Water Repellency Test Research Articles

Hydrophobic Aerogels from Vinyl Polymers Derived from Radical Polymerization: Proof-of-Concept.

Hydrophilicity is one important drawback of bio-based aerogels. To overcome this issue, a novel approach for the preparation of mesoporous, water repellent aerogels is introduced, which combines synthesis of cross-linked bio-based copolymers from methacrylate copolymerizations, followed by solvent exchange and supercritical drying steps. The influence of monomers with different nonpolar ester groups (methyl, vanillin, tetrahydrofurfuryl) on textural properties and water contact angles of the dry products is assessed. Final aerogels show generally high overall porosities (≈96%), low densities (0.07-0.11gcm-3) as well as fine, mainly mesoporous networks, and specific surface areas in the range of 120-240m2g-1. Hereby, choice of the methacrylate ester groups results in differences of the resulting pore-size distributions. Water repellency tests show stable static water contact angles in the hydrophobic range (≈100°) achieved for the substrate containing the vanillin ester group. On the contrary the other substrates absorb water quickly, which indicates a decisive role of the ester group. The presented approach opens up a new pathway to bio-based aerogels with intrinsic hydrophobicity. It is suggested that the properties are tailored by the choice of the monomer structure, hence enabling further adaption and optimization of the products.

Super-Hydrophobicity of Polyester Fabrics Driven by Functional Sustainable Fluorine-Free Silane-Based Coatings.

Polyester fibers are widely employed in a multitude of sectors and applications from the technical textiles to everyday life thanks to their durability, strength, and flexibility. Despite these advantages, polyester lacks in dyeability, adhesion of coating, hydrophilicity, and it is characterized by a low wettability respect to natural fibers. On this regard, beyond the harmful hydrophobic textile finishings of polyester fabrics containing fluorine-compounds, and in order to avoid pre-treatments, such as laser irradiation to improve their surface properties, research is moving towards the development of fluorine-free and safer coatings. In this work, the (3-glycidyloxypropyl)trimethoxysilane (GPTMS) and various long alkyl-chain alkoxysilanes were employed for the fabrication in the presence of a catalyst of a water-based superhydrophobic finishing for polyester fabrics with a simple sol-gel, non-fluorinated, sustainable approach and the dip-pad-dry-cure method. The finished polyester fabrics surface properties were investigated by static and dynamic water repellency tests. Additionally, the resistance to common water-based liquids, abrasion resistance, moisture adsorption, and air permeability measurements were performed. Scanning electron microscopy was employed to examine the micro- and nano-morphology of the functionalized polyester fabrics surfaces. The obtained superhydrophobic finishings displayed high water-based stain resistance as well as good hydrophobicity after different cycles of abrasion.

Effect of hydrocarbonic pollutants on the stability and soil water repellency intensity: A case study in Bandar Abbas Oil Refinery, Hormozgan province, Iran

Background: The contamination of soil and water with hydrocarbonic pollutants is a major environmental problem. Soil water repellency will interrupt water infiltration, and may decline plant growth and potentially trigger soil erosion. The aim of this study was to investigate the effect of soil and water contamination by oil on soil water repellency, where the soil has been oil-contaminated due to mismanagement of the lands surrounding the refineries, and many of the trees in the area have dried up. Methods: Water drop penetration time test (WDPT) was performed on contaminated soils. To investigate the effect of the surface water contamination on soil, handmade soil samples were collected and successive dry/wet cycles were applied to them by contaminated and non-contaminated waters. Subsequently, soil water repellency tests, including molarity of ethanol droplet (MED), water and ethanol sorptivity were performed on soil samples. The soils were passed through a 2 mm sieve after being air-dried and the soil texture was determined by pipette method. The SWR was measured by WDPT in the area contaminated with petroleum compounds and 7 to 10 replicates were assigned to each location. In order to determine the effect of water contamination on the area soil and to measure water repellency in the laboratory, disturbed soil samples (36 samples) with a bulk density equal to 80% of the reference bulk density were prepared. Results: The results showed that soil oil-contamination causes water repellency, increased WDPT, a significant increase in water repellency index, and a significant decrease in cosθ at the level of 0.001. The effect of water contamination on the indices and cosθ were statistically significant at the 0.001 and 1% levels, respectively. Therefore, contaminated water increased the water repellency of the soil after successive dry/wet cycles. Conclusion: Significant positive correlations between organic and water repellency indices and significant negative correlations between cosθ and organic indices indicate the effect of oil-contamination of water and soil on creating and increasing the intensity of soil water repellency.

