Water-resistant Materials Research Articles

Water Resistant and Flexible MOF Materials for Highly Efficient Separation of Methane from Nitrogen

The highly efficient separation of CH4/N2 remains a great challenge, but it is vital to make the most of diverse natural gas resources and contributes to mitigating global warming. In this work, tw...

Highly elastic and flexible transparent conductive films derived from latex copolymerization: P(SSNa-BA-St)/PEDOT/graphene.

We reported an innovative transparent, elastic and flexible conductive composite materials P(SSNa-BA-St)/PEDOT/graphene which were prepared by using P(SSNa-BA-St) latex as template for PEDOT polymerization and graphene doping. This P(SSNa-BA-St)/PEDOT/graphene film exhibited highly transparent, good water resistance, low moisture adsorption, highly elastic and highly conductive properties, which can serve as a practical approach to fabricate the flexible, conductive and transparent films for wearable and implantable electronic devices, and photovoltaic cells.

Characterization of an Atypical Metalloproteinase Inhibitors Like Protein (Sbp8-1) From Scallop Byssus.

Adhesion is a vital physiological process for many marine molluscs, including the mussel and scallop, and therefore it is important to characterize the proteins involved in these adhesives. Although several mussel byssal proteins were identified and characterized, the study for scallop byssal proteins remains scarce. Our previous study identified two foot-specific proteins (Sbp7, Sbp8-1), which were annotated as the tissue inhibitors of metalloproteinases (TIMPs). Evolutionary analysis suggests that the TIMP genes of Chlamys farreri had gone through multiple gene duplications during evolution, and their potential functional roles in foot may have an ancient evolutionary origin. Focusing on the Sbp8-1, the sequence alignment and biochemical analyses suggest that Sbp8-1 is an atypical TIMP. One significant feature is the presence of two extra free Cys residues at its C-terminus, which causes the Sbp8-1 polymerization. Considering the fact that the no inhibitory activity was observed and it is mainly distributed in byssal thread and plaque, we proposed that this atypical Sbp8-1 may play as the cross-linker in scallop byssus. This study facilitates not only the understanding of scallop byssus assembly, also provides the inspiration of water-resistant materials design.

Nanofibrillated bacterial cellulose and pectin edible films added with fruit purees

Bacterial cellulose (BC) is a water resistant and strong material for edible films. Previous studies have been conducted on edible films containing fruit purees, but not using BC. In this study, films with or without fruit (mango or guava) purees were prepared using different ratios of nanofibrillated BC (NFBC) to pectin. The addition of fruit purees increased water vapor permeability (in about 13–18 times), reduced tensile strength (in more than 90%) and modulus (in about 99%), and increased elongation (in about 13 times), due to plasticizing effects of fruit sugars and matrix dilution by the purees. The partial or total replacement of pectin with NFBC resulted in improved physical properties, making the films stronger, stiffer, more resistant to water, and with enhanced barrier to water vapor. Fruit containing films based on pectin are suggested for sachets, whereas applications for food wrapping or coating may benefit from the use of NFBC.

Nitric acid-treated birnessite-type MnO2: An efficient and hydrophobic material for humid ozone decomposition

MnO2 catalysts are important for low-temperature removal of air pollutants. Sometimes the unavoidable moisture is not conductive to the desired reactions, therefore, water-resistant materials are desirable. However, the reported methods are not easily fulfilled for practical applications and the underlying mechanism for the improved hydrophobicity has not been clarified. In this study, highly water-resistant birnessite-type MnO2 was designed for humid ozone (O3) decomposition, which is important for alleviating global O3 pollution. The sample treated by nitric acid (H-MnO2) exhibited stable O3 conversion of ∼50% within 24 h under 50% of relative humidity (115 ppm of O3, 600 L·g−1·h−1 of space velocity, 25 °C). However, the pristine MnO2 was quickly deactivated with O3 conversion dropping to ∼10% within 30 min. Detailed characterizations show that higher amount of acid sites and oxygen vacancies together with their improved water-resistant properties facilitates adsorption and subsequent decomposition of humid O3 over the H-MnO2. DFT calculations demonstrate that compared with the pristine MnO2, oxygen vacancies were more easily formed over the H-MnO2, and the surface of the H-MnO2 was more hydrophobic and more attractive to O3 adsorption. Finally, a mechanism involving acid sites and oxygen vacancies for gaseous O3 decomposition was proposed.

