Large Number Of Pores Research Articles

Study of the Gap Parameters of Cement Mortar Specimens Based on X-ray Tomography

Concrete is one of the most widely used structural materials next to steel. This justifies a detailed study of the material structure to understand the influence of the production parameters on the properties of the concrete. The pore structure of concretes has a major influence on their practical use, as it impacts their resistance to environmental degradation (e.g., frost resistance). In the present study, I have investigated concrete and cement mortar specimens with different water-cement ratios using micro-CT (or micro X-ray tomography) to determine the pore structure and the pore gap parameters of the specimens. It can be concluded that with an increasing water-cement ratio the overall porosity of the samples and the number of large pores (1 mm3) show a decreasing trend, in contrast, the gap parameter shows an enhancing trend. It can also be concluded that any pore-forming additives cause significant changes in the structure.

The Application of Computed Tomography to Study the Soil Porosity of Mountain Red Earth

Mountain red soil, as a special type of soil in the South, has received widespread attention for its soil erosion problems. Its pore structure restricts water infiltration, thereby affecting the occurrence and development of soil erosion. In order to systematically obtain the distribution characteristics of the pore structure within the surface mountain red soil, this paper uses non-destructive CT detection technology to scan the soil column samples taken from the typical mountain red soil distribution area in Chenggong District, Kunming City, Yunnan Province. Image processing technology is applied to CT slices, and ImageJ (1.46r) software is used to obtain the distribution characteristics of pores within the soil column, including pore sizes and the number of pores at each depth, the proportion of pore area, roundness, and box-counting dimension. The results show that with the increase in depth, the proportion of pore area decreases linearly from the maximum value of 52.25% at the top to the minimum value of 2.02% at the bottom; the roundness of pores fluctuates between 0.8 and 0.9, overall increasing; the total number of pores generally first increases then decreases, and small pores are predominant, with the least number of large pores in the topsoil layer; the box-counting dimension shows a gradual linear decrease, with a maximum value of 1.7980 and a minimum value of 0.9878. The number of pores affects both roundness and the box-counting dimension, and the proportion of pore area also affects the box-counting dimension. There is a negative correlation between roundness and the box-counting dimension. The 3D visualization reconstruction of pores shows that most are interconnected, with the pore size significantly reducing with increasing depth. The quantitative analysis of parameters and 3D visualization reveal, to some extent, the impact of pore structure on the occurrence and development of soil erosion in mountain red soil. These research findings form the foundation for studying soil erosion in this region and provide a basis for systematically understanding its processes and mechanisms.

Enhanced photocatalytic activity of Z-scheme BiVO4 heterophase junction via giant built-in electric field

Built-in electric field (IEF) can improve photocatalytic efficiency by promoting charge separation and transfer. Herein, a Z-scheme BiVO4 heterophase junction with giant IEF was successfully constructed. By changing the pH value of the precursor solution, the ratio of monoclinic octahedral BiVO4 (m-BVO) to tetragonal microsphere BiVO4 (t-BVO) is regulated to form a heterophase junction (mt-BVO), so as to regulate the IEF intensity. When pH = 0.5, a large number of pores were formed at the interface of the two forms in mt-BVO-35%m, so it has a larger specific surface area. mt-BVO-35%m has optimal photocatalytic tetracycline degradation activity. Under visible light irradiation, its reaction rate constant k is shown to be 3 times higher than that of pure m-BVO, and the TOC removal rate has increased from 12 % to 36 %. Through characterization, it can be proved that the IEF strength of mt-BVO-35%m is 11.86 times that of m-BVO. The significantly improved activity is mainly attributed to the presence of a giant IEF between m-BVO and t-BVO. The IEF drives the photogenerated electrons to transfer from the CB of t-BiVO4 to the VB of m-BiVO4, which greatly enhances the separation and transfer of photogenerated charge carriers. Moreover, a mechanism of Z-scheme charges transfer pathway in the mt-BVO-35%m heterophase junction was also revealed.

Adjustable double cation vacancies MnSex/FeSex p-n heterojunction catalysts on improving multifunctional photocatalytic and photoelectrochemical performance

MnSex is a type of p-type semiconductor that combines with n-type FeSex in a one-step hydrothermal method to form a MnSex/FeSex p-n type heterojunction. The heterostructures showed good photocatalytic performance. The photocatalytic degradation rate constant of MFS3 was 0.01114 min−1, while that of MnSex was 0.00213 min−1. The photocatalytic degradation activity of MFS3 was 423 % higher than that of MnSex. Afterwards, the MnSex/FeSex catalyst was further soaked in ethylenediaminetetraacetic acid (EDTA) to form metal vacancies through metal complexation. A large number of pores can be seen in the SEM image of MFS3v catalyst, and Mn and Fe bimetallic vacancies can be seen in the TEM results. The signal of the electron paramagnetic spectrum is significantly enhanced, with a significant shift in its g value. The above results confirm the formation of Mn and Fe bimetallic vacancies in the catalyst. The two-hole heterojunction catalyst significantly improves its photochemical activity, and the photocurrent density of MFS3v at 0 V vs. RHE is −2.438 mA/cm2, 18.2 and 2.5 times that of the original MnSex and MnSex/FeSex heterojunction, respectively. Tests have confirmed that this double vacancy can increase the active sites and enhance the photoelectrochemical hydrogen production ability. This study proposes a method that combines heterojunctions and vacancies to achieve multifunctional catalysts.

