Swelling Process Research Articles

Statistical analysis of the swelling process of casein microparticles based on single particle measurements

Film drying is used for the gentle production of casein microparticles. These result from aggregates that have previously formed in solution from micellar caseins in the presence of pectin under neutral pH conditions. The particles are stabilized by hydrophobic interactions and have a spherical shape. Their swelling behavior, which is enhanced with increasing pH, could be of interest for future applications in the field of drug encapsulation and release. The swelling of the microparticles occurs within minutes at pH 11, making it possible to perform a total of 46 consecutive individual tests. The analysis of the results showed that the microparticles keep their spherical shape during swelling. Furthermore, the swelling process proceeds in two steps, the rates of which are independent of the initial size of the casein microparticles. The values of the five parameters of the dynamic swelling model, which is used for the analysis of the kinetics, are examined with the Bravais-Pearson coefficient for pairwise linear correlations. Both swelling steps can be clearly distinguished with regard to rate and characteristic time, whereby the second swelling step at pH 11 consequently has a larger characteristic initial time but also a larger rate. For the first swelling step, the characteristic time and the rate coefficient are uncorrelated, while the rate for swelling step 2, which ends with the disintegration of the casein microparticles, is smaller the later it begins. Since there is a positive correlation between the characteristic times of the two swelling steps, it can be concluded that those particles are most stable for which the swelling process starts the latest. It seems plausible that a different degree of hydration of the microparticles after preparation is the cause of the observed stability differences.

Automated research of the process of the swelling of sealings of draining devices in the tank railcars

Automated research of the process of the swelling of sealings of draining devices in the tank railcars

Comparative study of dye adsorption onto CNT/PVDF and reduced rGO/PVDF membranes post-treated by a swelling and freeze-drying process

Comparative study of dye adsorption onto CNT/PVDF and reduced rGO/PVDF membranes post-treated by a swelling and freeze-drying process

Gas Formation Reactions in the Raw Mixture Based on TPP Ash

The article discusses the physicochemical mechanisms of the effect of chemical reagents on the processes of swelling of the raw mixture based on the ash of thermal power plants. The process of structure formation in such mixtures occurs as a result of physicochemical transformations of its constituent components. To intensify gas evolution and obtain materials of a porous structure, the presence of a gas former is necessary. The author has analysed the possibility of creating a porous structure in a raw mixture based on ash with the introduction of various gas formers or their formation as a result of exchange reactions. The main chemical compounds contributing to pore formation have been determined. To form a given structure, it is proposed to control chemical transformations at the stage of swelling. To study the processes of intensification of gas evolution, the author proposes to investigate the mechanisms of the influence of mineral fillers and chemical reagents on swelling processes based on the analysis of the Gibbs equation. The parameters of the Gibbs equation are obtained, by which it is possible to determine the probability of the occurrence of chemical reactions with the proposed chemical agents for the formation of gas bubbles with (pores) in the raw material.

Synergic Effects of Surfactant and Chelating Agent on Stubborn Keratin Grime for Easy Cleaning.

We report on the synergic effect of surfactants and chelating agents on the mechanism to remove stubborn keratin grime (keratin-Ca), which is bound with calcium ions and one of the most difficult grimes to remove, in order to make it easier to clean bathtubs in less time and with less scrubbing. Our approach was to focus on keratin swelling, which we achieved by applying aqueous solutions with chelating agents and anionic surfactants, the combination of which greatly improved the swelling ratio, resulting in quick, easy removal of keratin-Ca with water rinsing and little scrubbing. For the swelling process, we added chelating agents and anionic surfactants to swell the keratin-Ca by both capturing calcium ions and improving solution permeation. Furthermore, we measured the structural change of the keratin-Ca during swelling by TD-NMR and confirmed that a certain combination of chelating agent and anionic surfactant improved swelling by affecting not only the amorphous part such as the keratin matrix, but also the crystalline part such as the intermediate filaments (IFs).

