Moisture Absorption Rate Research Articles

Innovative Hygroscopic Material for Humidity Regulation: Diatomaceous Earth Composite Porous Ceramic

Urbanization in hot and humid regions such as southern China has increased the demand for comfortable indoor environments. In order to design a material for efficient passive indoor humidity regulation, this study investigates a composite material that combines the hygroscopic properties of salt and the adsorption capacity of diatomaceous earth (DE). Firstly, we prepared DE and boehmite into moisture-absorbing porous materials. Then, the initial DE-based sample was innovatively doped with SiO2 nanomaterials and loaded with LiCl to enhance the humidity regulation ability of the composite, especially in the adsorption and desorption ability of water vapour. The microstructure and phase composition of the composite samples were analysed, and we observed an increase in porosity, filling performance and capillary condensation upon the introduction of SiO2 nanoparticles. The hygroscopic salt loaded into the pores can absorb more water when exposed to the ambient humidity. This synergic effect can effectively improve the hygroscopic performance of the composite material while maintaining the stability of the physical and chemical properties. The optimized samples showed a moisture absorption rate of 28% in high-humidity environments, meeting moisture buffer value evaluation standards. The study’s findings lay the foundation for the future integration of these materials through advanced manufacturing technologies.

T700 Carbon Fiber/Epoxy Resin Composite Material Hygrothermal Aging Model.

The hygrothermal aging model, based on Fick's second law of diffusion, characterizes the degradation of engineering constants in T700 carbon fiber/epoxy resin composites. It focuses on changes in the tensile modulus, shear modulus, and transverse Poisson's ratio due to moisture absorption and temperature variations. The model validates through mass change observations before and after seawater immersion, along with surface morphology assessments and tensile experiments. The results reveal that the saturated moisture absorption rate for single-layer laminates in seawater immersion is 0.35%. Short-term seawater immersion at room temperature (≤60 days) does not induce cracks or defects (≥10 μm) on the composite's surface. The composite's modulus decreases as moisture absorption increases, with the longitudinal tensile modulus dropping by an order of 10-5%, while the other engineering constants decrease by an order of 10-3%. The modulus also decreases with rising temperature; the closer the temperature is to the matrix's glass transition, the faster the modulus declines, with the longitudinal tensile modulus decreasing by 0.84%, and the other engineering constants decreasing by 100%. This research provides valuable insights for the engineering applications of composite materials in marine environments.

Soy Protein Adhesive Enhanced Through Supramolecular Interaction with Tannic Acid Modified Montmorillonite.

The use of soybean meal (SM) as an alternative to petroleum-based resins in wood-based panels offers a solution to the problem of formaldehyde release. However, inherent drawbacks of soybean meal adhesives, such as poor toughness, low bond strength, and susceptibility to mold, have hindered their further development. In this study, a novel biomass adhesive, SM-MMT@TA, was developed based on supramolecular interactions between tannic acid (TA), montmorillonite (MMT), and soybean meal. Tannic acid was securely attached to the MMT surface through coordination bonds with Ca2+, Mg2+, and Al3+ ions, enhancing MMT's compatibility in the matrix via strong interfacial interactions. TA on the surface of MMT@TA effectively bonded with soy protein through strong hydrogen bonding, thereby increasing the crosslink density. As a result, the adhesive exhibited a wet shear strength of up to 1.75 MPa, which represents a 143.05 % increase compared to unmodified SM adhesive. Moreover, the moisture absorption rate of the adhesive was reduced to 26.79 %. Furthermore, abundant non-covalent interactions improved the adhesive's toughness, while natural polyphenols provided additional mold resistance. Overall, this study presents a new strategy for developing renewable, high-performance biomass-based adhesives.

