Kinetics Of Impregnation Research Articles

Carbon black/electrolyte interface study by electromagnetic and electrochemical techniques in γAl2O3/poly(vinylidene fluoride)/carbon black composite materials: Application for lithium-ion batteries

This work aims at better understanding the interactions existing between the liquid electrolyte and the solid composite electrode in a Li-ion battery. We substituted the common active material (e.g. LiNi1/3Mn1/3Co1/3O2 or LiFePO4) by an insulating (inactive) γ-Al2O3 compound in order to detect and evidence the interaction between the carbon black electronic additive and the liquid electrolyte. Our study presents the characterization of charge (electrons and ions) transport at different scales by combining a high-frequency analysis performed by broadband dielectric spectroscopy (BDS, up to 1010 Hz), along with a low-frequency analysis performed by electrochemical impedance spectroscopy (EIS, down to 10−3 Hz). Two carbon black materials with two different specific surface areas (80 m2.g−1 and 65 m2.g−1, respectively) were studied. The electronic percolation threshold and the kinetics of impregnation of the hierarchical composite electrode by the liquid electrolyte have been determined with respect to the carbon black content. The significant influence of the adsorbtion of ions at the carbon black surface on the electrons transport is particularly highlighted and explained.

Вивчення змочування та кінетики просочення оксидних волокон розплавами свинцю та його сплавів

The effect of metal coverings on wetting of oxide fibers by lead, bismuth, tin-lead-bismuth-cadmium alloy in vacuum 2·10-3 Pa in the temperature range 400–600 oC was studied by the sessile drop method using the capillary purification method of melt. Oxide fibers plaits that have been placed on a silicon oxide substrate as wetting substrates used. Titanium and nickel powders were used as metal coatings. There is no wetting. The contact angles are close to or greater than 90 degrees and only in the case of the lead-titanium melt system at 600 oC the value of the angle is 15, respectively. The use of a dropper allows separate heating of the melt and the substrate, capillary and thermo vacuum cleaning of the melt, as well as thermo vacuum cleaning of the coatings surface. This is a model scheme of the impregnation process of non-metallic frames with matrix melts in the manufacture of composite materials by spontaneous free impregnation. The metal titanium, nickel powder coatings for the method of spon¬taneous free impregnation was used. The study of the kinetics of impregnation of plaits of oxide fibers with melts of lead and tin-lead-bismuth-cadmium alloy was performed at 600–700 oC. The metal melt impregnates metal powders well. The rate of impregnation is quite high 1,1–1,8 mm/s. The obtained results allow the use of titanium pastes for the manufacture of composites from oxide materials with lead matrices. Composites were made. Oxide fiberglass made of CRT waste was selected as the reinforcing material. Lead was chosen as the matrix metal. Despite the fact that lead is a harmful material, but its use as a matrix phase for composites from the action of ionizing radiation is indispensable. Keywords: spontaneous free impregnation, composites, lead melts, oxide fibers, wetting, metal coverings.

Impregnation of Woven Fabrics from Chemical Yarns during Formation of Composite Textile Materials

A composite textile material is a material consisting of two or more components formed by textile technologies into a unified structure with physicomechanical properties that differ from the properties of the components. Theoretical and experimental investigations were carried out, and a complex mathematical model was developed for the kinetics of impregnation of textile materials with aqueous dispersions and solutions of polymeric binders with various compositions. This made it possible to determine rational regimes for the formation of composite textile materials in relation to their geometric characteristics and also to the physicochemical characteristics of the binder.

Improving impregnation techniques for fine coniferous and non-coniferous wood

Wood modification with the improvement of its physical and mechanical properties is a promising way to increase the commercial quality of the material and enhance its sustainable use. This article presents the results on developing a model for impregnation with water of fine coniferous and non-coniferous wood by centrifugal processing techniques. The mathematical modeling is based on Darcy's law. According to the model representation, the impregnation rate of the wood specimenis proportional to the pressure ratio of the impregnation liquid. The proportionality factor is a constant value that depends on the. Performed comparative analysis revealed the perfect consistency of calculations made using the formula of a centrifugal model with the experimental data. According to the analysis of impregnation rate time dependencies, the main saturation of the treated sample with liquid (70%) occurs in 1/3 of the complete cycle time. Besides, the established model allows determining with high accuracy the impregnation time as a function of atmospheric pressure, rotational speed, and the ratio of woodsample length to centrifuge platform radius for different wood species. Further studies are planned on evaluating the effect of different liquids viscosity on the kinetics of wood impregnation as well as determining the applicability of the proposed model.