Die shape optimization for extrudate swells using feedback control

In this paper we propose a completely unique approach to unravel the inverse problem of three-dimensional die design forextrudate swell, employing a real-time active control scheme. to the present end, we envisioned a feedback connectionbetween the corner-line finite element method, wont to predict the positions of the free surfaces of theextrudate, and therefore the controller. The corner-line method allows for local mesh refinement and transient flow tobe taken under consideration. We show the validity of this method by showing optimizationresults for 2D axisymmetric extrusion flows of a viscoelastic fluid for various Weissenberg numbers. In 3D wefirst provides a proof of concept by showing the results of a Newtonian fluid exiting dies with increasing complexityin shape. Finally, we show that this method is in a position to get the specified extrudate shape of extrudates of aviscoelastic fluid for various Weissenberg numbers and different amounts of shear-thinning.extrusion may be a common production technique within the polymer pro-cessing industry to get products with a desired cross-section. Inthis process a polymer is molten and pushed through a die with acertain cross-sectional shape, to get a product (extrudate) with thissame cross-sectional shape. a standard requirement on the extrudate isdimensional precision. However, the size of the extrudate arehighly influenced by a phenomenon called extrudate swell, where theextrudate starts to expand thanks to internal stresses within the polymer onceit leaves the die.The swelling process involves complex dynamics influenced bymany parameters like viscoelasticity and temperature.

Water absorption dependence of the formation of poly(vinyl alcohol)-iodine complexes for poly(vinyl alcohol) films.

Poly(vinyl alcohol) (PVA) films annealed at different temperatures are used to explore the effects of the water absorption on the formation of PVA–iodine complexes. It's found that the higher the annealing temperature, the stronger the interaction force between PVA segments, and the smaller the free volume of the PVA films. These mainly lead to the reduction of the amount of PVA segments with a moderate degree of hydration (i.e., PVA segments with moderate mobility), which are the major segments participating in the formation of PVA–iodine complexes. Therefore, PVA films with higher water absorption not only possess faster complexation speed and form more PVA–iodine complexes, but also increase the proportion of polyiodide ions with a longer length. Moreover, the complexation restricts the PVA segments with high mobility, resulting in the formation of the intermolecular ordered structure. The water absorption dependence may guide the dyeing process to obtain PVA polarizers with excellent optical performance.

Design of weakly cationic alco-cryogels consisting of poly(alkylmethacrylates)-based sulfonated terpolymer network with tunable multiresponsive assembly

Cryogels with ion-, and solvent-responsiveness have been designed by cryogelation of 2-(diethylamino)ethyl methacrylate (DEAEMA) as weakly cationic monomer, hydroxyethyl methacrylate as neutral comonomer and 2-acrylamido-2-methyl-1-propanesulfonic acid as anionic termonomer in ethanol-water mixture (50:50 v/v), which had been proved to offer a good miscibility of monomers. Influence of composition of terpolymer and polymerization temperature on the properties of terpolymer cryogels (Cgels) and hydrogels (Hgels) were evaluated by swelling kinetics, and response against rapid ionic strength change. Degree of swelling was extremely sensitive to salt concentration, cation/counterion type as well as the solvent type; acetone and monohydric alcohols with various hydrophobic alkyl groups; methanol, ethanol, and 2-propanol. Swelling of terpolymer networks in the form of Cgel and Hgel decreased with increase in the size of ions present in swelling medium and followed the order of swelling behavior Cl− > Br− > I−. Terpolymer alcogels exhibited salting-out behavior in the presence of Cl− and Br− ions, while “salting-in” behavior was observed in KI solutions of high concentrations. Sensitivity sequence of terpolymer alcogels to mono- and di-valent cations with a common anion (SO42−) on swelling was Na⁺ > K⁺ > Mg2⁺> Zn2+. Variation of elastic moduli with swelling in salt solutions was investigated and for terpolymer hydrogels, possible contribution of ionic crosslinks to effective crosslinking density νe was discussed. Increasing Na2SO4 concentration up to 0.1 M induced a 2-fold increase in the elastic modulus of terpolymer alcogels. With attention to the polarity of solvent, terpolymer gels exhibited an irregular swelling profile with a change in composition of solvent, showing the so called cosolvency phenomena. After two successive cycles of swelling and shrinking promoted by the change of ionic strength of KCl solution, the terpolymer gels were stable and dynamic swelling process was reversible. Swelling data agree well with second-order kinetic model and with increasing amount of DEAEMA in terpolymer feed, diffusion mechanism changed from non-Fickian type to Fickian diffusion. In ionic environments, the salt-sensitivity and excellent water absorption/retention capability give this intelligentized terpolymer gels wide potential applications.