Water-Resistant and Vapor-Permeable Material Based on Electrospun Fluoroplastic Membranes for Special Purpose Textile Items

Membrane-coated cloth items are very highly varied and include clothes and shoes for active vacations and tourism; special clothing for workers, firemen, and medical workers; military uniforms; and household (furniture fabrics) and technical (tents) items. They all should satisfy claimed requirements, e.g., protection from adverse environmental effects and removal from the space underneath the clothing of metabolic products and excessive moisture and heat depending on the load. The present article focused on the structural effect of an electrospun membrane and the composition of the glue layer on the operational properties of textile composites.

Serum concentrations of per- and poly-fluoroalkyl substances and factors associated with exposure in the general adult population in South Korea.

Per- and polyfluoroalkyl substances (PFASs) are ubiquitous contaminants found worldwide, including in South Korea. As a result, they are frequently detected in Koreans. However, there is limited representative data and information on potential sources in Korea. Therefore, we measured the serum concentrations of ten PFASs in nationally representative samples of the Korean population (n=1874, 18-69 years) and evaluated the factors associated with their exposure. Serum PFOS, PFDA, PFOA, and PFNA were detected in nearly all participants (83.1-99.9%). However, serum PFPA, PFHxA, and PFHpA were almost undetected (<0.5% of participants). PFOS had the highest population-weighted geometric mean of 10.23ng/mL (95% CI: 9.99-10.47), which was followed by PFOA with 2.85ng/mL (95% CI: 2.73-2.97) and PFDA with 2.17ng/mL (95% CI: 2.12-2.23). PFNA, PFDA, PFHxS, PFOA, and PFOS concentrations were higher in males (p<0.001) and older adults (p<0.001). PFNA was higher in those who used wax, polish, and water-resistant materials (adjusted proportional change=1.14; 95% CI: 1.08-1.22), and those who ate cooked fish (1.16; 95% CI: 1.03-1.31) compared to those who ate nearly no fish. PFDA was higher in those who used herbicides and pesticides (1.05; 95% CI: 1.02-1.09), those who drank beverages in a plastic bag on a daily basis (1.10; 95% CI: 1.03-1.19), and those who ate raw fish (1.15; 95% CI: 1.03-1.29) or cooked fish (1.13; 95% CI: 1.05-1.23) compared to those who ate nearly no fish. PFHxS was higher in those who used traditional Korean health supplement foods (1.08; 95% CI: 1.01-1.15). PFOA was higher in those who used plastic wrap in a microwave daily or weekly (1.08; 95% CI: 1.00-1.16), and those who used disposable paper cups (1.07; 95% CI: 1.01-1.13). PFOS was lower in underweight participants (0.84; 95%CI: 0.75-0.93) compared to those who were obese, and higher in those who exercised regularly (1.08; 95% CI: 1.03-1.14) or irregularly (1.06, 95% CI: 1.01-1.12) compared to those who did not exercise. Subjects who used severely damaged Teflon appliances had lower concentrations of PFOA (0.78, 95% CI: 0.65-0.95), while regular use of Gore-Tex goods was related to higher PFNA (1.15, 95% CI: 1.03-1.28) and PFDA (1.11; 95% CI: 1.02-1.20) levels. These findings suggest that most Koreans are frequently exposed to PFASs, and that serum concentrations of PFASs vary with age, sex, and exposure factors.

Cellulose fiber based fungal and water resistant insulation materials

AbstractThe development of thermal insulation materials from sustainable, natural fibrous materials is desirable. In the present study, cellulose fiber based insulation foams made of bleached chemi thermo mechanical pulp (CTMP) have been investigated. To improve water resistance, the foams were impregnated with hydrophobic extractives from the outer bark of birch (Betula verrucosa) and dried. The surface morphology of the foams and the distribution of the deposited particles from the extractives were observed by scanning electron microscopy (SEM). The modified foams showed improved water resistance, as they did not disintegrate after immersion in water for 7 days, whereas the unmodified foam did. Compared to the unmodified foam, the modified foams absorbed 50% less moisture within 24 h. The modification had no negative effects on the thermal insulation properties, fungal resistance or compressive strength of the foams. The proposed approach is simple and can be easily integrated into plants working based on the biorefinery concept.

Influence of complex chemical additives on the water resistant silicate materials

In this paper, it has been established that the use of silica fume, low-base slag and calcium hydroxide to modify clays in constrained contact conditions leads to an increase in the number of contacts between the particle components and provides the conditions for the formation of strong contacts and the formation of dense microstructures, and therefore reduces its water absorption and increases water resistance of unburned building materials based on local aluminum silicate raw materials.

