Swelling Mechanism Research Articles

Swelling and glyphosate-controlled release behavior of multi-responsive alginate-g-P(NIPAm-co-NDEAm)-based hydrogel

Intelligent controlled release systems (ICRS) displayed great achievement in agriculture by enhancing the utilization efficiency of agrochemicals. In this work, an intelligent graft copolymer (Alg-g-P(NIPAm-co-NDEAm)) with alginate (Alg) backbone and thermo-responsive poly(N-isopropyl acrylamide-co-N,N-diethylacrylamide) (P(NIPAm-co-NDEAm)) side chain was constructed as the matrix of ICRS through redox copolymerization, and its thermo-induced responsive property was studied. Then, the copolymer was mixed with a promising photothermal material semi-coke (SC) to form hydrogel beads (Ca-Alg-g-P(NIPAm-co-NDEAm)/SC) by ion crosslinking. The water absorbency of beads under different stimuli (pH, temperature, and light) presented outstanding responsive performance and the swelling mechanism was analyzed through coupling theory. Furthermore, the release of glyphosate (Gly) from Ca-Alg-g-P(NIPAm-co-NDEAm)/SC under environmental stimuli displayed regulatable behaviors. This multi-responsive hydrogel bead shows bright prospect in the sustainable advancement of crop production.

Preparation, assessment, and swelling study of amphiphilic acrylic acid/chitosan-based semi-interpenetrating hydrogels

The aim of this study was to synthesize amphiphilic semi-IPN hydrogels based on acrylic acid (AA) and chitosan (CS) using AIBN as an initiator and N,N?methylene bis acrylamide as a crosslinking agent. The swelling behavior of the hydrogels was evaluated at a variety of pH values, temperature, the salinity of media and time, and the swelling mechanism was investigated using Fickian diffusion and Schott's 2nd-order-kinetics models. FTIR spectroscopy was used to confirm the synthesis of AA/CS hydrogel. The swelling results showed that, in the acidic media, as the CS content increase the hydrogel swelling ratio reduces. It was found that the maximum swelling ratio (8550%) is attained for the sample HAC2 with an AA/CS ratio of 1:0.001 in the alkaline Ph value. It also revealed that the absorption capacity is directly dependent on the temperature and inversely related to the salt concentration. Besides, the absorption capacity of the synthesized hydrogels in the saline solution of Na2SO4 was higher than NaCl.

Study of Heat-Mass Transfer and Salt-Frost Swelling Mechanism of Sulfate Saline Soil During the Unidirectional Freezing Process

Study of Heat-Mass Transfer and Salt-Frost Swelling Mechanism of Sulfate Saline Soil During the Unidirectional Freezing Process

CO2 and N2 adsorption/desorption effects and thermodynamic characteristics in confined coal

Gas injection into coal seams is gaining increasing attention for improving coalbed methane (CBM) production. This technical development requires detailed and reliable information on gas adsorption/desorption-induced deformation and gas occurrence mechanisms. Hence, in this paper, high volatile bituminous coal was taken as the experiment samples from northern Shannxi Province, China, and adsorption-induced swelling experiments with CO 2 and N 2 were carried out under the conditions of one-time injection and step-by-step injection. Then, based on adsorption-induced swelling characteristics, a thermodynamic model was further established to disclose the adsorption/desorption-induced deformation mechanism of confined coals. Results showed that the swelling/shrinkage strain curves of CO 2 and N 2 adsorption/desorption in the coal matrix were generally divided into four stages, including pressurization-deformation, adsorption-induced swelling, depressurization-deformation, and finally desorption-induced shrinkage. It can be seen that the coal swelling effect caused by N 2 adsorption was far less than that caused by CO 2 adsorption. However, both CO 2 and N 2 adsorption displayed that the apparent volumetric swelling weakened with increasing strain when compared with the same adsorption pressure under different strain conditions. In contrast, the absolute volumetric swelling of the confined coal was a coupling result from adsorption-induced swelling and pore pressure effects. Further, based on the thermodynamic model, it was verified that the adsorbate type, the chemical potential of the adsorbate molecule and stress conditions are key factors affecting adsorption-induced swelling of coal under a certain temperature and pressure. In addition, a desorption lag phenomenon during the desorption-induced shrinkage stage was observed, due to incomplete gas desorption and gas retention in the coal macromolecular network. It was also found that there was a shrinkage phenomenon after the peak strain during gas adsorption. That is to say, when fixed adsorption sites on the coal pore surface reached the adsorption saturation state at the peak strain, gas molecules would be stored in an absorption state in the coal macromolecular network under continuous adsorption. These phenomena further explained coal swelling and gas occurrence mechanisms. • Swelling/shrinkage strain curve can be generally divided into four stages. • Absolute volumetric swelling is controlled by adsorption swelling and pore pressure. • Thermodynamic model reflects Gibbs free energy of gas adsorption in coal decreases. • Adsorption-induced swelling effect tends to be dropped with increasing stress. • Shrinkage effect after peak strain and desorption lag are occurred in whole process.

