Swelling Force Research Articles

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.

Comparison of six modification methods on the chemical composition, functional properties and antioxidant capacity of wheat bran

The effects of six modification methods (microwaving, steam, extrusion, superheated steam, fermentation and enzymatic treatments) on the chemical composition, processing quality characteristics and antioxidant capacity of wheat bran were determined. Compared with unmodified control bran, all six modification methods had a significant impact on the physical and chemical properties and antioxidant capacity. Microwaving, steam, extrusion, superheated steam and enzymatic treatments could significantly increase the content of folic acid, but decreased the content of vitamin B2. Fermentation increased the proportion of soluble dietary fiber and changed the ratio of insoluble/soluble dietary fiber from 13.65:1 to 8.74:1. The content of water extractable arabinoxylan after microwaving, extrusion and fermentation increased by 12.3%, 33.6% and 46.4%, respectively. Extrusion increased the swelling force of the bran. All modifications increased the total phenolic and ferulic acid contents and the bound ferulic acid content was highest after the steam and extrusion treatments. Enzymatic treatment reduced the DPPH radical scavenging capacity by 16.9%, microwaving increased the ABTS radical scavenging capacity by 12.53% and extrusion increased the ORAC(oxygen radical absorbance capacity) by 4.15%. Overall, extrusion resulted in the greatest improvements in the nutritional and processing qualities of bran, and the greatest increases in its phenolic content and antioxidant capacity.

Changes of Water/Ice Morphological, Thermodynamic, and Mechanical Parameters During the Freezing Process

To reduce ice adhesion hazards, optimize or develop the anti/de-icing methods, it is necessary to understand the change of freezing parameters during the freezing process, such as thermodynamic, morphological, and mechanical parameters. The present study investigates the freezing characteristics by purpose-built devices to describe the freezing process quantitatively. Morphological parameters were calculated the reverse engineering. The results showed that the inner temperature and morphology of water droplet were obviously changed, and the freezing process could be mainly divided into three stages: initial and spreading, freezing, and steady-state. Moreover, an experimental apparatus that measured the phase swelling force was built on investigating the freezing process of water from the mechanical aspect. It was found that the swelling force generated from the freezing process of 2473 mm3 water could reach 46.38 N. The generation process of swelling force could also be separated into three stages: non-expansive stage, increasing stage, and stable stage. The formation stage of swelling force was similar to that of ice. Combining the measured expansion force with the calculated freezing parameters based on the observed test, the freezing process of water could be better understood. The study would help researchers and engineers understand the freezing process and provide some freezing characteristics parameters for the anti/de-icing research.

Moisture induced straining of the cellulosic microfibril

Moisture absorption in the cell wall structure of wood is well known to induce considerable swelling of the wood exerting high expansion forces. This swelling is mainly induced by the sorptive action of the hydroxyl groups of the carbohydrate wood polymers; cellulose and hemicelluloses. On the ultrastructural level, there are, however, still questions with regard to the detailed deformations induced by this moisture absorption. Here, FTIR spectroscopy and synchrotron-radiation-based X-ray diffraction were used on paper samples to study the deformation of the cellulose crystals as a consequence of moisture absorption and desorption. Both techniques revealed that the moisture absorption resulted in a transverse contraction of the cellulose crystals accompanied by a somewhat smaller elongation in the cellulose chain direction. The deformations were found to be a direct response to the increased moisture content and were also found to be reversible during moisture desorption. It is hypothesised that these deformations are a consequence of the swelling forces created by the combined longitudinal and lateral expansions of the non-crystalline cellulose molecules and the glucomannan hemicellulose aligned along the cellulose crystals. These forces will impose a lateral contraction of the cellulose crystals, as well as a longitudinal extension of it.Graphic abstract

Effect of interlayer cations on montmorillonite swelling: Comparison between molecular dynamic simulations and experiments