Evaluation of the fractal dimension of polyacrylamide during gelation and swelling

The photon scattering method was performed to monitor the free radical crosslinking copolymerization (FCC) of acrylamide (AAm) applied with N,N′-methylenebis (acrylamide) (Bis) in time. FCC experiments were conducted using different Bis contents to create fractal-like network structures in polyacrylamide (PAAm) gels. Higher intensity values of the scattered photons, Isc were observed with increasing Bis content, BC, at a given time, which was attributed to fractal-like macrogel formation from interconnected microgels. The same gels were used in swelling experiments after drying, and increased Isc intensities from the PAAm gels were observed during the swelling process. Fractal dimensions, d during the gelation and swelling processes were measured and found to be increased as gelation and swelling times increased. According to the results obtained from the gelation measurements, it was seen that the fractal size, d, increased from very small values to 3.00. A similar increase in the range 1.00–1.66 was observed during swelling experiments.

The current state and tendencies of using rheological models for self-forming wooden structures

Wood is a natural and ecological material. Exceptional mechanical properties of wood allow it to be used in building structures subject to chemically active substances. However some changes in mechanical characteristics of wood under the influence of water and temperature, as well as its anisotropy, limit the application areas of this material. Based on the results of the research by S.P. Timoshenko, foreign scientists proposed a method that makes it possible to use these shortcomings of wood to create wooden structures of unique shapes. This article considers the self-forming process of glued layered wooden structures, which is based on various rheological processes taking place in wood. In order to predict the shape of a glued layered wooden structure obtained with the self-forming method, an accurate rheological model is required, which takes into account all wood deformation mechanisms. We analyzed the available rheological models of wood proposed or described both by Russian and foreign scientists, as well as the international experimental studies and numerical modeling results of the self-formed glued layered wooden structures. Based on the analysis results, it was found that the present rheological models do not take into account a number of factors that influence the process of self-forming of glued layered wooden structures. The rheological model, which includes a complete list of factors affecting wood deformation (elastic and plastic deformation, wood shrinkage or swelling, viscous-elastic creep deformation and mechanical and sorption deformation), is the most promising for creating unique architectural objects from glued wood. But it also has a number of shortcomings, mainly due to inconsideration of some factors and few experimental studies. Such factors include the geometric parameters of layers of the glued wooden structures, the surface treatment of layers, temperature, as well as wood species. These factors influence the process of wood shrinkage and swelling, thus the final shape of a wooden structure. It is necessary to have additional experimental and theoretical studies of the mechanical behavior of glued wooden structures which will take into account these factors, as well as to study other species of wood including their combinations.

Nonmonotonic swelling and compression dynamics of hydrogels in polymer solutions.

Hydrogels are sponge-like materials that can absorb or expel significant amounts of water. Swelling up from a dried state, they can swell up more than a hundredfold in volume, with the kinetics and the degree of swelling depending sensitively on the physicochemical properties of both the polymer network and the aqueous solvent. In particular, the presence of dissolved macromolecules in the background liquid can have a significant effect, as the macromolecules can exert an additional external osmotic pressure on the hydrogel material, thereby reducing the degree of swelling. In this paper, we have submerged dry hydrogel particles in polymer solutions containing large and small macromolecules. Interestingly, for swelling in the presence of large macromolecules we observe a concentration-dependent overshoot behavior, where the particle volume first continuously increases toward a maximum, after which it decreases again, reaching a lower, equilibrium value. In the presence of smaller macromolecules we do not observe this intriguing overshoot behavior, but instead observe a rapid growth followed by a slowed-down growth. To account for the observed overshoot behavior, we realize that the macromolecules entering the hydrogel network not only lead to a reduction of the osmotic pressure difference, but their presence within the network also affects the swelling behavior through a modification of the solvent-polymer interactions. In this physical picture of the swelling process, the net amount of volume change should thus depend on the magnitudes of both the reduction in osmotic pressure and the change in effective solvent quality associated with the macromolecules entering the pores of the hydrogel network. We develop a phenomenological model that incorporates both of these effects. Using this model we are able to account for both the swelling and compression kinetics of hydrogels within aqueous polymer solutions, as a function of the size of the dissolved macromolecules and of their effect on the effective solvent quality.

