Adhesion Strength of Organic-Inorganic Terpolymers Containing Nanostructured Poly(Titanium Oxide) with Self-Cleaning Properties to Different Materials

Optically transparent organic-inorganic terpolymers based on poly (titanium oxide), hydroxyethyl methacrylate and organic monomers of the vinyl and (meth) acrylic series (acrylonitrile, butyl methacrylate, vinyl butyl ether, 2-ethylhexyl acrylate) were obained as a coating on silicate glass, polycarbonate, touch-up paint and metal. Materials’ light transmittance in the visible spectral range is 87 - 92% depending on the composition. The adhesion of terpolymers’ thin layers to substrates of various natures was investigated under shear deformations and by the lattice notch method according to ISO 15140. It was found that it is necessary to selectively excerpt composition of terpolymers in accordance with the nature of the substrate for creation adhesive durable coatings. The most durable coatings are formed on glass, polycarbonate and automotive enamel. It was revealed that the nature of the substrate and the composition of organic-inorganic terpolymers affect the hydrophobicity of the coatings and their ability to hydrophilize under the influence of UV-irradiation. The contact wetting angle of coatings with water, on average, reversibly varied within ~ 90 ° ↔ ~ 30 °.

Influence of a Hydrophobic Emulsion on the Surface Properties of Coatings of Water-Dispersion Acrylic Paint

The existing methods of confering hydrophobic properties to various building materials are considered. Obtaining special, including hydrophobic, properties of water-emulsion paints is a very relevant task. Previously, a method was developed for producing an emulsion of a polysiloxane stabilized with polyvinyl alcohol. The paper describes the possibility of using a hydrophobisating emulsion of polyhydrosiloxane as a functional additive for an acrylic water-dispersion paint. This emulsion is capable of forming coatings on dense and porous surfaces with an adjustable contact angle up to 105 °. The use of this emulsion, with its sufficient coalescence for volumetric hydrophobization of coatings, makes it possible to obtain a high contact angle on the surface. In the paper, it was assumed that the partial introduction of small amounts (up to 10 %) of a hydrophobizing emulsion into water-dispersion paints would allow achieving the contact angle of wetting for similar coatings consisting exclusively of emulsion. It is shown that the introduction of small amounts of a hydrophobizing emulsion with an auxiliary coalescing action of ethylene glycol makes it possible to impart hydrophobic properties to the surface of the resulting coating. When the optimum concentration of ethylene glycol in the coating is reached, dissolution and transport (yield) of polysiloxane to the surface is ensured. The research carried out made it possible to develop a paint composition with a hydrophobizing emulsion with a contact wetting angle of about 100 °, which ensured the hydrophobicity of the previously hydrophilic coating of a water-dispersion acrylic paint.

INFLUENCE OF MICROBIAL CARBONATE MINERALIZATION ON HYDROPHOBICITY OF A CEMENT STONE SURFACE

The effect of microbial carbonate mineralization on increasing the hydrophobicity of the cement stone surface is theoretically justified and experimentally confirmed. Based on experimental studies and analysis of literature data, the main stages of microbial-induced sedimentation of calcium carbonate on the surface of a cement stone are formulated. Changes in the morphology of the cement stone surface due to crystalline new formations formed during biomineralization in the postgenetic period are described. It is shown that biocolmatation of the interstitial space of a cement stone by crystalline new formations leads to an increase in hydrophobicity, as evidenced by an increase in the contact wetting angle. The relationship between the change in the concentration of calcium in neoplasms and the average value of the contact wetting angle on the surface of the cement stone from the type of bacterial culture is established. According to chemical and morphological analysis of bioinduction tumors on the surface of samples and also evaluation of changes of the contact angle compared to the original index for cement, bacterial cultures are ranked in order to increase the efficiency of use for sedimentation of calcium carbonate with their participation, as well as increase of cement materials hydrophobicity in the following sequence: Sporosarcina pasteurii  Bacillus megaterium  Lysinibacillus sphaericus  Bacillus pumilus.