Impact of the microstructure on the swelling of aluminum alloys: Characterization and modelling bases

Swelling of metals under irradiation is largely studied in the nuclear industry for its impact on the safe and efficient operation of reactors. However, the case of aluminum alloys remains poorly documented as they are exclusively used in nuclear research reactors which operate at lower temperatures than nuclear power plants. Void swelling in aluminum alloys, which results from the cavities induced by the fast neutron flux in reactor, is measurable only at high fluences, for which few measurement points are available. In this study, samples with various quenching rates were used in order to simulate the variations obtainable during the fabrication of large reactor components. A first series of samples were irradiated with heavy ions in single beam (Au 4+ ) to understand the impact of the quenched microstructure on the voids swelling. A second series of samples were irradiated in a triple beam (W 9+ , He + and Si + ) to simulate the aluminum transmutation occurring inside reactors. Samples were investigated at very fine scale and characterized to understand the key mechanisms of swelling. Then, quantitative measurements of the swelling were performed in each sample. A high dispersion of the swelling values and a higher value are observed after ion irradiation compared to neutron irradiation for a similar irradiation dose, which seems to be related to the very high damage rate created by ion-irradiation. Therefore, it appears relevant to complement the description of swelling in aluminum alloys with a modeling approach. Swelling values from the literature were incorporated into a Brailsford & Bullough swelling model for two different damage rates, after estimating the parameters of the model from the literature. This work aims at a better comprehension of the swelling of aluminum alloys both from a quantitative and qualitative point of view and draws the basics requirements for future swelling models.

Preparation, properties, and degradation mechanism of thermosensitive self-degradation microgel

An azo-type thermosensitive crosslinking agent was prepared from azobisisobutyramidine hydrochloride (V-50) and maleic anhydride. It is then copolymerized with acrylamide (AM) and acrylic acid (AA) to prepare thermosensitive self-degradation microgel. The microgel particles are uniformly dispersed in the aqueous solution in the form of particles. Water absorption and swelling experiments of microgel showed that the water absorptivity of microgel decreased with the increase of salinity. And the microgel have the best water absorptivity under a neutral environment. The results of microgel degradation experiments showed that the higher the temperature, the shorter the degradation time, and the degradation is complete within 5 h at 100 °C. The solid residue measured by the degradation liquid is almost 0, indicating that the microgel can be thoroughly degraded at high temperature. The polymer solution after degradation can be measured by gel chromatograph and the average molecular weight is M n=1.9 × 105g/mol. And the swelling and degradation mechanism were summarized.

Fivefold Helical Cellulose Trapped in a Sulfuric Acid Framework

A sulfuric acid aqueous solution effectively dissolves cellulose at a concentration of 64 wt % when it is precooled at −20 °C. Although this low-temperature acid solution has a high potential as an aqueous cellulose solvent, the molecular detail of its swelling and dissolution mechanism is not known. In this study, we followed the swelling behavior of cellulose in sulfuric acid using X-ray diffraction and found a crystalline complex of cellulose and sulfuric acid at −20 °C. In this structure, the sulfuric acid molecules are organized in a similar manner to those in its tetrahydrate crystal. Cellulose molecules adopt a rare fivefold helical conformation, and their hydroxyl groups participate in the hydration of sulfuric acid. This complexation is acid-concentration dependent and occurs only above 62 wt %, indicating that the deficiency of the number of water molecules around sulfuric acid drives the sulfuric acid to recruit cellulose hydroxyl groups to form a stable tetrahydrate-like hydration state. It swells and opens the cellulose structure without completely destroying the crystalline order, as can be confirmed by the partial reversibility to regenerate cellulose I.