Research on the Preparation Process of Mahuang Xixin Fuzi Decoction Granules

Abstract Objective The objective of this study was to investigate the preparation process of Mahuang Xixin Fuzi decoction granules based on the clinical pharmacological effects of the classic formulas and to control the quality of the product. Methods An orthogonal experimental design was used, with extraction yield and transfer rate of key ingredients as evaluation indicators, to optimize the extraction process of Mahuang Xixin Fuzi decoction. The granulation process was optimized based on indicators such as granule formation rate, dissolution rate, and moisture absorption rate. Results The optimal extraction process for Mahuang Xixin Fuzi decoction was determined as the following: using 10 times the amount of water to soak for 30 minutes, extracting three times, each for 60 minutes, with a concentrated extract relative density of 1.3 g/mL. A mixture of dextrin and starch at a 1:2 ratio was used as a binder for wet granulation. The granule formation rate, dissolution time, and dilution rate of three repeated batches showed relative standard deviation (RSD) values of 1.48, 2.83, and 1.55%. Conclusion This method is stable and feasible, providing valuable data for the industrial production of Mahuang Xixin Fuzi decoction granules and further research on this formulation.

High Absorption and Elasticity of a Novel Transgenic Silk with Egg Case Silk Protein from Nephila clavata.

Spider silk is part of a special class of natural protein fibers that have high strength and toughness: these materials have excellent comprehensive properties that are not found in other natural fibers (including silk) or most synthetic fibers. Spider egg case filaments have good hardness, can resist water, can protect spider eggs from external threats, have a significantly high initial modulus and high moisture absorption rate, and are expected to be used as a new generation of environmentally friendly natural polymer fibers and biomaterials. However, spiders are predatory and difficult to rear in large numbers, and it is also difficult to obtain spider egg case filaments in large quantities. Silkworms and spiders have a similar spinning system, and the use of transgenic technology in silkworms can obtain stable and high-yield exogenous gene proteins for a long time, representing an ideal bioreactor for the production of spider silk. In this study, the eukaryotic bioreactor and piggyBac transposon system were employed to recombinantly introduce the egg case silk protein of Nephila clavata (Nc-CYSP1) into the silkworm in the silkworm heavy-chain expression system. The results revealed that the silk glands produced a new type of transgenic silk with a significantly high initial modulus and high moisture absorption. In summary, this study provides an experimental reference for future research on the large-scale production and application of spider egg case filamentous protein, with great application prospects in the development of new environmentally friendly materials.

Modifying Bitumen with Recycled PET Plastics to Enhance Its Water Resistance and Strength Characteristics.

This study investigates the modification of bituminous mixtures by varying percentages of PET particles (1%, 3%, 5%, 8%, 10%, and 12% PET). The following methods were employed to analyze the samples: the ring-and-ball softening point determination method (ASTM D36/D36M-14), the Fraass breaking point determination method (EN 12593: 2015), the elongation determination method (EN 13589: 2014), and the needle penetration depth determination method (EN 1426: 2015). Optimal bitumen/PET ratios were identified to obtain modified bituminous mixtures (MBMs) with enhanced operational characteristics (5% and 8% PET). The physical and mechanical properties of the investigated bitumen samples and PET were determined. A comparative analysis of the modified bituminous mixture samples based on their physical and mechanical properties was conducted. Microstructures of the surface of modified bituminous mixture samples with varying modifier contents were obtained. An X-ray structural analysis was performed on the samples of modified bituminous mixtures with varying PET contents. The dependencies of the moisture absorption rate on time were determined for the samples of modified bituminous mixtures with different modifier contents. The values of the stress intensity factor were determined based on the number of loading cycles in fatigue tests using three-point bending for the samples of modified bituminous mixtures with varying modifier contents.

Robinia pseudoacacia Quickly Adjusts Its Water Uptake after Rainfall in Seasonally Dry Regions

Precipitation is a key factor affecting plant growth and development in seasonally arid regions. However, most of the traditional hydrological methods mainly select typically sunny days for sampling, and the immediate water absorption strategy of plants during and after rainfall is still unclear. This study used stable hydrogen and oxygen isotope technology to study the soil moisture absorption rates of Robinia pseudoacacia and the soil moisture content at different soil layers at different sampling times (0, 6, 12, 18 and 24 h) after rainfall. The results showed that the moisture content of the shallow soil layer decreased, while that of the deep soil layer increased over time after rainfall. R. pseudoacacia mainly utilized water from the 0–20 and 20–40 cm soil layers at 6 h after rainfall, which accounted for 36.52% and 22.25% of the rainfall, respectively. At 24 h, the 40–60, 60–80 and 80–100 cm soil layers contributed 25.25%, 18.44% and 24.45% of the water content, respectively. The shallow soil layer retained more rainfall within 6 h after rain fell, and the water retention ratio of the medium–shallow soil layer (0–60 cm) increased to 48.4%, retaining more water at 14–20 h. At 12 h, the medium–shallow soil layer (0–60 cm), runoff and groundwater constituted 37.1%, 14.4% and 15.7% of the precipitation, respectively, and rainfall retained in the deep soil layer (60–100 cm) accounted for 32.8%. In summary, R. pseudoacacia tends to use a large amount of shallow soil water in seasonally arid regions when precipitation supplements the surface soil moisture content and it utilizes deep soil water when the rainfall infiltrates and recharges the deep soil layer. Since R. pseudoacacia is sensitive to precipitation, it can quickly adjust its water absorption depth range during the short-term rainfall period to absorb as much precipitation as possible.

