Papers by Keyword: Hydrophobicity

Abstract: New materials based on oligooxidridsilmethylensiloxysilane nanostructured with ethyl ester of orthosilicic acid – tetraethoxysilane have been studied in the research. Tetraethoxysilane introduction into the composition is supposed to cause its decomposition up to nanoparticles of silicon oxide. The alkoxysilane hydrolytic destruction kinetics and the impact of the composition and nature of the polymer composition components on the physical properties have been studied. Atomic force microscopy was used to study the structurization kinetics of the polymer composition. The composition hydrophobicity was determined by the edge wetting angle. To study the adhesion characteristics of the obtained material, the method of disc separation from the substrate has been used. The relative rigidity has been determined by a pendulum device M3. Atomic force microscopy revealed the presence of nanoscale neoplasms (at average of one hundred twenty per one square micrometer) in diameter from two to five nanometers in the surface structure of the composition, modified with tetraethoxysilane. Herewith the physical properties of the material change: rigidity increases, the edge angle of wetting increases as well. The studied nanostructured compositions can also be applied. For example – they can be used as a protective coating with a set of special properties, such as high hydrophobicity.

Abstract: Epoxy resin (EP) mortar usually used to repair the cracking of concrete structure under damp environment, but EP is extremely flammable, thus it’s extremely imperative to design a novel multifunction EP grouting materials with flame retardancy and waterproofness for the practical application. Targeting ingenious decoration of EP grouting materials, multiple flame retardant elements (phosphorus, nitrogen and fluorine) are concurrently introduced into a fire retardant and the fire retardant defined as DDM-FNP. The obtained DDM-FNP/EP grouting composite possess high thermal stability, flame retardancy and hydrophobicity. The limiting oxygen index (LOI) value of DDM-FNP/EP composites has a significant improve, which is increased from 26.7 (EP-0) to 35.8 (EP-4). Composites with more than 10 wt% of DDM-FNP could pass UL-94 V-0 rating without dripping. Compared with EP-0, the PHRR and THR of EP-4 are decreased by 31.1% and 21.6%, respectively. In addition, due to the introduction of the F element, the water contact angle of EP composites is changed from 75.2° (hydrophilicity) to 98.6° (hydrophobicity) after the introduction of a certain amount of DDM-FNP flame retardant. Therefore, this work provide a new perspective to design a multifunction EP grouting composite and improve the value of practical application on seepage prevention of tunnel.

Abstract: The article discusses aspects of the production and use of composites based on carbon-filled cement matrices. It is shown that the main problem in the technology of such composites is the regulation of the processes of structure formation and uniform distribution of the electrically conductive phase throughout the volume, to ensure stable electrical characteristics of the material. A method for solving the problem of improving the physical, mechanical and thermal properties of carbon-filled Portland cement composites by regulating the surface properties of carbon fillers, in order to reduce their concentration in the composite and the content of the aqueous phase, is proposed. It is shown that the modification of the carbon filler surface using the water-repellent agent PMS-20 reduces the adhesion work at the interface, which makes it possible to reduce the concentration of the electrically conductive phase in the composite and improve its physical, mechanical and thermal characteristics.

Abstract: Introduction. Synthetic coral scaffold is fabricated the mimicking of natural sea coral as a scaffold for bone regeneration [1]. Scaffold is performing functions as a micro environment for cells attachment, growth, proliferates, differentiates until it can form new bone tissue. The proper design is needed to produce the scaffold [2]. The purpose of this study was to investigate the characteristics of synthetic coral scaffold for micro environment of cells by observing cell attachment, hydrophobicity, and scaffold porosity. Experimental. Synthetic coral scaffold consists of bovine gelatin dan CaCO3 by weight, the concentration that be used are 4:6. Sodium citrate is used as dispersant. Thick film like scaffold was prepared for this study [1,3]. Vero cell line was used for observing cell attachment to investigate the biocompatibility the scaffold. The hydrophobicity was observed with distilled water droplets dripped on the scaffold surface, be analyzed in a photograph taken by the camera and then measured the angle. Percentage of porosity was measured using Archimedes law in absolute ethanol. Results and Discussion. Vero cells attached successfully into scaffold. Cell viability percentage is 91,77 % from the absorbance value of the MTT assay. It presented that the scaffold has biocompatibility character. However, the percentage of porosity is 55,85%, so the scaffold has enough porosity for cell attachment. Porosity serves for the diffusion of nutrients, gases and removes the residual metabolism resulting from cell activity that has grown on scaffold. The good porosity value of the scaffold is 50-90%. The higher the porosity value the better the scaffold. Hydrophobicity scaffold appears from the contact angle of 81.4°, the cohesion is greater than the adhesion. This shows the greater synthetic coral scaffold hydrophobicity, which is affected by surface roughness from scaffold porosity. The greater hydrophobicity will also prolong the degradation of the scaffold, thereby enabling cells to proliferate, differentiate and produce bone matrix. Conclusions. Synthetic coral scaffold provides the micro environment for cell, high hydrophobicity allows longer degradation for proliferation and differentiation of bone cells, and porosity that allows cells to be inserted within the scaffold.