Mathematical Model for Estimating Parameters of Swelling Drug Delivery Devices in a Two-Phase Release.

Various swelling drug delivery devices are promising materials for control drug delivery because of their ability to swell and release entrapped therapeutics, in response to physiological stimuli. Previously, many mathematical models have been developed to predict the mechanism of drug release from a swelling device. However, some of these models do not consider the changes in diffusion behaviour as the device swells. Therefore, we used a two-phase approach to simplify the mathematical model considering the effect of swelling on the diffusion coefficient. We began by defining a moving boundary problem to consider the swelling process. Landau transformation was used for mitigating the moving boundary problem. The transformed problem was analytically solved using the separation of variables method. Further, the analytical solution was extended to include the drug release in two phases where each phase has distinct diffusion coefficient and continuity condition was applied. The newly developed model was validated by the experimental data of bacterial cellulose hydrogels using the LSQCURVEFIT function in MATLAB. The numerical test showed that the new model exhibited notable improvement in curve fitting, and it was observed that the initial effective diffusion coefficient of the swelling device was lower than the later effective diffusion coefficient.

Minimal nutrient requirements for induction of germination of Aspergillus niger conidia

Aspergillus niger reproduces asexually by forming conidia. Here, the minimal nutrient requirements were studied that activate germination of A. niger conidia. To this end, germination was monitored in time using an oCelloScope imager. Data was used as input in an asymmetric model to describe the process of swelling and germ tube formation. The maximum number of spores (Pmax) that were activated to swell and to form germ tubes was 32.54% and 20.51%, respectively, in minimal medium with 50 mM glucose. In contrast, Pmax of swelling and germ tube formation was <1% in water or 50 mM glucose. Combining 50 mM glucose with either NaNO3, KH2PO4, or MgSO4 increased Pmax of swelling and germination up to 15.25% and 5.4%, respectively, while combining glucose with two of these inorganic components further increased these Pmax values up to 25.85% and 10.99%. Next, 10 mM amino acid was combined with a phosphate buffer and MgSO4. High (e.g. proline), intermediate and low (e.g. cysteine) inducing amino acids were distinguished. Together, a combination of an inducing carbon source with either inorganic phosphate, inorganic nitrogen or magnesium sulphate is the minimum requirement for A. niger conidia to germinate.

Antimicrobial Cellulose Nanocomposite Films with In Situ Generations of Bimetallic (Ag and Cu) Nanoparticles Using Vitex negundo Leaves Extract

Antimicrobial cellulose nanocomposite films with in situ synthesized bimetallic nanoparticles were developed by a three-step process. These antimicrobial cellulose nanocomposite films with in situ synthesized bimetallic, silver (Ag) and copper (Cu) nanoparticles (NPs) through the apozem of medicinal important plant Vitex negundo (Vavili) leaves, and which is acts as a bio-reductant and stabilizing agent. Through a three-step process, the cellulose films were prepared via a solution casting method and loaded with the apozem of V. negundo (Vavili) leaves via the swelling process. The resulted nanocomposite films were characterized by XRD, UV, FTIR, SEM/EDAX, TGA, UTM and antibacterial measurements. The XRD studies confirm that the presence of AgNPs and CuNPs in the cellulose matrix. The formation Ag/Cu, bimetallic nanoparticles were observed by the change of the color of the cellulose films. The presence of UV absorption peaks at around ~ 415 (Ag) and ~ 570 nm (Cu) confirms the formation of bimetallic cellulose nanocomposite films. The SEM and EDAX spectrum confirmed the presence of Ag, Cu, and Ag/Cu elements. The average size of the Ag–Cu, Ag, and Cu nanoparticles generated were ~ 60, ~ 67, and ~ 74 nm, respectively. The UTM and TGA studies revealed that bimetallic nanocomposites have high strength and stability than monometallic nanocomposite films. The nanocomposites have shown good antibacterial activities towards gram-positive and gram-negative bacteria. These cellulose nanocomposite films stand as good candidature for food, medical, and disinfection packaging materials.