Effect of Biochar Application on Physicochemical and Hydraulic Properties of Loess

Biochar is important for optimizing soil physical structure and improving soil water retention. The saturated water capacity test, water repellency test, and permeability coefficient test were used to study the effects of biochar additive amount (0, 2, 5, 10, 15, and 20 g/kg) and particle size (>2 mm, 2 mm–0.075 mm, and <0.075 mm) on the basic physicochemical and hydraulic properties of loess. The results showed that with the increase of biochar additive content, the relative particle density decreased linearly (R2 = 0.984); the plastic limit, liquid limit, and plasticity index increased (R2 = 0.947, 0.991, and 0.984, respectively); the maximum dry density decreased (R2 = 0.900); and the optimal water content and saturated water content increased gradually. At the same time, the soil’s pH increased (R2 = 0.957), the soil water repellency decreased, and the water infiltration became easier, but the soil’s permeability coefficient (saturated water conductivity) decreased. When the the biochar particles size is smaller, the soil’s water repellency and permeability coefficient reduced. Studies had shown that the application of biochar makes the loess infiltrate easily, seepage slowly, and contain more water, which improve the water infiltration characteristics and water retention capacity of loess.

Development of shrink resistance cotton using fluorocarbon

An attempt has been made to develop shrink resistance cotton textile by making it hydrophobic. The cotton fabric was made hydrophobic by treating with fluorocarbon resin emulsion at varying concentrations along with catalyst. The hydrophobicity was measured by carrying out water repellency test and also determining the water contact angle. The air permeability of cotton fabric was also determined and was not adversely affected. The untreated and treated cotton fabric was subjected to repeated domestic laundry condition and shrinkage was measured. In order to determine the impact of fluorocarbon treatment on fabric, the physical properties of treated and untreated cotton fabrics were compared. No adverse impact was observed in colour fastness properties. The tensile and tear strength showed good retention even at higher concentration of water repellent chemicals. This work finds wide use in home textiles and hotel industry. This work is of industrial interest as value added shrink resistance cotton textiles can fetch more export earnings.

Effect of modified ZnO nanoparticle on the properties of polylactide ultrafine fibers

ABSTRACTZinc oxide (ZnO) was modified with hexadecyltrimethoxysilane (HDTMS) to obtain hydrophobicity and used to reinforce polylactide (PLA), an environmentally friendly polymer. The PLA/HDTMS‐modified ZnO (m‐ZnO) nanocomposite prepared by adding m‐ZnO to the PLA matrix was fabricated into ultrafine fiber using electrospinning. Neat PLA and PLA/ZnO were used for comparisons. Structural analysis of the nanoparticles proved that the ZnO was modified successfully, and that the modification affected dispersibility and hydrophobicity, as observed by morphological, visual, and water repellency tests. The morphological analysis of the electrospun ultrafine fabrics under suitable conditions confirmed that the nanoparticles were well incorporated, and the desired functional changes were observed. Measurement of water repellency and mechanical, thermal properties were used to analyze the effect of nanoparticle modification and composition on fabrics. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47446.