FORMALIZATION CONCEPT OF A CAPILLARY OF THE CIRCULAR TRANSVERSE SECTION TAKING INTO ACCOUNT THE CONTACT WETTING ANGLE

Расчеты процессов распределения и переноса жидкости в пористых средах основаны на учете ее капиллярных свойств в поровом пространстве. От степени заполнения капиллярной жидкостью порового пространства зависит интенсивность протекающих в нем процессов. Капиллярной жидкостью заполняются поры только малого размера. Поры большего размера остаются незаполненными. Однако отсутствует аналитическое обоснование величины поперечного размера поры с учетом краевого угла смачивания, больше которого она не может заполняться жидкостью за счет капиллярных сил. С этих позиций рассмотрено понятие предельного поперечного размера капилляра в условиях его смачивания жидкостью. Получена расчетная формула наибольшего поперечного размера модельных пор круглого поперечного сечения, относящего их к капиллярам, с учетом величины краевого угла смачивания. Предложено использовать параметр, названный удельным поверхностным натяжением λ, для оценки влияния комплекса физических констант жидкостей на величину предельного поперечного размера капилляра. Параметр λ представляет отношение коэффициента поверхностного натяжения жидкости к силе тяжести ее единичного объема. По полученной формуле для ряда жидкостей выполнены расчеты капилляров предельных размеров как функций углов смачивания. Результаты исследований могут быть использованы для повышения эффективности расчетов тепломассообмена в пористых средах в пищевых производствах и других аналогичных задач. The calculations of the processes of saturation and transfer of fluid in porous media are based on taking into account of its capillary properties in the pore space. The intensity of the processes occurring in the pore space depends on the degree of filling of it by capillary liquid. Only small pores are filled with capillary fluid. Larger pores remain unfilled. However, there is no analytical justification for the transverse pore size taking into account the wetting angle of the meniscus, more than which the pore cannot be filled with liquid by capillary forces. With this in mind, the concept of the limiting transverse size of a capillary for a liquid is considered. The calculated formula for the largest transverse size of model pores of circular transverse section, which relates them to capillaries, taking into account the value of the contact wetting angle, is obtained. It is proposed to use a parameter called specific surface tension λ to evaluate the effect of a complex of physical constants of liquids on the value of the maximum transverse size of the capillary. The parameter λ represents the ratio of the surface tension coefficient of a liquid to the gravity of its unit volume. According to the obtained formula for a number of liquids, calculations of capillaries of limit sizes as functions of contact wetting angles are performed. The research results can be used to improve the efficiency of calculations of heat and mass transfer in porous media in food production and other similar tasks.

Durability of the Exterior Transparent Coatings on Nano-Photostabilized English Oak Wood and Possibility of Its Prediction before Artificial Accelerated Weathering

Changes in surface material characteristics can significantly affect the adhesion and overall life of coatings on wood. In order to increase the durability of transparent exterior coatings, it is possible to use the surface modification of wood with UV-stabilizing substances. In this work, selected types of surface modifications using benzotriazoles, HALS, ZnO and TiO2 nanoparticles, and their combinations were applied to oak wood (Quercus robur, L.). On such modified surfaces, the surface free energy, roughness, and contact wetting angle with three selected types of exterior transparent coatings were subsequently determined. An oil-based coating, waterborne acrylic thick layer coating, and thin-layer synthetic coating were tested and interaction with the aforementioned surface modifications was investigated after 6 weeks of accelerated artificial weathering. The results of changes in the initially measured surface characteristics of the modified oak wood were compared to the real results of degradation of coatings after artificial accelerated weathering. The positive effect of surface modification, in particular the mixture of benzotriazoles, HALS, and ZnO nanoparticles on all kinds of coatings was proven, and the best results were observed in thick-film waterborne acrylic coating. The changes in the measured surface characteristics corresponded to the observed durability of the coatings only when measured by wetting using drops of the tested coatings.

Рrospects of research development and new applications of concentrated artificial latexes

The phenomenon of strong stabilization of concentrated aqueous dispersions (emulsions) of polymers by colloidal particles of organic nature (microparticles of synthetic latexes), not accompanied by a significant increase in effective viscosity, opened, firstly, the possibility of carrying out the processes of pigmenting them at low energy costs with a maximum yield (dynamic state, meets the conditions of intensification of heterogeneous chemical-technological processes) and, secondly, determined the directions of further research in this area. So, in contrast to the classical method of emulsion stabilization by mineral microparticles adsorbed directly on the surface of their droplets, microparticles of organic origin interact with them through an interlayer of the dispersion medium, localizing in the immediate vicinity of the dispersed phase and thus maintaining a high mobility of the interphase boundaries. In this regard, the proposed method for predicting the type of emulsions of polymers, taking into account the contact wetting angle and the wetting area of the surface of solid particles of a stabilizer with water and a polymer, requires further verification on various systems. The obtained data of fundamental importance also allowed us to propose new applications of stabilized concentrated artificial latexes for solving applied problems.