A fractional viscoplastic model to predict the time-dependent displacement of deeply buried tunnels in swelling rock

This study focused on tunneling under challenging conditions, particularly with regard to the stress distribution and deformation in the humidity stress field. The swelling phenomenon during tunneling was treated as a quasi–humidity–mechanics coupled process, where the humidity diffusion and stress dilatancy were considered together to obtain the stress and deformation fields for tunnels crossing formations with high swelling potential. A solution to the nonstationary process of humidity transfer was derived according to Fick’s second law. First, the humidity distribution was obtained from the surrounding rock mass to determine the stress field. Then, a modified fractional viscoplastic model was developed to describe the whole creep process of soft rock swelling, as well as the damage and swelling deformation due to water immersion. Next, closed-form analytical solutions were derived for the displacement in the viscoplastic region, with more focus on the tunnel wall, based on a non-associated flow rule. The sensitivity of time-independent parameters was also analyzed. The solution was found to reasonably represent the tunnel convergence versus time when compared with the numerical simulation and monitoring data from the Nabetachiyama Tunnel.

Facile Formation of Hierarchical Textures for Flexible, Translucent, and Durable Superhydrophobic Film

AbstractFlexible superhydrophobic surfaces have recently attracted extensive interest not only in the field of burgeoning flexible electronics, but also for the practicability toward various situations. Herein, a cost‐effective and environment‐friendly approach is demonstrated to realize the durable, flexible, and superhydrophobic film with optical transparency. Without sophisticated facilities, the essential hierarchical architecture to render a low‐adhesive surface is achieved via magnetic field‐assisted polydimethylsiloxane microcilia, followed with the swelling process to decorate nanoscaled particles with excellent robustness. This tight connection between the microcilia and decorated nanoparticles renders the mechanical robustness with resistance to ultrasonic treatment, sandpaper abrasion, and high‐speed water impact. The film further exhibits outstanding stabilities when exposed to organic contamination, hot water, and chemical corrosions. Water repellency is well preserved when the film is under various mechanical deformations including cyclic stretching, bending, and squeezing. For practical demonstrations, the film is applied as the protective film for touch screen owing to the intrinsic optical transmittance, or serves as the water‐proof covers for sorts of complex/curved surfaces. These stated features reveal the convincing potential of the methodology to be applied for the circumstances where simultaneous addressing of robustness, flexibility, and adaptability is highly appreciated.

Quantitative study of starch swelling capacity during gelatinization with an efficient automatic segmentation methodology

A novel image segmentation methodology combined with optical microscopy observation was developed for qualifying starch swelling. Starch granules in the micrograph were successfully segmented based on high-precision edges extraction achieved by Canny edge detection together with mathematical morphology operation. Granules were automatically identified by computer vision and characterized by giving quantifiable area of these granules. The evolved swelling process could be generally divided into two phases. During the first phase, starch granules were only swollen up by 2.56 %, which is hard to be identified by conventional naked eye. During the following narrow temperature interval (60–66 ℃), these starch granules were detected to swell up significantly by 9.08 %. Through the granule area variable, swelling capacity was high-throughput characterized, which allows for the whole evaluation to be completed within a couple of minutes. The proposed methodology showed a high accuracy and potential as a novel technique for characterizing gelatinization.

A multi-tool structural change investigation of Indian vitrinite rich bituminous coal due to CS2/NMP interaction

Solvents are important constituent in the coal liquefaction process as they act as hydrogen donors and serve as hydrogen shuttles between hydrogen and coal. A mixture of carbon disulfide (CS2) and N- methyl-2-pyrrolidinone (NMP) (1:1, v/v) was used as a solvent for a study of an Indian coal that was kept for swelling. The study of coal swelling provides valuable information, such as, determining the highest energy bond that can be broken by a particular solvent or by a mixture of solvents. It can be concluded from the results that maximum swelling and extraction yield are achieved by a CS2/NMP mixed solvent. The structure change of coal before and after its interaction with the solvent was also studied using techniques such as Fourier-transform infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HRTEM), and X-ray powder diffraction (XRD). FTIR indicated that the mixed solvent caused a decrease in the solvent viscosity, enabling the solvent to penetrate more quickly into the coal structure. XRD structural parameters concluded a decrease in aromaticity and stacking height and an increase in the interplanar spacing of raw coal after the swelling process. This was due to a decrease in the crystalline carbon along with an increase in amorphous carbon. XRD results indicated that the four parallelogram-shaped aromatic sheets were parallelly connected. This was also clearly observed in HRTEM images. This work will be helpful in the understanding and development of coal liquefaction technology.