Recycling of carbon fiber-reinforced epoxy resin composite via a novel acetic acid swelling technology

Compared with thermal or chemical recycling, the mechanical recycling of the carbon fiber-reinforced polymer (CFRP) is simpler, more economical, and produces less environmental pollution. However, the recycled products of mechanical recycling are only fillers or short fibers with poor reinforcing properties. In this study, acetic acid was used to achieve the full swelling and slight degradation of cured epoxy resin (CEP) in CFRP. The stiff CFRP became soft in the acetic acid medium at 140 °C, and it delaminated into soft single CFRP layers at 160 °C-220 °C within 1 h. Thus, the swollen CFRP can be easily cut into long strips, large thin slices, or other customized shapes. The length and strength of the carbon fibers were preserved well during the reusing process. The shear and delamination products exhibited excellent reinforcing properties, and they can be prepared into new CFRP products through hot pressing. The flexural strength of a newly prepared CFRP board can reach 47%–89% that of the original CFRP board. The swelling and degradation characteristics and mechanism of CEP in acetic acid were also investigated in this study. Thus, this work provides a novel method for recycling thermosetting composites. • Fully swelling of CEP in HAC caused CFRP board became soft and easy processing. • The soft products were cut into long strips and made into CFRP board via hot pressing. • The flexural strength of the re-prepared CFRP can reach 47– 89% of the original CFRP. • The length and strength of the carbon fibers were preserved well by this mild method. • This work provides a novel method for recycling thermosetting composites.

A review on clay chemistry, characterization and shale inhibitors for water-based drilling fluids

Challenges associated with drilling operations are numerous and their adverse effect could lead to severe damage or even shutting down of the drilling operations. Wellbore instability among others is but the most encountered problem by drilling engineers when water-based drilling fluids (WBDF) are applied. This is because shale formations are full of active clay minerals which can lead to hydration and swelling once encountered by the WBDFs thus destabilizing the integrity of the wellbore. To combat this, most petroleum engineers have employed different inhibitors to reduce or stop the menace posed by these active clay minerals. The purpose of this study is to highlight in detail the essential types of clays mostly encountered in drilling operations, the swelling mechanism of the active clay minerals, comprehensive characterization techniques, and the differences associated with the applied inhibitors reported in the literature for tackling clay hydration and swelling. Based on the review, we recommend extensive evaluation between smectite and vermiculite clay minerals during analysis to determine the effectiveness of some of the characterization techniques adopted for the inhibition studies. Also, a methodology blueprint for specific clay mineral types is highly recommended for future researchers to help reduce the uncertainty associated with the reported outcomes of these active clay minerals. At least five characterization techniques such as linear swelling test (LST), scanning electron microscopy (SEM), x-ray diffraction (XRD), bulk hardness test (BHT), and wettability alteration test (WAT) to be conducted for any experimental procedure to be able to understand in detail the inhibitive mechanism of the applied inhibitors. Environmentally friendly inhibitors that are cheap, pollution-free with excellent stability in harsh environments are highly encouraged since they can be sustained and have good inhibition potential.

Mechanism of pore relative humidity on salt swelling characteristics in sulfate saline soil

Crystallization of sodium sulfate into mirabilite in sulfate saline soil harms the soil potential and intensifies the reparative expenses for subgrade. However, the effects of pore relative humidity (PRH) on the salt swelling behavior have not been thoroughly explored. The multiple-humidity cycles experiments, in this paper, were performed to investigate salt swelling behavior in sulfate saline soil. The effects of different salinity, temperatures, and PRH values on salt swelling displacement (SSD) and salt swelling rate (SSR) of sulfate saline soil were analyzed. The X-ray Diffraction (XRD) technique was employed to investigate the mineral composition of post-experiment soil samples. All test results show that the SSD and SSR of soil samples increase with the increase of PRH and salinity and decreases as the increasing temperature. The enhancement of salt swelling in the presence of PRH was 80-90-80%. Besides, XRD results denote that the existence of mirabilite in the test soil samples verified for the salt swelling to be closely related to PRH in terms of microstructure. All the results further improve the mechanism of salt swelling in sulfate saline soil in the presence of PRH, which is of great significance to analysis and remediation of salt swelling behavior.