Kinetics of Vacuum Impregnation of Parallelepipeds of Cidra (Sechium edule (Jacq.) Swartz) with Mora and Grape Formulations

La cidra Sechium edule (Jacq.) Sw., se encuentra entre los alimentos con bajo contenido de grasa y alto contenido en fibra, vitaminas y minerales y puede ser utilizada como vehículo para la adición de compuestos bioactivos. El proceso de impregnación a vacío (IV) se utiliza como alternativa para la conservación y adición de compuestos bioactivos y solutos, mejorando las características nutricionales y sensoriales, para realizar este proceso se utilizaron los frutos de mora y uva por su atractivo color, jugosidad, sabor agradable y alto contenido de vitaminas, minerales y compuestos fenólicos. El objetivo de esta investigación fue determinar la cinética de impregnación a vacío de paralelepípedos de cidra en formulaciones de mora y uva. Se prepararon cinco formulaciones % v/v con pulpa de mora y uva (A:100% mora, B:100% uva, C: 25% mora/75% uva, D:50% mora/50%uva, E:75% uva/25% mora), la cidra se troceó en geometría de paralelepípedos y se sumergieron en las formulaciones para realizar la IV aplicando un pulso de vacío de 50 mbar los primeros 5 min seguido de restauración de la presión atmosférica durante 5 min; este procedimiento se repitió hasta alcanzar peso constante. Las muestras de cidra alcanzaron el equilibrado entre 100 y 120 min de tratamiento. La formulación D fue la que mejor respondió a este sistema de presiones, ya que los paralelepípedos presentaron menor pérdida de peso lo que indica mayor ganancia de solutos.

Kinematic characterization of the pressure-dependent PCM impregnation process for radiata pine wood samples

This paper reports on the properties of Pinus radiata wood impregnated with an organic phase change material (O-PCM). The tests are aimed at characterizing the kinetics of impregnation (rates, flows, and fronts) and the thermophysical properties (thermal conductivity and specific heat). In particular, a paraffin type O-PCM (octadecane) is used to impregnate dry radiata pine wood in the tangential flow direction at four manometric pressures (0, 1, 2, and 3 bar) and constant temperature of 50 °C. The wood is sapwood from 12-year old P. radiata growing in the Bio-Bio region and dimensioned according to Chilean standard for treated wood sample extraction. The results show that it is viable to impregnate P. radiata wood with O-PCM to improve its thermophysical properties with the purpose of passive conditioning.

A study of the effect of network angle of fabrics on kinetics of impregnation upon molding of articles made from carbon plastics

The permittivity coefficient, volume, and porosity of an elementary cell of fabric filler have been calculated. Two types of fabric structures have been considered using the example of carbon fabric: standard, in which filament yarn is cylindrical, and spread, it which it has a rectangular shape. A reflector of a mirror space antenna has been considered characterized by the presence of doubly curved surfaces is used as the object of study. Modeling of the kinetics of impregnation of reflector for two types of fabric structures has been carried out using the RAM–RTM program. In the work, the effect of the network angle on the duration of impregnation process has also been investigated. Based on the results of calculation, reflector samples have been made and their quality has been evaluated. Theoretical and experimental results have been compared.

Kinetics of fiber impregnation by a binder. Gradient generalization of Navier–Stokes–Darcy equations

A model of polymer composition material that is composed of a unidirectional fiber and binder has been considered. The space between two neighboring filaments of fibers is considered as a capillary along which the binder propagates during impregnation. In order to describe the flow process, a gradient generalization of the Navier–Stokes equation has been suggested. A corrected model of the flow of binder in the capillary-porous space of a unidirectional fiber material is developed on its basis. In particular cases, the found solution coincides with the Navier–Stokes–Darcy equations and conventional Navier–Stokes equation. The model that has been developed allows the refinement of the nonclassical effect of the existence of two boundary layers that appear during flow and may prevent it.

In situ investigation of supercritical CO2 assisted impregnation of drugs into a polymer by high pressure FTIR micro-spectroscopy.