Improved Computational Fluid Dynamics Framework for Reactor Core Baffle Swelling Assessment

Abstract This paper presents an improved estimation of reactor core baffle temperature distribution, during operation, at the nominal power level to address swelling problems of the reactor internals. Swelling is the main limiting factor in the reactor core internals long term operation of VVER-1000 nuclear units. The material irradiation-induced swelling and creep models are very sensitive to temperature distribution in metal; thus, a more detailed analysis of the core baffle metal thermohydraulic cooling characteristics is required. A framework for the computational fluid dynamics (CFD) analysis of VVER-1000 reactor baffle cooling is presented. First, an analytical model was developed to obtain boundary conditions (BCs) and simplify CFD analysis. Second, the CFD analysis was performed using 60 deg symmetry, which included core, baffle, and core barrel, and it is limited by the height of the baffle. Core is simplified as an equivalent coolant domain with considering of spatial volumetric energy release. Core baffle is presented as monolithic body with considering of gamma-ray heat generation. Model includes cooling ribs and simplified geometry of connecting studs, with cooling flow of the coolant through the nuts grooves. Calculated convection coefficient and temperature are in good agreement with analytical model and give a more accurate result comparing to RELAP5/mod3.2. Obtained temperature field was used to estimate baffle swelling process and justify safe long term operation of the reactor internals.

Two-Dimensional Molecular Sheets of Transition Metal Oxides toward Wearable Energy Storage.

Flexible and wearable electronics have recently sparked intense interest in both academia and industry because they can greatly revolutionize human lives by impacting every aspect of our daily routine. Therefore, developing compatible energy storage devices has become one of the most important research frontiers in this field. Particularly, the development of flexible electrodes is of great significance when considering their essential role in the performance of these devices. Although there is no doubt that transition metal oxide nanomaterials are suitable for providing electrochemical energy storage, individual oxides generally cannot be developed into freestanding electrodes because of their intrinsically low mechanical strength.Two-dimensional sheets with genuine unilamellar thickness are perfect units for the assembly of freestanding and mechanically flexible devices, as they have the advantages of low thickness and good flexibility. Therefore, the development of metal oxide materials into a two-dimensional sheet morphology analogous to graphene is expected to solve the above-mentioned problems. In this Account, we summarize the recent progress on two-dimensional molecular sheets of transition metal oxides for wearable energy storage applications. We start with our understanding of the principle of producing two-dimensional metal oxides from their bulk-layered counterparts. The unique layered structure of the precursors inspired the exploration of their interlayer chemistry, which helps us to understand the processes of swelling and delamination. Rational methods for tuning the chemical composition, size/thickness, and surface chemistry of the obtained nanosheets and how physicochemical properties of the nanosheets can be modulated are then briefly introduced. Subsequently, the orientational alignment of the anisotropic sheets and the origins of their liquid-crystalline characteristics are discussed, which are of vital importance for their subsequent macroscopic assembly. Finally, macroscopic electrodes with geometric diversity ranging from one-dimensional macroscopic fibers to two-dimensional films/papers and three-dimensional monolithic foams are summarized. The intrinsically low mechanical stiffness of metal oxide sheets can be effectively overcome by wisely designing the assembly mode and sheet interfaces to obtain decent mechanical properties integrated with superior electrochemical performance, thereby providing critical advantages for the fabrication of wearable energy storage devices.We expect that this Account will stimulate further efforts toward fundamental research on interface engineering in metal oxide sheet assembly and facilitate wide applications of their designed assemblies in future new-concept energy conversion devices and beyond. In the foreseeable future, we believe that there will be a big explosion in the application of transition metal oxide sheets in flexible electronics.