Abstract: Polymer films are plasma treated to improve surface properties making them hydrophilic or hydrophobic. Expanded polytetrafluoroethylene (ePTFE) is used in a wide variety of applications but only a few report on plasma treated ePTFE. Within these very few studies on ePTFE, the use of ultra-thin membrane could hardly be found. The purpose of this study is to investigate the effect of plasma treatment (Argon-Oxygen) on the hydrophobicity of ultra-thin ePTFE membrane (4um thickness). This study used nine (9) experimental legs of ePTFE subjected to respective plasma power (150W, 315W and 600W) and exposure time (300s, 450s and 600s) for each leg. Contact angle was measured prior and after subjecting to plasma condition using contact angle meter. Energy pen was also used to verify its hydrophobicity. Scanning electron microscopy (SEM) with 10,000x magnification was used to check for any change in surface after exposing to each condition. The findings showed that the membrane surface changed after exposure to plasma. All legs became hydrophilic. 102◦ contact angle was measured from raw sample, but the samples exposed to plasma had contact angles ranging from max of 68◦ to min of 48◦. The results showed that the degree of surface change could be correlated to the plasma parameters applied. Furthermore, the highest radio frequency (RF) power applied resulted to contact angle in the range of 60◦ while the lowest RF power applied resulted to the lowest contact angle, in the range of 40◦, measured. On the other hand, no particular trend was observed based on exposure time. Based on the gathered results, the ultra-thin ePTFE, in order to maintain its hydrophobicity, must not be applied with argon-oxygen plasma treatment. However, if the ultra-thin ePTFE is to be made hydrophilic, argon-oxygen plasma treatment could be applied while adjusting the plasma parameters to meet the desired hydrophilicity level.

Abstract: Thin film coatings of graphene oxide (GO) onto copper pipe was investigating using electrophoretic deposition (EPD) technique. Graphite oxide was produced from graphite powder by chemical oxidation using modified Hummers' method. An aqueous colloidal suspension of graphene oxide was prepared by exfoliation of the graphite oxide via ultrasonic treatment. GO coatings were deposited on copper pipes through EPD from GO aqueous suspension. The EPD parameters such as voltage, time and particle concentration were optimized to obtain uniform GO coatings. The optimal EPD conditions for well-formed deposits were observed when the operating voltage was equal to 30 V and 90 s deposition time. The thin film coated copper pipe was characterized using various techniques such as SEM, XRD and contact angle. XRD confirmed that GO was reduced during the EPD process itself due to the removal of oxygen containing functional groups. SEM images elucidated the formation of GO thin layer onto copper pipe with thickness 5 μm. The contact angle improved from 70° for bare copper to 102.4° for GO coating.

Abstract: Nowadays the use of multifunctional nanomaterials has significantly increased with interesting applications for the cultural heritage conservation sector, leading to the definition and use of products with innovative properties. Therefore, a preliminary validation of the performances and behavior over time of these treatments becomes an unavoidable key point for a correct use of these products before being applied to historical materials, in order to avoid irreparable damage over time. In this direction, the aim of this study was to evaluate the effectiveness of the treatment with multifunctional nanostructured products on Apuan marble. The focus of the work was to test methods to accelerate aging, in order to simulate different environmental agents of degradation to which marble in historical buildings can be exposed. Stone samples were examined after exposition to high temperature cycles in a muffle furnace, treatments in saline solution, cycles of thermal shock and aging by SO₂ action in presence of humidity. After each artificial aging cycle, changes in appearance were noted and chemical-physical properties were measured in order to compare differences between fresh and treated samples. The protective qualities of the coatings were evaluated using the following tests: contact angle; photocatalytic properties by methylene blue degradation tests; photodegradation kinetics of pollutants under UVA irradiation. Before and after the treatments, scanning electron microscopy equipped by microanalysis detector (SEM-EDS) was also used to evaluate changes in the surface morphology of the samples. The results showed effects of degradation in the rock samples due to aging after each test and all the products applied to the sample surface seemed to be very efficient in relation to their functions.

Abstract: The method of obtaining magnetic petroleum sorbent for petroleum products spills cleanup from water surface, based on the mixture of waste kieselghur sludge from oil extraction industry and a ferromagnetic component - the finely-dispersed iron-ore concentrate (magnetite), has been suggested. It has been demonstrated that after the waste kieselghur sludge thermal modification in the temperature interval 430-500°С the burn-out of the organic matter is not complete – there remain the wax fractions of wax-like substances, contained in it. The obtained material becomes hydrophobic and oleophilic. The introduction of magnetite in amount of 10% provides the maximum oil-absorbing capacity of the petroleum sorbent – 3.05 g/g without reducing its hydrophobic properties. The value of the wetting angle amounts to 150°, and the water absorption is very low – no more than 2.1%. The optimal temperature of the magnetic petroleum sorbent production is 450°С. The obtained material in its petroleum-saturated state is highly buoyant within 24-120 hours, which provides enough time to clean up the water surface from petroleum products and to collect the sorbent.

Abstract: Coating application is a promising direction of introduction into medical practice. The proposed method is aimed at modifying the surface of various implantable polymer assemblies and parts coming into direct contact with blood. This will prolong the life of the implants in the body. In this paper several variants of carbon fine-dispersed fillers are considered, namely: carbon nanotubes, finely dispersed highly oriented pyrolytic graphite, microspheres of titanium carbide. The coatings were applied by a method that did not require the heating of the polyurethane substrate. In this work, the optimal form factor of the alloying additive was investigated in a polymer (polyurethane) bond applied to the surface of the article.

Abstract: Composite coatings have been obtained by plasma electrolytic oxidation method and subsequent treatment with fluorine-containing compound: suspension of superdispersed polytetrafluoroethylene. A method of formation of the protective coating by dipping into the suspension of organofluorine compound with subsequent heat treatment has been developed. The surface morphology of samples, their electrochemical and tribological properties, as well as wettability have been studied. Formed composite coatings reduce the corrosion current density and wear more than two orders of magnitude in comparison with the base PEO-coating. Additionally, composite layers have hydrophobic properties: for polymer-containing coatings the value of contact angle attains to 143±2°.