Water repellency improvement of cellulosic textile fibers by betulin and a betulin-based copolymer

Betulin is a naturally abundant and hydrophobic compound in the outer bark of birch and can readily be obtained by solvent extraction. Here, solutions of betulin were used to treat cotton fabrics and improve their water repellency. Cotton fabric impregnated in a solution of betulin in ethanol showed a contact angle for water of approximately 153° and reached a water repellency score of 70 according to a standard water repellency test method. A betulin-terephthaloyl chloride (TPC) copolymer was synthesized. Both betulin and betulin-TPC copolymer were characterized by nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. The copolymer was characterized by size exclusion chromatography and differential scanning calorimetry. When impregnated with a solution of betulin-TPC copolymer in tetrahydrofuran, a cotton fabric showed a water contact angle of 151° and also reached a water repellency score of 70. Films based on betulin and betulin-TPC copolymer were prepared and coated onto the surface of the fabrics by compression molding. These coated fabrics showed water contact angles of 123° and 104° respectively and each reached a water repellency score of 80.

Development of multifunctional cotton using fluorocarbon resin

An attempt has been made to develop multifunctional cotton fabric, possessing water repellent, stain repellent, shrink resistance and quick dry properties using fluorocarbon resin. The hydrophobicity of cotton fabric was determined by carrying out water repellency test, taking scanning electron microscopic photographs and measuring water contact angle. The durability of hydrophobicity of cotton was tested till 20 washes and found satisfactory. Oil repellency was determined employing hydrocarbons resistance test. The air permeability of cotton fabric was also determined keeping in view the impact on breathability of treated cotton and was found quite good. The untreated and treated cotton fabric was subjected to repeated domestic laundry condition, and shrinkage was measured, which indicated excellent shrink resistance behaviour because of its water repelling characteristic. This hydrophobicity of cotton also added to its quick dry behaviour even at low temperature and high relative humidity. The physical properties of treated dyed cotton fabric samples were compared with untreated, and no significant changes were observed in colour fastness to washing, rubbing, perspiration and light. The tensile and tear strength showed good retention even at higher concentration of fluorocarbon resin. This work is of great industrial importance for textile products used in home textiles. The textile industry can fetch more export earnings by doing multiple value addition using the same chemical. The work reported in the literature is about using fluorocarbon and developing water- and oil-repellent fabrics. In the present work, apart from water and oil repellency, shrink resistance and quick dry behaviour of cotton textile has also been established using same fluorocarbon because of hydrophobicity imparted to cotton.

Fabrication of a silica aerogel and examination of its hydrophobic properties via contact angle and 3M water repellency tests

Aerogels are dry gels with a very high specific pore volume. Aerogels with increased hydrophobicity have significant potential to expand their use as lightweight materials. Considering its special nanostructure and exceptional properties, this paper focuses on the synthesis and hydrophobic evaluation of a silica aerogel. The structural properties were investigated by measuring density, SEM micrographs, and BET analyses. Also, the hydrophobic evaluation was carried out by measuring 3M water repellency and water/alcohol contact angle. The BET analysis showed successful synthesis of the nanoporous silica aerogel with a pore size of 24 nm and porosity of 89%. The synthesized aerogel showed 3M water repellency of 3 and water contact angle of 129.6°. Also, it is worth-mentioning that as the alcohol content of the drops in 3M water repellency test is increased, the drop contact angle is decreased due to its lower surface tension. Thus, the contact angle reaches the zero at 3M water repellency test number of 4 (water/alcohol 60/40).

Water Repellency of Monument Soil Treated by Tung Oil

Earthen monuments exposed at archeological sites are afflicted by a series of diseases, such as shrinkage, cracking, and collapse, related to moisture evaporation or partially soaked in ground water. Water repellency treatment is a promising improvement to the durability of earthen monuments. To understand the hydrophobic mechanism of the soil treated by Tung oil, geotechnical tests, including permeability test and water repellency test, in the laboratory were conducted on clay soil sampled from a site where Da Bao’en Temple was in Nanjing, China. Test results indicate that Tung oil film coated on the soil particles could well decrease the surface tension and free energy, providing waterproofing property without obvious change in esthetic appearance. Laboratory tests indicate that Tung oil treatment decreases the hydraulic conductivity and increases the water repellency of the soil. Water repellent treatment with Tung oil provides a new approach for earthen monument conservation under humid weather condition.