Research Progress on Moisture-Sorption Actuators Materials.

Actuators based on moisture-sorption-responsive materials can convert moisture energy into mechanical/electrical energy, making the development of moisture-sorption materials a promising pathway for harnessing green energy to address the ongoing global energy crisis. The deformability of these materials plays a crucial role in the overall energy conversion performance, where moisture sorption capacity determines the energy density. Efforts to boost the moisture absorption capacity and rate have led to the development of a variety of moisture-responsive materials in recent years. These materials interact with water molecules in different manners and have shown diverse application scenarios. Here, in this review, we summarize the recent progress on moisture-sorption-responsive materials and their applications. We begin by categorizing moisture-sorption materials-biomaterials, polymers, nanomaterials, and crystalline materials-according to their interaction modes with water. We then review the correlation between moisture-sorption and energy harvesting performance. Afterwards, we provide examples of the typical applications using these moisture-sorption materials. Finally, we explore future research directions aimed at developing next-generation high-performance moisture-sorption materials with higher water uptake, tunable water affinity, and faster water absorption.

Investigation into diffusion behaviours of moisture in asphalt film using Fourier transform infrared spectroscopy

ABSTRACT To reveal the moisture damage mechanism of asphalt pavement and clarify the process of moisture damage to asphalt films, the diffusion behaviours of moisture in asphalt films were analysed. The findings indicate that during the first stage of the water bath process, the moisture diffusion coefficient in asphalt films is considerable and the diffusion rate is rapid. As the moisture diffusion rate increases, the free moisture content in asphalt films tends to saturate. Subsequently, partial free moisture transitions into bound moisture results in a decline in the diffusion coefficient of asphalt films and a reduction in its moisture absorption rate. As the temperature rises, the moisture diffusion coefficient in asphalt film and the maximum saturation amount of moisture that can be absorbed by asphalt films increase. The moisture diffusion behaviour is not readily discernible at a low temperature. The diffusion coefficients of moisture in unmodified asphalt films in the two stages are higher than those in modified asphalt films. The first stage of moisture diffusion in unmodified asphalt films occurs at a faster rate than in modified asphalt films. It is further verified that unmodified asphalt is more subjected to moisture damage.

Measurement of the water vapor transmission rate at temperatures above 100 °C

ABSTRACT Water vapor transmission rate (WVTR) and water vapor permeability coefficient were measured at temperatures between 110 and 138°C using the modified cup method. The cup, placed in a Highly Accelerated Stress Test chamber, allowed water vapor to permeate the sample film attached to the cup. The WVTR was determined based on the increase in mass of the cup. To prevent sample damage during measurement, a cup with a pressure adjustment mechanism was utilized. Carrier-incorporated phosphorus pentoxide was used as the desiccant instead of anhydrous calcium chloride to ensure a consistent moisture absorption rate, especially at high temperatures. The water vapor permeability coefficients for the polycarbonate, polyimide, and adhesive films were distributed on an approximately straight line in the Arrhenius plot. Additionally, the Arrhenius plots for the polyethylene terephthalate and polyethylene naphthalate films captured the permeability bending point near the glass transition temperature. To accurately measure the high-temperatureWVTR, upper and lower limits were established for the weighing interval, cup mass gain, and WVTR measurement range.