The understanding of the swelling phenomenon of montmorillonite is essential to predict the physical and chemical behavior of clay-based barriers in geoenvironmental engineering. This study investigated the crystalline swelling behavior of montmorillonite with different interlayer cations including monovalent Na, K, and Cs and divalent Ca and Sr by molecular dynamics simulations and experimental measurements including X-ray diffraction and water vapor adsorption. The stepwise swelling behavior for Na- and Ca/Sr-montmorillonite demonstrated good agreement between molecular dynamics (MD) simulated and experimental results. The swelling curves of K- and Cs-montmorillonite remaining in the 1-hydrated state even at high relative humidity showed systematic discrepancies between MD simulations and experimental results. The comparative discussion between the experimental and MD derived swelling curves offer insights that may help to understand the swelling mechanism of montmorillonite and the dependence on interlayer cations. The water content in the interlayer and external surface in five homoionic montmorillonite was strongly correlated to the hydration number of each ion. On the basis of these comparisons, the hydration free energy of interlayer cations seems to contribute greatly to the total driving force for the crystalline swelling of montmorillonite. An additional key factor is the preference of an outer- or inner-sphere complex of interlayer cations and the distribution of cations in the interlayer space. This effect has a considerable impact in the case of monovalent cations and results in different swelling behavior between the outer-sphere Na and inner-sphere K and Cs ions.

Fungal chitosan as membranous material modified by atmospheric plasma

Objective: This study produced a fungal chitosan membrane extracted from Rhizopus stolonifer, as well as its modification using dielectric barrier discharge plasma (DBD), aiming to improve the physicochemical characteristics of the membrane, optimizing its use in the medical research field. Method: The obtained chitosan was physically and chemically characterized (Molecular Weight, Fourier Transform Infrared, X-ray Diffraction), later were produced fungal chitosan membranes and DBD plasma was applied. The membranes were characterized before and after plasma application using the tests contact angle, swelling and atomic force microscopy (medium roughness) analyzes. Results: A fungal chitosan with a yield of 16.73 mg/g, and an apparent molecular weight of 4 kDa was obtained, being considered of low molecular weight and high degree of deacetylation (84%). It was possible to obtain the membrane and after application of DBD plasma, the contact angle dropped from 77.5° to 30.9°, making it more hydrophilic. Conclusion: Thus, the efficiency of the technique for increasing the hydrophilicity of the fungal chitosan membrane without the additive of chemical reagents during the process was confirmed and the membrane formed is a promising alternative can be used in different ways in the medical area.

Bonding mechanism and performance of rectorite/ball clay bonded unfired high alumina bricks

In this study, the bonding mechanism and normal/high temperature performance of rectorite clay or ball clay bonded unfired high alumina bricks were investigated by using different techniques (XRD, TG-DSC, SEM, particle size distribution and rheology). The results showed that clay particles are separated into layer structural units in water due to the hydration swelling and electrostatic repulsive force, and rectorite layer structural units have larger aspect ratio than ball clay. Rectorite layer structural units form band-type structure with “face to face” after drying results in better bonding performance than ball clay (card-house structure with “edge to face”). The cold crushing strength of 9% rectorite/ball clay bonded unfired high alumina bricks after firing at the dehydroxylation temperature for 3 h reach 71 MPa and 50 MPa, respectively, and which can satisfy the strength requirement for the transportation and use of most high alumina bricks. The secondary mullitization and lower liquid phase content of ball clay bonded unfired high alumina brick under high temperature cause it has higher refractoriness under load and lower linear shrinkage than rectorite clay bonded brick. The T0.6 refractoriness under load of 9% rectorite/ball clay bonded unfired high alumina brick are 1262.6 °C and 1580.3 °C, respectively. Thus, the 9% ball clay bonded unfired high alumina bricks have wider service temperature range than 9% rectorite bonded bricks.

ESTIMATES OF THE EIGENVALUES AND EIGENFUNCTIONS OF OPERATOR ARISING IN SWELLING PRESSURE MODEL

Swelling forces from materials confined by structures can cause structural deformations and instability. Due to the complexity of interactions between expansive solid and solid-liquid equilibrium, the forces exerting on retaining structures from swelling are highly nonlinear. This work is our initial attempt to study a simplistic initial/boundary value problem based on the Euler-elastic beam theory and some swelling force model. In this paper, we study a nonlinear problem for the equation of a beam. The self-adjointness of the operator corresponding to the nonlinear problem for the Euler equations is proved. Two-sided estimates of the eigenvalues of the operator in question are established. Two-sided estimates of the eigenfunctions of the operator of the initial-boundary value problem for the beam equation are also obtained.

