The morphology and chemical structures were characterized by scanning electron microscopy, mapping, atomic force microscopy, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. The results indicated that SiO2 nanoparticles were evenly deposited on the surface of cotton fibers and stable interfacial interaction occurred between SiO2 and PVDF molecular chains. The existence of SiO2 could increase the roughness of the fabric surface, which could enhance the water-repellent property of the coated fabrics. Furthermore, the water-repellent property and thermal insulation properties were evaluated via the water contact angle and thermal conductivity tests, respectively, and the results showed that 20 wt.% SiO2/PVDF fabric achieved a desirable level of contact angle, 136.6°, which was the largest water contact angle among all the samples, and the lowest thermal conductivity of 0.033 W/mK, resulting from the existence of SiO2 nanoparticles. Such a fast and simple spray-coating strategy could be widely introduced into asymmetric fabric modification, and such asymmetric fabrics with reasonable water-repellent and thermal insulating outer surfaces could act as candidates in the field of functional garments.

Curing Time and Water Repellent Properties of Dammar-Titanium Dioxide Thin Film

2015 ◽  
Vol 1112 ◽  
pp. 359-362
Author(s):  
Aisyah Nor Hasnan ◽  
Azizah Hanom Ahmad
Keyword(s):  
Contact Angle ◽  
Titanium Dioxide ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Water Repellent ◽  
Coating System ◽  
Curing Time ◽  
Coating Surface ◽  
Natural Resin ◽  
Before And After

Dammar plant resin is a local natural resin that can be bled from Dipterocaupacea sp of tree. It can be found abundantly in Malaysia’s tropical forest especially in Sarawak. Dammar and Titanium Dioxide was mixed in a various wt% to produce Dammar-modified Titanium Dioxide coating system. The modified coating systems were then spin-coated onto Aluminium Q-panel as the substrate. Coated Q-panels were left to cure at room temperature. The curing time was evaluated using dust free stage. The addition of Titanium Dioxide into the coating system fastens the curing time taken for the coated Q-panel to be cure. It only took about 11-12 minutes to dry compared to the coating system before the addition of Titanium Dioxide where a quite long duration required, 32 minutes. Contact angle measurement was also carried out in order to determine the wettability of the coating system. The surface coated with dammar-modified titanium dioxide found to be hydrophobic where a quite large contact angle obtained for the sample with 3 wt% of Titanium Dioxide (PDT3). The water droplets actually rest on the coating surface without wetting the surface. Water absorption test was done to strengthen the contact angle results where coated substrate was soaked into distilled water for 24 hours and being weighed before and after soaking. The difference of before and after soaking weigh showed that the coating surface does not absorb that much water where only approximately 0.02% of water being absorbed by the coating system for 3 wt%. It proved that the coating systems applied are hydrophobic.

scholarly journals Transmittance Control of a Water-Repellent-Coated Layer on a Tensioned Web in a Roll-to-Roll Slot-Die Coating System

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 4003
Author(s):  
Seongyong Kim ◽  
Minho Jo ◽  
Jongsu Lee ◽  
Changwoo Lee
Keyword(s):  
Contact Angle ◽  
Solar Cells ◽  
Control Method ◽  
Dominant Factor ◽  
Water Repellent ◽  
Process Conditions ◽  
Slot Die Coating ◽  
Roll To Roll ◽  
Slot Die ◽  
Transparent Water

Solar cells are important alternatives to fossil fuels for energy generation in today’s world, where the demand for alternative, renewable sources of energy is increasing. However, solar cells, which are installed outdoors, are susceptible to pollution by environmental factors. A solution to overcome this limitation involves coating solar cell surfaces with functional coatings. In this study, we propose a transmittance control method for a tensioned web in a roll-to-roll, transparent, water-repellent film coating. First, we analyzed the effects of process conditions on the transmittance and contact angle of the transparent water-repellent film during roll-to-roll slot-die coating. It was confirmed that the tension was the most dominant factor, followed by the coating gap. Through the tension control, the transmittance was changed by 3.27%, and the contact angle of the DI water was changed by 17.7°. In addition, it was confirmed that the transmittance was changed by 0.8% and the contact angle of DI water by 3.9° via the coating gap control. Based on these results, a transmittance prediction model was developed according to the tension and coating gap, and was then verified experimentally. Finally, a water-repellent film with a high transmittance of 89.77% was obtained using this model.

Preparation and Water Resistance of the New Water Epellent Agent of Paper Lunch Boxes

2011 ◽  
Vol 236-238 ◽  
pp. 1199-1202
Author(s):  
Shu Fang Zhou ◽  
Chuan Shan Zhao ◽  
Jing Jing Wang
Keyword(s):  
Contact Angle ◽  
Water Resistance ◽  
Dry Weight ◽  
Water Repellent ◽  
Optimal Conditions ◽  
Mass Ratio ◽  
Domestic Water ◽  
Oil Resistance ◽  
Effect Of Water

In this paper, a kind of sizing synergist,AKD,cationic rosin(CRS) and oil resistance agent were mixed in different proportions, we make it as a kind of new water repellent agent ,and for internal sizing. The best dosage and the composite ratio of the synergist, AKD, cationic rosin and oil resistance agent was discussed mainly in this experiment. And then the copy paper were tested of the substanceweight and contact angle, and compared with the water resistance when the domestic water repellent agent or AKD was added alone. Conclusions of this experiment are following: the optimal conditions were that the mass ratio of AKD and CRS is 6:4, the additive level of AKD and the cationic rosin is 6% (based on dry weight of pulp), the quantity of the sizing synergist is 0.5% , and no oil resistance agent was added, the effect of water resistance is best.

scholarly journals A new and simple water retention model for root-permeated soils

2016 ◽  
Vol 6 (1) ◽  
pp. 106-111 ◽  
Author(s):  
C. W. W. Ng ◽  
J. J. Ni ◽  
A. K. Leung ◽  
Z. J. Wang
Keyword(s):  
Water Retention ◽  
Retention Model

Influence of TiO2 on Selfclean Bio Coating

2013 ◽  
Vol 315 ◽  
pp. 399-403 ◽  
Author(s):  
Nurulsaidatulsyida Sulong ◽  
Anika Zafiah Mohd Rus
Keyword(s):  
Contact Angle ◽  
Organic Contaminants ◽  
Concrete Surface ◽  
Waste Cooking Oil ◽  
Water Repellent ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
The Difference ◽  
Micro Features ◽  
Coated Surfaces

Treatment on the exposed surface to the environmental attack was studied based on biopolymer coating from waste cooking oil doped with a superhydrophilic filler of Titanium Dioxide (TiO2), known as TOP. TOP was found to affect the physical properties of the coated concrete surface in a systematic way. Contact angle measurements are interpreted with respect to nanoand micro-features existing on the surface of the water repellent superhydrophilic filler filled bio-polymer composite coating. The smooth coated surfaces of polymer filled or doped with superhydrophobic filler shows the systematic increasing static Waste Contact Angle, WCA (θst) and revealed that polymer filled superhydrophobic fillers by only 2.0 % shows the ability to form superhydrophobicity property. Scanning Electron Microscope (SEM) pictures revealed the difference between the concrete surface roughness of concrete biopolymer with and without TOP coating is to provide self-cleaning concrete biopolymer coating based on two principal ways: (1) the development of surface coating of semiconducting photocatalytic superhydrophilic. (2) If such a superhydrophilic is illuminated by light, then grease, dirt and organic contaminants will be decomposed and can easily be swept away by rain.

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