Growth Mechanism of Micro/Nano Metal Dendrites and Cumulative Strategies for Countering Its Impacts in Metal Ion Batteries: A Review.

Metal-ion batteries are capable of delivering high energy density with a longer lifespan. However, they are subject to several issues limiting their utilization. One critical impediment is the budding and extension of solid protuberances on the anodic surface, which hinders the cell functionalities. These protuberances expand continuously during the cyclic processes, extending through the separator sheath and leading to electrical shorting. The progression of a protrusion relies on a number of in situ and ex situ factors that can be evaluated theoretically through modeling or via laboratory experimentation. However, it is essential to identify the dynamics and mechanism of protrusion outgrowth. This review article explores recent advances in alleviating metal dendrites in battery systems, specifically alkali metals. In detail, we address the challenges associated with battery breakdown, including the underlying mechanism of dendrite generation and swelling. We discuss the feasible solutions to mitigate the dendrites, as well as their pros and cons, highlighting future research directions. It is of great importance to analyze dendrite suppression within a pragmatic framework with synergy in order to discover a unique solution to ensure the viability of present (Li) and future-generation batteries (Na and K) for commercial use.

Revealing crucial effects of temperature and salinization on swelling behavior of montmorillonite

Thermal and saline environment significantly affects the swelling behavior of montmorillonite (Mt) that is crucial for the safety of engineering barrier. However, the swelling mechanism of Mt under non-isothermal and saline environment remains poorly understood. A molecular Na-Mt model is proposed to analyze the swelling pressure change of Mt under various non-isothermal and saline conditions. The swelling mechanism of Mt at various salt solutions and temperatures is discussed based on analyses of the water concentration profile, hydration energy of Mt-salt solution system, and hydration state of interlayer cations. We find that the critical temperature that differentiates the negative and positive correlations between swelling pressure of Mt and temperature under different saline environments coincides with the hydration state saltation temperature identified from radial distribution function. Our research shows that the hydration energy of Mt and the hydration state of interlayer cations jointly control the swelling of Mt, via governing the water migration in Mt-salt solution system.

Molecular Dynamics Simulation of the Mechanical Behavior of Mixed-Layer Clay upon Hydration

A proper understanding of the the mechanical behavior of clay minerals is of crucial importance in earth sciences, soil mechanics, and geotechnical engineering. Although more than seventy percent of all clays are of mixed layer types, the vast majority of the previous studies are devoted to pure clays, which make the hydraulic and mechanical properties of the widespread mixed-layer clay (MLC) and its role in soils are little understood, especially the most common illite-montmorillonite (I-M) mixed-layer clay (MLC). This research reports on a molecular dynamics (MD) study of the differences in mechanical behavior between I-M MLC containing mixed K+ and Na+ and Na-montmorillonite (Na-MMT). The variations of key components in stiffness matrix with hydration have been analyzed. It is found that the stiffness tensor of two types of clay could be split into two groups: the in-plane coefficients (C11, C12, C22, and C66) and the out-of-plane coefficients (C13, C23, C33, C44, and C55). Due to the different forms of the support force of the clay layered structure in the two directions, they exhibit significantly different hydration mechanisms. Moreover, the I-M MLC is more difficult to hydrate and swell due to the asymmetric I-M interlayer and the existence of K+, and its ability to resist deformation is stronger than Na-MMT. This work offers insight into the molecular mechanism for initial swelling and mechanical behavior in widespread MLC. This will help to decipher its specific role in soils and controlling clay swelling.