Swelling Force in Lithium-Ion Power Batteries

To meet the demand for high energy and long life of electric vehicles, lithium-ion batteries using Ni–Co–Mn ternary materials as cathode have become the focus of industrialization. To design a safe...

Modeling and measuring the absorption-induced expansion of swellable organically modified silica

We present a theoretical framework that describes the force generated by the expansion of swellable organically modified silica (SOMS) upon exposure to organic solvent. The total swelling force, produced from the differential contributions of localized swelling domains, is related logarithmically to the amount of material confined to a rigid space. The model is further parameterized according to the physical dimensions of that space and the intrinsic swellability of SOMS. This mathematical representation is validated experimentally using a piston force sensor apparatus, which shows that the solvent-induced force and pressure exerted by SOMS increase logarithmically with the amount of material that is present. Comparison with theory implies that the commercially available varieties of SOMS CyclaSorbTM and OsorbTM have Young’s expansion moduli YC ∼ 0.8 MPa and YO ∼ 0.7 MPa, respectively, which succinctly quantifies their relative behavior. The theoretical model and experimental technique should be widely applicable to other swellable and stimuli-responsive materials.

Development and evaluation of zopiclone compression coated tablet for time-controlled pulse release: Mechanism and in vivo study

Early-morning awakening is a special insomnia characterized with circadian rhythm. In this study, zopiclone (ZOP), one of the common hypnotics, was selected to prepare zopiclone pulse release tablet via compression coating. Single-factor analysis combined with Box–Behnken design (BBD) was used to optimize the formulations. Finally, ZOP compression coated tablets (CCTs) with burst release after a 2.5–3 h lag time (Tlag) were successfully obtained. A study of mechanical properties revealed that the generation of Tlag resulted from the break of the mechanical equilibrium between core swelling force and coating fracture strength, moreover, the time-varying curves of these two forces were both consistent with the Weibull distribution. Compared with the commercial tablets, CCTs in beagle dogs showed a significant delay about 2.67 h which was similar to the Tlag in vitro. There was no significant difference in main pharmacokinetic parameters such as T1/2, AUC and Cmax. The relative bioavailability was 106.64%, indicating that Tlag of ZOP CCTs had no effect on the following pharmacokinetic process. Furthermore, a good in vivo-in vitro correlation (IVIVC) of ZOP CCTs was verified (R2 = 0.9625). The development of the ZOP CCTs provided a modified drug delivery system for early-morning awakening insomnia.

A Decentralized (Ex Vivo) Murine Bladder Model with the Detrusor Muscle Removed for Direct Access to the Suburothelium during Bladder Filling.

Previous studies have established the release of chemical substances from flat bladder mucosa sheets affixed in Ussing chambers and exposed to changes in hydrostatic pressure or mechanical stretch and from cultured urothelial cells upon hydrostatic pressure changes, stretch, cell swelling, or drag forces, and in bladder lumen at end of filling. Such findings led to the assumption that these mediators are also released in suburothelium (SubU)/lamina propria (LP) during bladder filling, where they affect cells deep in the bladder wall to ultimately regulate bladder excitability. There are at least two obvious limitations in such studies: 1) none of these approaches provide direct information about the presence of mediators in SubU/LP, and 2) the stimuli used are not physiological and do not recapitulate authentic filling of the bladder. Here, we discuss a procedure that enables direct access to the suburothelial surface of the bladder mucosa in the course of bladder filling. The murine detrusor-free preparation we created closely resembles filling of the intact bladder and allows pressure-volume studies to be performed on the bladder in the absence of confounding signaling from spinal reflexes and detrusor smooth muscle. Using the novel detrusor-free bladder model, we recently demonstrated that intravesical measurements of mediators cannot be used as a proxy to what has been released or present in the SubU/LP during bladder filling. The model enables examination of urothelium-derived signaling molecules that are released, generated by metabolism and/or transported into the SubU/LP during the course of bladder filling to transmit information to neurons and smooth muscle of the bladder and regulate its excitability during continence and micturition.