Correlation of Ship Sanitation with Cockroach Density on Motor Vessel Docked in Port of Tanjung Perak Surabaya

Abstract: Based on data from Port Health Offi ce Class I Surabaya in 2012, 42 (1.66%) of 2.521 ship that were inspected was found vectors. Sanitation assessment data were found cockroach in July 2015, 9 (4.20%) of 214 ships, in August 15 (8.02%) of 187 ships, and in September 16 (8.88%) of 180 ships. Meanwhile Kepmenkes 431/2007 states that all water transportation have to be clean from vector and rodent. The objective of this study was to analyze correlation between ship sanitation and cockroach density. The design of this study was cross sectional. Samples was 30 ship that were docked at Port of Tanjung Perak Surabaya in October 2015. Sampling method was using accidental sampling. Data were obtained by questionnaire and observation Data were analyzed with Spearman correlation test. The result showed that 40.00% had high risk of health disorder and 91.67% of 40.00% was found high cockroach density There was a signifi cant correlation between ships sanitation and cockroach density. Not only all bins were not equipped with lid and water resistant materials but also poor personal hygiene of food handlers. It can be concluded that there was a correlation between ship sanitation and cockroach density. It is suggested to improve and maintain ship sanitation by equipping all of bins with lid and water resistant material and by increasing the personal hygiene of food handlers.Keywords: vessel sanitation, cockroach density, motor vessel

Polymerisation and Oxidation of Docosahexaenoic Acid

Oils rich in polyunsaturated fatty acids, such as linseed oil, can oxidise to form polymers. These can be used as protective coatings and act as an alternative to those derived from petrochemicals. Such renewable source oils usually require the addition of metal ions as catalysts of the polymerisation process and/or the partial pre-oxidation of the oil before use. We hypothesised that increasing the unsaturation of the oil would result in polymerisation occurring without such requirements. Of the oils tested only docosahexaenoic (DHA) acid and boiled linseed oil (BLO) (which contains metal ion catalysts) demonstrated significant increases in viscosity during the incubation period, with both oils thickening at approximately the same rate. The production of the lipid peroxidation product propanal was much greater during DHA polymerization compared to that of BLO. DHA and BLO formed a water proof coating on cotton cloth although DHA formed more brittle coatings than BLO. Our results demonstrate that the greater extent of lipid peroxidation of high purity DHA allows it to polymerise in air to form a water resistant material similar to that obtained using boiled linseed oil but without the addition of toxic metal ion catalysts. Further investigation of this substance as a renewable component of coating materials may be warranted, particularly for applications requiring low toxicity such as those in contact with foodstuffs.

The Upshot of the 2012 Flooding on Structural Components and Fabrics of Buildings at Ogbaru, Anambra State Nigeria

The study examined the effect of the 2012 flooding on structural components and fabrics of buildings at Ogbaru Local Government Area of Anambra State. It also examined the heights of the ground floors and foundations of the buildings respectively in relation to the height of the flood. Questionnaire survey on the selected households and physical examination on the building structures were carried out. The study revealed that most buildings in the area were either fully or partially submerged during the flood incidence. it further revealed that there no very severe damages on the structural components of the buildings, despite that most of the buildings have low ground floor levels (74%) and shallow foundations (68%) below 300mm. However, building fabrics and elements such as finishes and electrical fittings were severely damaged when the flood height rose 1 metre above the ground floor level. More so, the study revealed that the flood severely damaged both the structural components and fabrics of very old, weak and mud buildings. Based on this, the study recommended that building constructors in the area should raise the ground floor level of their building projects to at least 1 metre above the ground level. It also recommended suspension of buildings on plinths and use of deep stripe or raft foundation. The use water resistant materials and components such as paints, doors, windows and electrical fittings and incorporation of oversite concrete as floors while building new structures or refurbishing existing ones are also recommended.

Strength development and micro-mechanism of magnesium oxychloride cement concrete

This paper presents the feature of magnesium oxychloride cement and its particle. Water-resistant admixture and other inorganic materials (silica fume, fly ash and slag) with mix proportion were added to the mix proportion to improve the mechanical properties of magnesium oxychloride cement concrete. By recording the uniaxial compressive strength of concrete at 7–128 days, the influences on the early and late strength of magnesium oxychloride cement caused by different inorganic materials and varied consumption of magnesium chloride solution were analysed. It is shown that the early strength development is fast and the strength with fly ash performs the highest strength; the late strength of concrete reduces because of the scumming of magnesium oxychloride cement, but the strength resumes. Using X-ray diffraction, scanning electron microscope and energy dispersive X-ray spectroscope to investigate the micro-mechanism, the dense gel phase is found in magnesium oxychloride cement concrete with fly ash, which led to the advantage in compressive strength over other samples.