An experimental study on the mechanical characteristics of Li‐ion battery during overcharge‐induced thermal runaway

Lithium batteries are prone to swelling during overcharge, which leads to a huge external force in modules and poses a potential threat to electric vehicles. Therefore, it is extremely important to understand the swelling mechanism of lithium batteries in-depth. In this paper, expansion force evolution during overcharge-induced thermal runaway process for large format lithium-ion battery with Li(Ni0.5Co0.2Mn0.3)O2 cathode is investigated. The rupture of the battery shell due to huge swelling is proved as the trigger of the thermal runaway event. In detail, the expansion force increases dramatically with the state of charge, which can be up to 3400 N. And it is a highly dynamic quantity with four obvious inflection points during overcharge, indicating a strong relationship with failure mechanisms. The inherent failure mechanism behind expansion force is investigated using both in-situ and ex-situ measurement techniques. The results revealing that the early abnormal expansion of the battery is caused by lithium dendrite and lithium plating. The rapid expansion mainly caused by CO, which is produced by incomplete electrolyte oxidation, leads to the rupture of the battery shell and thermal runaway events. This paper aims to unravel the mystery of lithium battery swelling during overcharge and provide valuable guidance to mitigate the overcharge risk induced by battery swelling.

Effect of basicity on the reduction swelling behavior and mechanism of limestone fluxed iron ore pellets

Limestone fluxed iron ore pellets are reduced in CO-rich atmosphere generally accompanied by swelling behavior. If the reduction swelling index (RSI) exceeds the normal range (≥20%), it will seriously hinder the stable and anterograde production of iron making. To better guide the industrial production, the effect of binary basicity (CaO/SiO2) on the reduction swelling behavior and mechanism of limestone fluxed iron ore pellets was investigated. Meanwhile, X-ray diffraction technique was used to analyze the phase transformation in pellets with different basicity during the reduction process, and the microstructures of different substances were examined by SEM-EDS. The above researches confirmed that the crystal volume expansion caused by crystal structure transformation during hematite (α-Fe2O3) reduced to maghemite (γ-Fe2O3) was the fundamental reason for the swelling of limestone fluxed pellets. Low basicity (0.4–0.8) amplified the volume expansion produced in this process, while high basicity (1.0–1.2) reversed it. This inconsistency stemmed from the difference in the composition of binding phase. Compared with calcium iron silicate in low basicity pellets, complex calcium ferrite (SFCA) as the binding phase of high basicity pellets had excellent reducibility, which promoted uniform reduction rate of high basicity pellets. The increased of SFCA content i reduced the quantities of hematite and effectively inhibited swelling of pellets. From this investigation, increasing the basicity above 1.0 to promote the formation of SFCA was an effective way for decreasing the reduction swelling index of limestone fluxed pellets.

Stretchable conductive elastomer composites based on a processing of Ag+ swelling, in situ reduction, and drying shrinkage

We present a simple preparation method for the stretchable conductive nanocomposites which can still maintain the activity and electrical stability under the condition of large-scale mechanical processing. The preparation scheme takes advantage of the swelling mechanism of the polymer and introduces the precursor silver ions into it. A reducing agent is then incorporated into the polymer matrix, and the silver ions in the polymer matrix are reduced in situ to form silver nanoparticles. Drying the solvent inside of the polymer causes the polymer to spontaneously shrink, resulting in the tight accumulation of silver nanoparticles. Subsequent experimental tests show that the prepared composite material stretched to its original swelling state still retains its high conductivity. When the content of silver reaches the saturation value, its maximum conductivity is 2500 S/cm, and its high conductivity at 80% deformation is retained. The composite material also shows certain fatigue resistance.