Atomistic simulation of defect-dislocation interactions in concentrated solid-solution alloys

The interaction between point defects and dislocations plays a crucial role in governing material properties and microstructural evolutions under external stimuli, such as mechanical deformation and irradiation. Here, we present an atomistic study of the interactions between point defects and dislocations in concentrated solid-solution alloys (CSAs). Using molecular statics and kinetic Monte Carlo methods, we demonstrate that the strain energy and stress field distribution induced by a dislocation in CSAs are highly inhomogeneous along the dislocation line, which leads to heterogeneity of defect-dislocation interactions. Specifically, the interactions are spatially different and screened by the random arrangement of different elemental species. Such localization of defect-dislocation interaction indicates that the ``dislocation-bias'' mechanism that is a driving force for radiation-induced void swelling can be suppressed in concentrated alloys.

Color-Switchable Polar Polymeric Materials.

Spiropyran is an important mechanophore, which has rarely been incorporated as a cross-linker in polar polymer matrices, limiting its applications in innovative mechanochromic devices. Here, three spiropyrans with two- or three-attachment positions were synthesized and covalently bonded in polar poly(hydroxyethyl acrylate) (PHEA), to achieve color-switchable materials, triggered by light and when swollen in water. The negative photochromism in the dark and mechanical activation by swelling in water were investigated. Measurements of negative photochromism were conducted in solution and cross-linked PHEA bulk polymers, with both showing color reversibility when stored in the dark or on exposure to visible light. The force of swelling in water was sufficient to induce the ring-opening reaction of spiropyran. It was found that tri-substituted spiropyran (SP3) was less influenced by the polar matrix but showed the fastest color activation during swelling. SP3 also showed accelerated ring opening to the colored state during the swelling process. Bleaching rates and color switchability were investigated under swollen and dehydrated conditions. The effect of cross-link density on the swelling activation was explored to better understand the interaction between the mechanophore and the polar environment. The results demonstrated that influences from both the polar environment and the mechanochromic nature of spiropyran had an impact on the absorption intensity, rate of change, and the decoloration rate of the materials. This study provides the opportunity to manipulate the properties of spiropyrans to afford materials with a range of color-switching properties under different stimuli.

Tuning of the dynamics of metal ion crosslinked hydrogels by network structures.

The dynamic mechanical response of hydrogels is correlated with the intrinsic dynamics of the crosslinkers. Our experiments and theory show that polymer network structures can also affect the dynamic response of hydrogels by transducing swelling forces to the crosslinkers. Our results suggest a novel route to engineer complex time-dependent mechanical properties of soft materials for biomedical applications.

The influence of vermiculite on the ash deposition formation process of Zhundong coal

Zhundong coal, rich in the Alkali and Alkaline Earth Metal elements, causes severe ash deposition during the combustion in many power plants. In this paper, the influence of vermiculite, as an additive, on ash deposition formation and the corrosion phenomenon caused by ash deposition are investigated in a drop tube furnace system. The formation process of ash deposition under real working condition can be simulated in this furnace system. The results show that vermiculite has a significant inhibition effect on the formation and growing process of ash deposition, as well as the corrosion phenomenon. At the beginning of ash deposition, the swelling vermiculite can effectively absorb the SO2 in the flue gas, which restrains the formation of Na2SO4 in the inner ash, close to the surface of heat exchangers. The mineral in internal inner ash gets changed and the phenomenon of corrosion on the heat exchangers surface gets alleviated. Meanwhile, the external inner ash presents with loose structure instead of the molten condition, which lowers possibility for ash deposition to grow. In outer ash deposition, close to the flue gas, the content of layered particles with high melting point, as Mg2SiO4, increases and viscous particles, like Ca2Al2SiO7, are separated from each other by the force of the vermiculite swelling. As a result, adding vermiculite makes it hard for ash deposition to form and grow. According to the experiments, with more than 5% blending ratio of vermiculite, the vermiculite additive has a positive effect on restricting the ash deposition.