An original experimental set-up combining a FTIR micro-spectrometer with a high pressure cell has been built in order to analyze in situ the impregnation of a solute into microscopic polymer samples, such as fibers or films, subjected to supercritical CO2. Thanks to this experimental set-up, key factors governing the impregnation process can be simultaneously followed such as the swelling of the polymeric matrix, the CO2 sorption, the kinetics of impregnation and the drug loading into the matrix. Moreover, the solute/polymer interactions and the speciation of the solute can be analyzed. We have monitored in situ the impregnation of aspirin and ketoprofen into PEO (Polyethylene Oxide) platelets at T = 40 °C and P = 5; 10 and 15 MPa. The kinetics of impregnation of aspirin was quicker than the one of ketoprofen and the final drug loading was also higher in the case of aspirin. Whereas the CO2 sorption and the PEO swelling remain constant when PEO is just subjected to CO2 under isobaric conditions, we noticed that both parameters can increase while the drug impregnates PEO. Coupling these results with DSC measurements, we underlined the plasticizing effect of the drug that also leads to a decrease in the crystallinity of PEO in situ thus favoring the sorption of CO2 molecules into the matrix and the swelling of the matrix. The plasticizing effect increases with the drug loading. Finally, the speciation of drugs was investigated considering the shift of the carboxyl bands of the drugs. Both drugs were found to be mainly homogeneously dispersed into PEO.

Electroimpregnation of yarns and fabrics with nonwetting liquids

From the engineering point of view, it is attractive to finish fibers and fibrous materials with water-based solutions. However, coating or impregnation of hydrophobic fibrous materials with these liquids is difficult to achieve. In this paper, we consider electrowetting phenomenon as a promising method to fill the materials with nonwetting liquids. Theoretical models demonstrate the effect of applied electric field on impregnation efficiency. Planar fibrous sheets and yarns with interlaced wires are theoretically considered as examples of typical fibrous materials. We estimate the electric field needed to pull the liquid into the pores. Kinetics of forced impregnation into yarns is shown to be faster as compared to planar materials.

Influence of Heat and Mass Transfer on Wood Impregnation Kinetics

We have further developed the nonstationary mathematical model of two‐phase filtration in an anisotropic porous medium — wood — by a fluid, taking into account the temperature dependence of its viscosity. The results of the calculations of the temperature and kinetics of wood impregnation under the action of vacuum and excess pressure for the problem of internal and external heat transfer are presented. The process of preservative impregnation of woodworks with a water‐oil emulsion for various degrees of filling of the autoclave, including the maximum one, has been simulated.

Modeling of the Nonisothermal Impregnation of Wood and Other Porous Media by Fluids

A mathematical model and results of the calculations of the kinetics of impregnation of porous materials by a fluid, whose viscosity essentially depends on temperature, are given. Modeling of the technological process of protective treatment of wooden articles is carried out using, as an example, the impregnation of wood under pressure by a water‐oil antiseptic emulsion heated to 40°C. The efficiency of different methods of deep impregnation is analyzed in the context of both the absorption of a protective substance and the uniformity of its distribution in wood.

Impregnation of Compressible Fiber Mats with a Thermoplastic Resin. Part II: Experiments

The impregnation of compressible glass fiber mats by a thermoplastic resin in the transverse direction is investigated with application to the Glass Mat reinforced Thermoplastics (GMT) lamination process in a double belt press. Amodel proposed in Part I to simulate the kinetics of impregnation and the evolution of the fiber volume fraction profile as the resin front progresses across the fiber mat, as well as after macro-impregnation is complete, is further developed to include micro-impregnation effects. The predictions are compared with experimental results obtained using model systems such as polyethylene glycol and glass fiber mats, as well as an industrially relevant system consisting of polypropylene and glass fiber mats used in the production of GMT blanks. It is shown that significant compression of the fiber mat may occur during impregnation, with subsequent relaxation on a much longer time-scale. Also, fiber bundle impregnation generally occurs after macro-impregnation is complete, the driving force being the local pressure in the resin around the bundles, dictated by the local state of compression of the mat. The model is then used to provide guidelines for optimization of the preform impregnation conditions for a given material configuration.