Water-Resistance Material from Fibers and Acrylic Emulsion Terpolymer

Styrene (SM), methyl methacrylate (MMA), and butyl acrylate (BA) were used to synthesize a polyacrylic emulsion by core-shell emulsion polymerization. The solid content of the emulsion reached 40% using reasonable reactive emulsifier contents and feeding modes. Then, two kinds of fibers (recovered and hardwood fiber) were respectively dispersed, coated, and dried with emulsion. Finally, fiber-based water-resistant material was successfully fabricated. The experimental results showed that under the conditions of a mass ratio of polyacrylic emulsion to fiber of 2:1, the Cobb value of the material reached 7.1 g/m2 and 10.8 g/m2 respectively. Cobb value of recovered fiber material was more stable than hardwood fiber, and stayed in a lower variation scope on the whole. Using scanning electron microscopy (SEM) to observe the surface morphology of products. The SEM results proved that, the polyacrylic emulsion filled the gaps between fibers, decreased the porous structure. This filling effect led to a continuous structure, and kept the water from infiltrating inside of the material. On the other hand, for the short fiber in recovered fiber material arranged closer, the water resistance of the material was further enhanced.

Deducing the Macromolecular Organization of Arabidopsis Thaliana Leaf Cuticles by Solid-State NMR

Terrestrial plants regulate environmental interactions via insoluble polymers assembled in their epidermal and/or peridermal cell walls. The plant cuticles with waterproofing and antimicrobial capabilities represent a unique class of biological assemblies composed of ester-linked and insoluble constituents such as biopolyester cutins, lipid waxes, and chemically recalcitrant cutans. Solid-state nuclear magnetic resonance (NMR) offers a powerful technique to probe the structural and dynamical properties of these geochemically important and structurally amorphous biological systems that can also motivate the engineering of water-resistant bioinspired materials from renewable sources. Based on key genes and biosynthetic pathways identified in Arabidopsis thaliana leaf cuticles, our current solid-state NMR study delineates compositional variations and multiple-timescale (µs-ns) dynamics for several genetically tailored and insoluble plant cuticle systems, linking macromolecular organization with protective performance and operational design.

Bioadhesive emulsions for control release of progesterone resistant to vaginal fluids clearance

The aim of this study is to propose that mucoadhesive vaginal emulsions can be able to resist the clearance effect of vaginal fluid and to have an effective control release of progesterone. With this goal, silicon derivative, cyclomethicone pentamer, was selected as the bioadhesive and water resistant material. In order to obtain a system which is insensitive to the dilution of aqueous fluids, water in silicone (W/S) emulsions were prepared and different proportions of cyclomethicone as well as 8% or 15% w/w of progesterone were employed. The rheological, mechanical and mucoadhesive properties of emulsions were characterized and the drug release was measured for each formulation. Mucoadhesive behavior was determined and the influence of simulated vaginal fluid (SVF) at bioadhesion was assessed using three commercial mucoadhesive vaginal gels (Crinone®, K-Y jelly® and Zidoval®) as the bioadhesive references. All assayed emulsions have good rheological and mechanical properties and their consistence and viscosity increase when the proportion of the internal phase increases. Related to mucoadhesion, in the absence of SVF, W/S emulsions showed similar bioadhesive levels like the commercial formulations. However, in the presence of SVF, W/S emulsions are able to keep their mucoadhesive properties while the marketed references drastically lose their consistency and adherence to the vaginal mucosa. Drug release profiles from W/S emulsion show that progesterone is released with pseudo-order zero kinetics and a constant release rate is maintained for at least two weeks. The results of the in vivo studies developed in rats show that after a single vaginal administration, bioadhesive W/S emulsions increase the uterine tissue progesterone levels in young and postmenopausal rats. Moreover in postmenopausal rats, they provide high uterine levels of progesterone compared to the bioadhesive-marketed gel used as a reference. Therefore, W/S emulsions have an interesting potential as bioadhesive vaginal delivery systems for drug administration.