Breathable, Antistatic and Superhydrophobic PET/Lyocell Fabric

The objective of this study was to develop a breathable and antistatic superhydrophobic PET/lyocell fabric by simple finishing with polymeric fluorocarbon siloxane. To find an optimum concentration of the finish agent, four different concentrations of fluorocarbon finish agent were applied on three different types of fabrics; lyocell 100%, PET 100%, and PET/lyocell blend (50%/50%). Static water contact angle (WCA), shedding angle, and water repellency tests were measured to evaluate the wettability and hydrophobicity of treated fabrics. A PET/lyocell blend fabric treated with 40 g/L fluorocarbon finish agent exhibited superhydrophobic characteristics with WCA of 153.6° and shedding angle of 9.5° resulting from its lowed surface energy and multi-scale roughness. The effects of fluorocarbon finish on fabric moisture regain, electrostatic property, water vapor transmission rate (WVTR), and air permeability were evaluated as parameters for clothing comfort. PET/lyocell blend fabric treated with fluorocarbon exhibited significantly lower static electricity and higher moisture regain than the treated PET fabric. WVTR and air permeability were maintained after the finish. The blended fabric achieved noteworthy combination of antistatic and superhydrophobic properties. The functionality of finished PET and PET/lyocell fabrics, measured by WCA, shedding angle, and water repellency rate, was maintained until 10 washing cycles.

The effect of a novel booster (bisulfate adduct of polyisocyanate) on fluorocarbon chain re-orientation and substrate properties: Synthesis and finishing

Abstract This paper describes the fluorocarbon treatment of cotton fabric as a cellulosic substrate co-applied by a novel booster (bisulfate adduct of polyisocyanate) to improve its performance and repellent properties on the fabrics. The booster was synthesized from isocyanate groups blocked with sodium bisulfite and characterized by Fourier-transformed infrared analysis (FT-IR). The repellent properties of the cotton fabrics treated with fluorocarbon or fluorocarbon-booster were compared by FT-IR spectroscopy, water contact angle and 3M water repellency test before and after washing. The results indicated that bisulfate adduct of diisocyanate could be considered as a novel booster to create correct surface interface to maintain fluorocarbon performance without heat treatment and change the fabric properties from water repellency to water and oil repellency due to the decrease of the surface tension from 33 to 28.7 mN/m.

Comparative Analysis of Selected Fluorocarbon-Based Oil and Water-Repellent Finishes on Textiles

Efficacy of selected commercially available fluorocarbon-based finish agents, such as Oleophobol (Huntsman) Fluoroguard SX and Fluoroguard VOX (Britacel Silicones) Nuva HPU (Clariant) TG-581 (Resil) Aquaphobe-SNT (Akkshata), on cotton and polyester fabrics was studied with respect to water and oil repellency. All the finish agents exhibited excellent water- and oil-repellent properties on both kinds of fabrics. The contact angle of water on the finished cotton and polyester fabrics was found to be ≥ 140° Nuva HPU and Oleophobol gave cotton very good protection against rain. Except Aquaphobe SNT, all other finishes imparted excellent oil-repellent property to cotton. In the case of polyester, maximum oil repellency was achieved with Aquaphobe SNT and Fluorogard SX. The finished polyester fabric showed minimal absorption and better resistance to penetration of water as compared to cotton when subject to the Bundesmann water repellency test. There was a slight yellowing of the cotton fabric after the application of Oleophobol finish. There was no effect on the strength of the fabrics. The effect of these finishes on the crease recovery angle and the bending length of cotton was not significant, However, the polyester fabric became slightly stiffer after the application of the finishes. The crease recovery angle of polyester also increased after the application of these finishes. The finished fabrics showed good water repellency up to 15 washes. Oil repellency showed deterioration after only 5 washes and was partially retained up to 15 washes. Both water and oil repellency became negligible after 30 washes.