Soybean protein “mechanically interlocked” bonding of polysaccharide and MXene to improve the strength and toughness of biomass adhesive

Soybean protein “mechanically interlocked” bonding of polysaccharide and MXene to improve the strength and toughness of biomass adhesive

Self-assembled composite fabrics of lotus stem fiber with ultra-high liquid absorption properties

Composite medical dressings are made by combining different materials to achieve functions that cannot be realized by a single material, making it an important research direction for medical dressings. This study utilized the unique grooved structure of lotus stem fibers, and the functionality provided by different preparation processes for each layer of material to prepare a medical dressing that can achieve super-strong liquid absorption and storage effects. The prepared materials were characterized and analyzed through liquid absorption performance tests, Fourier transform infrared spectroscopy and scanning electron microscopy. The results showed that the pore structure of modified chitosan hydrogel, the curled distribution of lotus stem fibers in the material, and the moisture-wicking structure contribute to improving the liquid absorption properties. The composite dressing prepared using the optimal process for each layer of material exhibited moisture absorption and retention rates of 591.34% and 87.99%, respectively, demonstrating excellent liquid absorption properties. The antibacterial properties of the composite dressing were also tested against two common bacteria, and the dressing showed good antibacterial performance. The results indicated that the self-assembled composite medical dressing made from lotus stem fibers meets the preparation requirements, and has good application prospects for use in medical dressings.

Multi-scale moisture diffusion modeling and analysis of carbon/Kevlar-fiber hybrid composite laminates under the hygrothermal aging environment

Multi-scale moisture diffusion modeling and analysis of carbon/Kevlar-fiber hybrid composite laminates under the hygrothermal aging environment

Mechanical Characterization of Sisal Fiber Reinforced PP Composite Panels

ABSTRACT This study investigates the mechanical properties of single and double-layer woven sisal mat-reinforced PP composite panels. Sisal fibers were extracted using the manual decortication method, resulting in fibers with a density of 1.43 g/cm3 and a diameter ranging from 0.4 mm to 0.6 mm. To improve the bonding between the sisal fibers and the matrix, the fibers were hand-spun into yarn and woven into mats. The study focuses on the unique material combination and the use of sisal as a natural fiber reinforcement. The 18 mm thick panels were tested for water absorption following ASTM D570, compression strength, and tensile strength following ASTM D3039 using the UTES-100 High Precision universal strength tester machine. Composite panels with single layers of 10% and 15% woven fabric mat, loaded with 8 kg and 10 kg, exhibited compressive strengths of 11.6KN and 12.5KN, respectively. Panels reinforced with two layers of 20% and 30% sisal woven fabric mat, loaded with 8 kg and 10 kg, had compression strengths of 12.2KN and 12.5KN, respectively. Moreover, composite samples with 15% single layer and 30% double-layer sisal woven fabric mat demonstrated a equal compression strength of 12.5KN, falling within the range recommended by ISO13006:2012. The tensile strength of 16.99MPa, although slightly below the recommended ISO13006 value of 20MPa for commercial-grade panels, indicates promising results. The study’s findings suggest that higher fiber content and additional reinforcement layers lead to increased compression and tensile strength. Furthermore, the moisture absorption rate of the developed composite panels was significantly lower than the 0.5% water absorption rate authorized by the American National Standard Institute.

Impact of Calcined Natural Clinoptilolite Zeolite on Hydration Kinetics and Shrinkage of Cementitious Materials

Abstract Previous literature has provided contradictory results, so we present the current investigation to provide additional information to assess the suitability of using soak calcination as a pretreatment method to increase the performance of calcined zeolite when used as the supplementary cementitious material. In this study, natural clinoptilolite zeolite was calcined for three hours at 200°C, 400°C, 600°C, 800°C, and 1,000°C, and the effects of calcination on different physical and chemical properties were observed using a range of experimental tests. The impacts of calcined zeolite were investigated in the hydrated system with the replacement of portland cement up to 20 % by mass on hydration kinetics (i.e., heat of hydration, setting time, chemical shrinkage, degree of hydration), drying shrinkage, and compressive strength. Results revealed that calcination minorly decreased the crystallinity, particle size, and peak pore size of the zeolite, leading to a slightly increased external specific surface area, whereas it increased the rate of moisture absorption and pH of zeolite particles. In the hydrated cementitious system, calcined zeolite reduced the workability and heat of hydration and retarded the initial setting time. The calcined zeolite particles absorbed a part of the water from the fresh mixture and expanded volumetrically, which led to a negative volume of chemical shrinkage up to the final setting time and increased the drying shrinkage. As the dosages of calcined zeolite increased, the compressive strength substantially decreased because of the lower degree of hydration. Overall, soak calcination pretreatment decreased the reactivity of clinoptilolite zeolite particles and impacted the performance of calcined zeolite in the blended system.