Functional effectiveness of double essential oils@yam starch/microcrystalline cellulose as active antibacterial packaging

In this work, two combinations of double EOs, i.e., α-terpineol: eugenol (α-T:Eu) and carvacrol:eugenol (CA:Eu), are used to develop the active antibacterial films of double EOs@yam starch/microcrystalline cellulose (EOs@SC). The hydrogen-bonded networks in SC matrix are conducive to thermostability enhancement and the film of SC25 is determined for EO incorporation. The interactions between EOs and SC matrix are also hydrogen bonds and the double EOs@SC are smooth at ratio of ≤2:2 for α-T:Eu or CA:Eu. The ultimate film properties are dependent on the incorporated EOs. The release of EOs is well controlled by two mechanisms of diffusion (predominant) and swelling (secondary). Synergetic antibacterial activity occurs on double EOs@SC. The shelf life of pork can be extended by 1 day at 25 °C by the two typical films of α-T2:Eu2@SC and CA2:Eu2@SC. Moreover, EOs@SC can be well degraded in humus soil. Thereby, the target films will have great potential in active packaging to extend the shelf life of food.

Deformation effect on nuclear density profile and radius enhancement in light- and medium-mass neutron-rich nuclei

Abstract The mass number dependence of nuclear radii is closely related to the properties of nuclear matter. It is known that most nuclei exhibit some deformation. We discuss how the nuclear density profile is modified by nuclear deformation to elucidate the enhancement mechanism of nuclear radii through a systematic investigation of neutron-rich Ne, Mg, Si, S, Ar, Ti, Cr, and Fe isotopes. Skyrme–Hartree–Fock calculations are performed in a 3D Cartesian grid to describe the nuclear deformation in a non-empirical way. The role of nuclear deformation in nuclear density profiles is explored in comparison to calculations with a spherical limit. We find correlations between nuclear deformation and the internal nuclear density. The evolution of nuclear radii appears to follow the core swelling mechanism recently proposed in spherical nuclei [W. Horiuchi and T. Inakura, Phys. Rev. C 101, 061301(R) (2020)], and the radius is further enhanced by nuclear deformation. This study demands further theoretical and experimental investigations for the internal density.

A study of water‐induced elementary hemp fiber swelling and the reinforced polypropylene composite expansion

AbstractTo deeply understand the swelling mechanism, the water swelling ratio and direction of elementary hemp fiber and the reinforced polypropylene (PP) composites were analyzed by both experimental methods and numerical simulation. The fiber swelling force was also calculated based on Flory–Rehner theory. The results showed that the simulated fiber radial swelling ratio of 6.5% is slightly higher than the measured one of 5.6%. For the reinforced composites, the simulated cross‐sectional expansion of 3.7% is very close to the measured one of 3.5%. This indicates that fiber mainly swells along its radial direction and the composite expansion is affected by not only fiber swelling ratio and direction but also fiber volume fraction and orientation. The proposed simulation model could easily estimate the swelling ratio and rate of plant fiber and the reinforced composites from their weight gain data. The generated swelling force of fiber is almost 850 MPa at the beginning and decreases to zero until achieving saturation state, which is much higher than the constraint stress of PP matrix and drives composite water expansion behavior. It is concluded that reducing the mixing entropy of plant fiber with water should be an effective approach to inhibit composite water expansion and improve its dimensional stability. The obtained results are beneficial for constructing a water absorption and service life prediction model of shortcut hemp fiber composites.

Effect of the reaction of ammonia gas on the swelling of metallic iron and its oxides during nitriding processes

In order to study the relationship and effect of nitrogen gas in the reducing gases used in the reducibility tests of iron oxides, under isothermal conditions, a test scheme was executed using ammonia gas, such that its decomposition of the gas in the reactor produced a mixture of H2 and N2 gases. Furthermore, the addition of 6% NH3 in a 28% H2 and 68% N2 gas stream was planned to obtain a gas composition of 70% N2 and 30% H2. This would allow comparing the reducibility curves between both conditions, assuming that the possible difference between both conditions to compare the volume changes of the reduced samples. The difference to be studied will be based on the estimation and comparison of the rate of formation of metallic iron in the stages of reduction of Hematite / Magnetite / Wustite (FeO), as well as the effects of nitrogen absorbed by the fresh metallic iron produced, or present. in iron catalysts to produce ammonia, from the reducing gas mixture, on the volume change of the samples. Likewise, the catastrophic volume changes caused by nitrogen are compared by comparing sources of this gas in solid carbonaceous reducers.
 Keywords: Gaseous Reduction, Direct Reduced Iron, isothermal tests.
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