Molecular characterization of lipid fractions from extremely water-repellent pine and eucalyptus forest soils

There is little information available about the molecular composition of organic fractions with a possible bearing in soil water repellency. Extremely water-repellent forest soils developed on granites or schists, under vegetation of pine or eucalyptus, were used for sequential isolation of two lipid fractions: free lipid extracted with petroleum ether and ‘bound’ lipid obtained with the same solvent after 2M H3PO4 pre-treatment. Soil water repellency tests were carried out, and lipids were analyzed by gas chromatography/mass spectrometry (GC–MS). Free lipids in soils under eucalyptus consisted mainly of sesquiterpenes (globulol, aromadendrene, eudesmol and ledene) whereas soils under pine included diterpene resin acids (mainly dehydroabietic, pimaric and seco-dehydroabietic) and phenol. Free alkanes (C15 to C37) displayed homologous series typical in epicuticular waxes, whereas free fatty acids series showed bimodal distribution.‘Bound’ lipids consisted almost exclusively of fatty acids (mainly C16 and C18 acids), and alkanes (maximum at C27 or C28 and no even-to-odd C-number preference). Major compounds related to soil water repellency are typically found in higher plants and are not synthesized by microorganisms. After removing free lipids, soil water repellency decreased slightly but remained extreme. After extraction of bound lipids, the repellency considerably decreased, but did not disappear completely. As regards the effect of the lipid fractions in soil water repellency, it was clear the dominant role of the vegetation type in the case of free lipid, whereas for bound lipid, repellency mainly represents an emergent property arising from strong interaction between organic matter and the geological material.The results suggest that soil lipids only explain a part of the soil water repellency, which also depends on surface properties of the soil matrix, i.e., not only depends on hydrophobic coatings but probably of diffusion of hydrophobic cements into micellar associations self-organized into zonal structures in humus–clay matrix.

Novel superhydrophobic top coating on surface modified PVC-coated fabric

A superhydrophobic surface was created on poly(vinylchloride)-coated architectural fabric using spray coating method. Dispersions of nanoparticles and a flourochemical were prepared as top coating solutions. After spray-dry-cure process, contact angle, sliding (tilt) angle, 3M water repellency test and surface morphology were compared between uncoated and top coated PVC surfaces. The results indicated that a specific nano-TiO2 dispersion top coating produced a superhydrophobic layer on the top of the PVC surface with high contact angle (150°) and very low sliding angle (2°). Combination of two major requirements, the magnified of the degree of roughness and low surface energy, created self-cleaning effect on the PVC surface. Abrasion fastness of superhydrophobic top coating was improved by surface oxidation via UV–ozone surface treatments. Spectroscopic analysis demonstrated that formation of oxygenated functional groups has improved PVC wettability and adhesion. Results of artificial weathering test indicated no change in superhydrophobicity of top coated PVC.

Preliminary findings for the production of water repellent torrefied wood pellets with pyrolysis oil

AbstractTorrefaction of biomass has attracted considerable attention as a means to reduce biomass weight by 70% through removal of water and the hemicellulosic fractions while retaining most of the original high‐energy cellulose and lignin content. Current torrefied wood pellets or briquettes cannot be shipped in open containers exposed to precipitation because they are not highly water resistant. A highly water repellent pelletized product is required to allow bulk shipping of torrefied wood pellets or briquettes via open railcar or by barge. We have recently developed a binder produced from biomass components that imparts the water repellent quality required to produce a torrefied product that is able to be shipped in open containers. Crushing strength of the pellets produced with this binder are high at between approximately 700 and 1100 psi. Water repellency tests indicate that upon total immersion the pellets absorb water into available pores up to 2–5%. The pellets can then be dried without unacceptable loss of strength. © 2012 American Institute of Chemical Engineers Environ Prog, 2012

Re‐establishment of soil water repellency after destruction by intense burning in a Mediterranean heathland (SW Spain)