Impregnation of Compressible Fiber Mats with a Thermoplastic Resin. Part I: Theory

In many cases of composite processing by liquid matrix impregnation, the fiber reinforcement is compressed when it comes in contact with the liquid and then relaxes as the matrix flows within its pores. This phenomenon can be analyzed in terms of local fluid flow, mass conservation and mechanical equilibrium. A model is proposed to simulate the kinetics of impregnation, and the evolution of the fiber volume fraction profile as the resin front progresses, as well as after the front has reached the end of the mold. The analysis is then applied to the case of infiltration of needled glass fiber preforms by a polypropylene matrix, used in the production of Glass Mat Thermoplastic blanks. Aquantification of the effects of applied pressure and fluid viscosity on total process time is provided. It is shown that the time for preform relaxation after the fluid has filled the preform may be much larger than that for impregnation. As a result, an apparently well impregnated part may exhibit an inhomogeneous distribution of the reinforcement, in turn inducing a modification of the mechanical behavior and residual stress distribution.

Impregnation of Compressible Fiber Mats with a Thermoplastic Resin. Part II: Experiments

The impregnation of compressible glass fiber mats by a thermoplastic resin in the transverse direction is investigated with application to the Glass Mat reinforced Thermoplastics (GMT) lamination process in a double belt press. Amodel proposed in Part I to simulate the kinetics of impregnation and the evolution of the fiber volume fraction profile as the resin front progresses across the fiber mat, as well as after macro-impregnation is complete, is further developed to include micro-impregnation effects. The predictions are compared with experimental results obtained using model systems such as polyethylene glycol and glass fiber mats, as well as an industrially relevant system consisting of polypropylene and glass fiber mats used in the production of GMT blanks. It is shown that significant compression of the fiber mat may occur during impregnation, with subsequent relaxation on a much longer time-scale. Also, fiber bundle impregnation generally occurs after macro-impregnation is complete, the driving force being the local pressure in the resin around the bundles, dictated by the local state of compression of the mat. The model is then used to provide guidelines for optimization of the preform impregnation conditions for a given material configuration.

Modeling of impregnation of wood with protective solutions and emulsions

A calculational model for the process of deep impregnation of wood with solutions and water‐polymer emulsions is developed that takes account of the motion of the fluid, the polymer particles, and the air in the porous structure. Calculated results for the kinetics of impregnation of wood under the action of a pressure gradient and the distribution of the fluid in the material volume are presented. A comparison with experimental data for dry and wet wood is performed.

Kinetics of the wood impregnation process. Modeling and experiment

A physical and mathematical model of deep impregnation of wood by a fluid which allows for motion of the fluid and air in its porous structure is developed. The results of calculations of the kinetics of pressure-gradient impregnation of wood are reported. An experimental impregnation bench intended for investigations of different impregnation conditions and for measurements aimed at refinement of the impregnation parameters is described.

Effect of the binder on the capillary properties of nonwoven materials

The nature and linear density of the fibre, nature of the polymer latex, and composition of the impregnating compound affect the capillary properties of nonwoven cloth impregnated with polymer dispersions. Incorporation of modifying additives on the surface of the fibre or in the impregnating compound significantly alters the kinetics of impregnation of the cloth. The most hydrophobic effect is attained in incorporating the organosilicon product ETS-40 in the compound in the amount of 0.3 wt. %.

Preparation and Evaluation of Skeletal Cobalt-Molybdenum Hydrodesulfurization Catalysts

Preparation of skeletal Co-Mo catalysts by controlled impregnation of aluminosilicate skeletons containing deposited gamma-alumina with aqueous solutions of active component precursors has been investigated. The activity of the laboratory catalysts in gas oil hydrodesulfurization has been determined. Kinetics of impregnation of skeletal supports, the effect of their type, and the dependence of catalyst activity on the content of cobalt and molybdenum sulfides are reported. HDS skeletal catalysts prepared were compared with the extruded types. It was found that skeletal HDS catalysts show the higher activity (related to the content of alumina and Co-Mo sulfides) than the extruded ones due to the less significant effect of internal diffusion. However, if the activity is related to the same volume of catalyst bed, the activity of skeletal catalysts is only one fourth of that of the extruded types.

Estimation of the kinetics of impregnation of fibre materials

An automated method of estimating the kinetics of formation and migration of gas inclusions in fibre materials was developed. The method can be used to estimate the change in the concentration and characteristic dimensions of gas inclusions in materials during impregnation and subsequent drying and polymerization.