Utilizing swelling force to decrease the ice adhesion strength

The phase transformation that occurs during water freezing process is accompanied by volume expansion and the release of latent heat. The swelling force generated by this phase transformation can have a harmful impact on structural safety and integrity, as it can lead to bursting in roads, water pipes and reservoir dams. So, why not effectively adopt the swelling force as the active de-icing power to diminish the stability of the contact interface. This paper proposes a new method to remove this accumulated ice by using polymethyl methacrylate (pmma) and 6061 aluminum alloy with pits as substrate materials. Pits were filled with solutions of different freezing points; owing to the different freezing point between the pit solution and water, their phase transformations occurred at different time, where the solutions in the pit would freeze more slowly than the surface water. The generated phase swelling force directly acted on the contact interface and decreased the stability of the interface to decrease the ice adhesion strength. The experimental results showed that the ice adhesion strength was obviously affected and reduced by the swelling force in contrast to the ice adhesion strength on the smooth sample, and the reduction in ice adhesion strength changed depending on the filling solution. Compared to the ice adhesion strength of the specimen without pits, the frozen ice was completely separated from the ice-pmma interface owing to the water filling the pit. The ice adhesion strength on the surface of the aluminum alloy sample filled with 10% ethanol solution was reduced by 81.42%. Utilizing the phase swelling force to reduce the adhesion strength enhances the active de-icing ability of the material, providing a novel method for developing new anti-icing methods.

Kinetics of Domain Alignment in Block Polymer Thin Films during Solvent Vapor Annealing with Soft Shear: An in Situ Small-Angle Neutron Scattering Investigation

We employed small-angle neutron scattering (SANS) to identify the kinetic pathways between disordered and ordered states in block polymer (BP) thin films subjected to solvent vapor annealing with soft shear (SVA-SS), which enabled the optimization of large-scale nanostructure ordering and alignment. The judicious incorporation of deuteration in poly(deuterated styrene-b-isoprene-b-deuterated styrene) (dSIdS) films (≈200 nm thick) provided sufficient contrast in the SANS experiments to overcome the diffuse scattering contribution from thicker (nondeuterated) polydimethylsiloxane (PDMS) pads (≈500 μm thick) and permit the in situ tracking of BP nanostructure responses to swelling, deswelling, and shear forces. We determined that as the dSIdS and PDMS swelled during SVA-SS, the lateral expansion of the PDMS across the pinned film induced a shear force that promoted chain mixing and nanostructure disordering in our solvent swollen systems. As solvent was removed from the films (deswelling), smaller grains beg...

A brief review of mechanisms for carbon dioxide sequestration into aquifer reservoirs

This paper presents a thorough understanding of carbon dioxide (CO2) gas sequestration mechanisms taking place at the time of injection, post injection and settlement of CO2 into the aquifer reservoirs. It also presents a broad model consisting of two positive components and one negative component to briefly describe the microscopic mechanisms that occur during CO2 trapping. The force of displacement and the force of pore space enlargement to increase the CO2 storage capacity are positive influencing factors for CO2 trapping in the aquifer reservoirs. Alternatively, the force of swelling is the negative component of the model. This short review will discuss the current scenario of understanding of CO2 trapping mechanisms, structural trapping mechanisms, kinetics of CO2 dissolution and future challenges and developments of carbon capture and storage projects. The present study will deliver a complete understanding of microscopic phenomena during CO2 trapping into aquifer reservoirs apart from the existing mechanisms.

Evaluation of the swelling behaviour of iota-carrageenan in monolithic matrix tablets

The swelling properties of monolithic matrix tablets containing iota-carrageenan were studied at different pH values, with measurements of the swelling force and characterization of the profile of the swelling curve. The swelling force meter was linked to a PC by an RS232 cable and the measured data were evaluated with self-developed software. The monitor displayed the swelling force vs. time curve with the important parameters, which could be fitted with an Analysis menu. In the case of iota-carrageenan matrix tablets, it was concluded that the pH and the pressure did not influence the swelling process, and the first section of the swelling curve could be fitted by the Korsmeyer–Peppas equation.