AbstractSoil water repellency has been conventionally considered as a fire‐induced effect, but an increasing number of studies have suggested that natural background repellency occurs in many soil types, and many of them have suggested that water repellency can be re‐established over time after being destroyed. An experimental fire was conducted to study changes of the soil surface during the first 18 months following intense burning. The main objectives of this paper are as follows: (1) to investigate in situ water repellency changes at three soil depths (0, 2 and 4 cm) immediately after burning; (2) to evaluate the medium‐term evolution of water repellency under field conditions; and (3) to outline the main hydrological consequences of these changes. Also, different water repellency tests (water drop penetration time, ethanol percentage test (EPT) and contact angle (CA) between water drops and the soil surface) were carried out for comparison purposes. Field experiments showed that soil water repellency was partly destroyed after intense burning. Changes were relatively strong at the soil surface, but diminished progressively with depth. Levels of water repellency were practically re‐established 18 months after burning. This suggests that water repellency in the studied area is not necessarily a consequence of fire, but can instead be a natural attribute. Finally, although limited in time, destruction of soil water repellency has important consequences for runoff flow generation and soil loss rates, and, indirectly, for water quality. Copyright © 2009 John Wiley & Sons, Ltd.

Using hyperspectral imagery to predict post-wildfire soil water repellency

A principal task of evaluating large wildfires is to assess fire's effect on the soil in order to predict the potential watershed response. Two types of soil water repellency tests, the water drop penetration time (WDPT) test and the mini-disk infiltrometer (MDI) test, were performed after the Hayman Fire in Colorado, in the summer of 2002 to assess the infiltration potential of the soil. Remotely sensed hyperspectral imagery was also collected to map post-wildfire ground cover and soil condition. Detailed ground cover measurements were collected to validate the remotely sensed imagery and to examine the relationship between ground cover and soil water repellency. Percent ash cover measured on the ground was significantly correlated to WDPT ( r = 0.42; p-value < 0.0001), and the MDI test ( r = − 0.37; p-value < 0.0001). A Mixture Tuned Matched Filter (MTMF) spectral unmixing algorithm was applied to the hyperspectral imagery, which produced fractional cover maps of ash, soil, and scorched and green vegetation. The remotely sensed ash image had significant correlations to the water repellency tests, WDPT ( r = 0.24; p-value = 0.001), and the MDI test ( r = − 0.21; p-value = 0.005). An iterative threshold analysis was also applied to the ash and water repellency data to evaluate the relationship at increasingly higher levels of ash cover. Regression analysis between the means of grouped data: MDI time vs. ash cover data ( R 2 =0.75) and vs. Ash MTMF scores ( R 2 = 0.63) yielded significantly stronger relationships. From these results we found on-the-ground ash cover greater than 49% and remotely sensed ash cover greater than 33% to be indicative of strongly water repellent soils. Combining these results with geostatistical analyses indicated a spatial autocorrelation range of 15 to 40 m. Image pixels with high ash cover (> 33%), including pixels within 15 m of these pixel patches, were used to create a likelihood map of soil water repellency. This map is a good indicator of areas where soil experienced severe fire effects—areas that likely have strong water repellent soil conditions and higher potential for post-fire erosion.

Modification of woolen fabrics through grafting with methacrylic esters

Grafting of methyl, n-butyl, n-decyl, and n-octadecyl methacrylate onto reduced woolen fabrics was carried out by using K2S2O8 and K2S2O8-LiBr redox system as initiators. The success of the grafting was proven by scanning electron microscopy, size exclusion chromatography, and infrared spectroscopy. The felting shrinkage and water-repellency tests were applied on the modified fabrics. Dyeing with an α-bromo-acrylamido and an aminoxanthene dye was carried out and the color-fastness tests were applied on the modified dyed fabrics. The influence of the grafted polymethacrylates on the shrinkproofing, water-repellency, and dyeing properties of the woolen fabrics was discussed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2399–2407, 1997

Morphology of perfluoroalkylacrylate/stearyl methacrylate polymers and their effect on water/oil repellency

The small-angle X-ray scattering technique was applied to study the morphology of a series of water-repellent terpolymers polymerized from a fluoro-component, a hydrocarbon-component and a crosslinking agent. The intraparticle homogeneity of the terpolymers was semiquantitatively determined from the small-angle X-ray spectra using a proposed structural model. The X-ray results were correlated to the water repellency test data using the AATCC test method 22-1989. The consistency of the polymerization reaction process as a function of the weight ratio of the fluoro-components is discussed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 903–909, 1997