Studies of the Effect of Decontamination Methods on the Surface Condition of the Stoppers in Contact with Drugs

The influence of means and modes of sanitary-hygienic treatments on the surface condition of medical rubber stoppers based on butyl and halobutyl rubbers used for sealing injection and infusion drugs was investigated using the method of determining the contact wetting angle on a DCAT 21 tensiometer. It has been established that the methods used for sanitary-hygienic processing have a destructive effect on the state of the surface, accompanied by a decrease in the edge angle of wetting (an increase in the hydrophilicity of the surface of the stoppers), which significantly increases the possibility of interaction with the dissolved pharmaceutical substances of drugs.

Changing the Contact Wetting Angles when Adding Surface-Active Substances to Washing Solutions

Introduction. The technological processes of the washing contaminations are largely determined by the nature of the surface being cleaned, the contamination type and the environment, in which the cleaning is carried out. The efficiency of the process depends on the contact of the detergent with the surface being washed. The wetting characteristic is a contact angle, which is a measure of the relative attraction of a liquid to a solid and to liquid itself. The physico-chemical activity of the washing medium determines the costs and, consequently, the optimal parameters of the washing process. In addition, it affects the increase in corrosion resistance. Therefore, it is relevant to determine the functional dependence of the contact wetting angle on the concentration of various combinations of surfactants. Materials and Methods.The determination of the contact wetting angle is based on the statistical processing of a photograph of a detergent drop on a horizontal surface by a specially created program that allows obtaining an array of data to describe the shape of a drop from which the contact wetting angle is calculated. The values of the contact wetting angle were measured when varying concentrations of such synthetic detergents as Labomid-203, MS-8, ML-51, etc. Multiplicative power functions connecting the magnitude of the contact wetting angle with surfactant concentrations were obtained. Results. The studies has shown that an increase in the concentration of potassium monoborate with Labomid-203 by 1 % leads to a decrease in the contact wetting angle by 0.54 %; potassium monoborate with MS-8 by 0.78 %; and potassium monoborate with ML-51 by 0.48 %, the function shows a decreasing return to an increase in concentration. Discussion and Conclusion. In all the considered cases, a decreasing return of the magnitude of the contact wetting angle to an increase in the concentration of surfactants was established, regardless of which combination of substances was used. That is, the investigated concentrations of surfactants exceeded the limit value when they gave an increasing return to the increase in their content in the washing solution. Thus, it can be concluded that for the considered combinations the percentage of surfactant is redundant.

Tool wear in dry turning and wet turning with non-toxic cutting fluid

PurposeThis study aims to determine the properties of a new non-toxic cutting fluid and compared with cutting fluid based on mineral oil.Design/methodology/approachThe tool wear was measured under dry and wet cutting conditions. The non-toxic cutting fluid was compared with cutting fluid based on mineral oil. The experiments were carried out using CTX 310 ECO numerical control lathe. The wear of the cutting tools was measured by means of stereo zoom microscopy (SX80), while the elements were identified through scanning electron microscopy (JSM 7100F). The workpiece surface texture was studied using a Talysurf CCI Lite non-contact 3D profiler. The contact wetting angle was established with a KSV CAM 100 tester.FindingsThe non-toxic cutting fluid has reached comparable coefficient of friction with a coolant containing mineral oil. The use of the non-toxic cutting fluid with low foaming tendency resulted in lower wear.Practical implicationsMachining processes require that cutting fluids be applied to reduce the tool wear and improve the quality of the workpiece surface. Cutting fluids serve numerous purposes such as they act as coolants and lubricants, remove chips and temporarily prevent corrosion of the product.Originality/valueThe investigations discussed in this paper have contributed to the development of non-toxic and environmentally friendly manufacturing because of the use of cutting fluid containing zinc aspartate and its comparison with commonly used cutting fluid.