천연섬유 열가소성 복합재료 제조 및 특성 연구

In this study, a natural fiber thermoplastic composite material was prepared by applying the natural fibers jute and kenaf as reinforcement materials and polypropylene (PP) and high-density polyethylene (HDPE), which are thermoplastic resins, as matrix materials. The natural fibers were surface-treated to activate the interface between them and the thermoplastic resins. Differential scanning calorimetry analysis of the thermoplastic resins was performed to apply the hot-pressing process, and changes in hot-pressing process conditions were observed. The tensile and bending strengths as well as moisture absorption rate of the composite materials to which jute and kenaf were applied were compared and analyzed to confirm the possibility of replacing the glass fiber composite with the natural fiber composite for use as a small-ship material. In addition, for application to ship decks, a sandwich-structured composite material was manufactured and analyzed by applying polyvinyl chloride foam to the natural fiber composite material.

Damage and failure mechanisms of carbon fiber reinforced composite thin-walled bushings under hygrothermal-mechanical loadings

Damage and failure mechanisms of carbon fiber reinforced composite thin-walled bushings under hygrothermal-mechanical loadings

Effect of hygroscopicity of typical powder solid wastes on their radon exhalation characteristics

The characteristics of radon exhalation in the hygroscopic properties of powder solid wastes are immensely significant for environmental safety and their transportation, storage, and landfill. This study detected the radon concentration of superfine cement and five kinds of powder solid waste: fly ash, silica fume, coal gangue, S95 mineral powder, and molybdenum tailing powder, at different hygroscopic times for 1-5d under 95% relative humidity. Additionally, the influence of particle size and porosity of solid waste on radon exhalation characteristics was analyzed using a laser particle size analyzer and nitrogen adsorption technology. The results show that the radon exhalation rate of the solid waste was at a low level in dry conditions. Although the presence of water due to the increased moisture absorption rate inhibited the radon exhalation to a certain extent, it was higher than that in dry conditions. The reciprocal of the moisture absorption rate had a strong linear relationship with the ratio between the radon exhalation rate after hygroscopy and radon exhalation rate from dry materials. The pore structure has a significant effect on the exhalation rate of radon, and the macropores inhibits the exhalation rate of radon. The results of this study have guiding significance for the reuse of solid waste and the prevention of radiation risk of radon exhalation during transportation.

Research on technological parameters affecting the quality of adhesive joints in casting model assemblies and assessment of their operational properties in liquid and humid environments

Modern casting model kits, often created using adhesive technologies, can experience deformations leading to warping and even destruction. This can occur due to differences in thermal expansion and moisture absorption rates between the material and the adhesive. The study evaluated the behavior of the adhesive joint in model kit elements under operational conditions in liquid and humid environments, assessing the hardness and strength of the joint. The analysis revealed a correlation between the density of the plastic and the quality of the adhesive joint.

Influence of humid and thermal environment on flexural properties of CFRP reinforced foam sandwich structures

Abstract The influence of the moisture and heat environment on the bending properties of CFRP laminates and CFRP reinforced foam sandwich structures was studied by mass change and three-point bending test. The results show that the saturation moisture absorption rate of CFRP laminates is low, only 0.62%. The CFRP reinforced foam sandwich structure exhibits a saturation moisture absorption rate of 1.48%. Humidity and heat have little effect on the bending modulus of CFRP laminates but have some effect on the bending strength, which decreases by 13.23% compared with normal temperature and dry conditions. The flexural strength and average energy absorption of CFRP reinforced foam sandwich structure decreased by 11.5% and 5.56% under hot and humid environments. The flexural fracture of the CFRP foam sandwich structure is smooth under normal temperatures and dry conditions. Many fibers are pulled out, and the resin falls off, obviously under hot and humid environments. The stratification of CFRP panels and foam cores in hot and humid environments is more obvious than in dry conditions at normal temperatures.