WATERPROOF ANTI-EXPLOSIVE POWDERS FOR COAL MINES

Abstract Limestone powder characterized by hydrophobic properties is used as an anti-explosive agent in coal mining industry. Unfortunately, the standard method of producing such powder by milling limestone with stearic acid is practically unprofitable in many modernized quarries and plants, and sometimes literally impossible due to the introduction of technological changes and implementation of modern mills. Then new methods of hydrophobization of limestone surfaces ought be searched. In the work two methods hydrophobization: from the stearic acid vapour phase and from silicone solutions are proposed. Lime dust from the Czatkowice Quarry of Lime was used as a raw material during investigations. It is a good agent for research because it is possible to compare the properties of samples modified in this work to the properties of anti-explosive lime powder (Polish Standard, 1994) used in mining industry in Poland. The first technique of limestone powder hydrophobization was carried out in an apparatus of own design (Vogt, 2008, 2011), and it consisted in free sedimentation of the powder layer dispersed by stearic acid vapour in powder counter current flow. The second way of modification consisted in mixing in the evaporating dish substrates: limestone powder and dope - silicone solution - Sarsil® H-15 (Vogt &amp; Opaliński, 2009; Vogt &amp; Hołownia, 2010). Evaluation of properties so-obtained waterproof powders was carried out according to the Polish Standard, as well as using original powder determination ways, with the Powder Characteristic Tester (Index tables, Tablets &amp; Capsules, 2005). Moreover water vapour adsorption isotherms were obtained and the thermal decomposition of powder was made. All modified samples acquired the hydrophobic character. Therefore we can state that the both proposed methods of hydrophobization of the limestone powder are useful. The parameters obtained with the use of Powder Characteristics Tester enable us to make a characterization of limestone properties not only as a water resistant material but also from the cohesion point of view. On the base of TG, DTG or DTA and EGA curves for all investigated materials was stated that the character of the thermal decomposition of modified samples is the same as this one for raw powder, what is profitable for application of hydrophobized powders as an anti-explosive agent.

Water-Resistant Material from Recovered Fibers and Acrylic Emulsion Terpolymer

Styrene (SM), methyl methacrylate (MMA), and butyl acrylate (BA) were used to synthesize a polyacrylic emulsion by core-shell emulsion polymerization. The solid content of the emulsion reached 40% using reasonable reactive emulsifier contents and feeding modes. Then, the emulsion and a fiber were dispersed, coated, and dried together. Finally, fiber-based water-resistant material was successfully fabricated. The experimental results showed that under the conditions of a monomer mass ratio of 1:1:1 and a mass ratio of polyacrylic emulsion to fiber of 2:1, the Cobb value of the material reached 5.0 g/m2. The tensile strength, elongation, and breaking length were 7.4225 kN/m, 1.0%, and 11.706 km, respectively. Using scanning electron microscopy (SEM) to analyze the surface morphology and internal structure of products, the reasons for the high water resistance of fiber-based material was due to the bonding and filling effects of the polyacrylic emulsion on the fibers. For tightly bound fibers, the porous structures formed in fiber-based boards were reduced. On the other hand, the polyacrylic emulsion filled the gaps between fibers. This filling effect led to a continuous structure, and the water resistance of the material was further enhanced.

Protective camouflage cover

Uniformity of protective camouflage installations significantly increases survivability of tanks on the move. This installation prevents an enemy from distinguishing a tank from a car or an empty trailer. A camouflage cover made of multilayer water-resistant material makes anti-tank shaped charge projectiles pre-detonate. Since most projectiles are designed for attacking ERA, the first detonation hits the camouflage cover instead of the armour. When the second detonation hits the ERA, its explosion neutralizes the shaped charge jet. This structure is considerably cheaper and much more effective than rubber protection models. The article analyses anti-tank combat means, 'smart' missile guidance methods and methods of fighting means of attack. It also gives methods of fighting 'smart' projectiles and the applications of this protective camouflage structure.

Properties of High Pressure Water Hydraulic Components with Modern Coatings

Water hydraulics is coming back as an alternative to oil and other not environment friendly working fluids used in a very wide range of fluid drive and control systems. The cost of water resistant materials for components is one of the barriers preventing the wide use of water hydraulics, especially moving parts such as pump pistons, surface of cylinder tubes and rods, poppet and seats, etc. to avoid corrosion. One of the common solutions is to use stainless steel there, where it can cooperate with other nonmetallic material such as plastic or other noncorrosive metallic composite to reduce friction. Thus some of research was directed to elaboration of special coating for covering surfaces in critical regions of water hydraulic components. The paper describes results of pilot research on selected components where such coating were introduced on regular carbon steel parts, same as used for oil hydraulics. First part of the article contents description of coating technology and some characteristics of coating layers. Second quotes selected results of conducted by authors research on coated hydraulic cylinders and poppet valves.