Confined graphitization induced pore generation for designing novel potassium-ion battery carbon anode with large capacity and ultra-long cycle life

Carbon is one of the most superior anode materials for K-ion batteries but faces the challenges of low capacity and poor cycle stability. In general, the K+ storage capacity depends on the graphitized carbon layers and defective structure, while the cycle stability can be enhanced by constructing sufficient nanospace to alleviate the volume expansion during the potassiation/depotassiation process. However, the above structures are difficult to integrate into a single carbon material because graphitization often eliminates defects and pore structures. In this work, we find that ultrathin carbon sheets have a confined graphitization effect, which allows the carbon layer to orientationally arrange at a low heating-treatment temperature. More importantly, this orientational arrangement causes size shrinkage, inducing structural splitting on the faces of the carbon sheets and producing abundant defects and a large number of pores. Based on this, we obtain a novel carbon with highly graphitized, large-surface-area and defect-rich frameworks, which gives a K+ storage capacity of 358 mAh g−1, and after 4000 cycles, this carbon shows no obvious capacity degradation, with a capacity retention rate of nearly 100 %. Carbon anodes of K-ion batteries with such large capacity and long cycling life have rarely been achieved before.

Investigation of the effect of relative humidity on micro lime consolidation of degraded earthen structures

Micro lime, hydrated lime (Ca (OH)2) with particle sizes of 1-3μ dispersed in isopropanol, can be used to reinforce deteriorated earthen structures. The consolidation effect depends on the amount of moisture present in the structure or in the ambient air. This study investigates the influence of different levels of relative humidity (RH) on the consolidation effect of micro lime on earthen structures, the chemical processes responsible for the consolidation and the physical changes to the structure. The aim is to gain a deeper understanding of the underlying chemical reactions and to identify a potential limit to the applicability of this consolidation method in low RH environments. The fact that many of these sites are located in arid climates greatly influences the practical application of micro lime in the conservation of historical earthen structures. To characterize the consolidation effect of micro lime, unconfined compressive strength and exposure to wet and dry cycles were used. The properties of the reaction products and the bonding between soil particles and micro lime were investigated using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). At RH levels of 25%, 45%, 65% and 90%, the unconfined compressive strength (UCS) and the modulus of deformation at 50% strength (E50) of the micro lime-reinforced specimens demonstrated an increase with humidity. This led to a significant improvement in their ability to resist the effects of dry–wet cycles. Results from thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) indicate that micro lime interacts with the soil matrix via carbonation, with the reaction rate increasing with humidity. At 25% RH, vaterite was produced and residual free lime was observed, whereas at humidity levels of 45% and above, the reaction yielded vaterite and aragonite. The lime treatment did not significantly alter the pore structure of the soil specimens. The total porosity of the specimens was only slightly reduced, with the main effect of the lime treatment being a reduction in the number of large pores.

Utilizing Date Palm Leaf Biochar for Simultaneous Adsorption of Pb(II) and Iodine from Aqueous Solutions

This study addresses the environmental and health hazards posed by Pb(II) and iodine, two significant contaminants. The objective was to explore the adsorption of these substances from aqueous solutions using biochar derived from the leaf midribs of the date palm through a slow pyrolysis process. The pyrolysis was conducted in two stages within a vacuum furnace: initially at 300 °C for 1 h followed by overnight cooling, and then at 600 °C with a similar cooling process. The resulting biochar was characterized for its microstructural features and functional groups using scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. It exhibited a porous structure with large numbers of pores (20 to 50 μm in size) and functional groups including O-H, C-H, and C=C, which are integral to its adsorption capabilities. For the adsorption studies, a 100 ppm Pb(II) ion solution was treated with varying amounts of biochar (20, 40, 60, and 80 mg) for 24 h. In parallel, iodine adsorption was tested, with biochar quantities ranging from 0.1 to 0.4 g/50 mL. Both treatments were followed by filtration and analysis using atomic absorption spectroscopy to determine the remaining concentrations of Pb(II) and iodine. The study also explored the effect of varying incubation periods (up to 30 h) on iodine adsorption. The results were significant; 100% adsorption of Pb(II) was achieved with the addition of 60 mg of biochar per 10 mL of solution. In contrast, for iodine, a maximum adsorption of 39.7% was observed with 30 mg or 40 mg of biochar per 50 mL. These findings demonstrate the potential of date palm-derived biochar as an effective and sustainable material for the removal of Pb(II) and iodine from contaminated water, offering valuable insights for environmental remediation strategies.

Understanding Diffusion in a Single-Metal Organic Framework Crystal Used for Sensing Applications.

Metal-organic frameworks (MOFs) stand out as remarkable materials renowned for their exceptionally high surface area and large number of pores, making them invaluable for diverse sensing applications including gas, biomedical, chemical, and optical sensing. Traditional methods of molecule infusion and release often involve a large number of crystals with varying shapes and sizes, leading to averaged outcomes across a heterogeneous crystal population. In this study, we present continuous monitoring of the infusion and release dynamics of model drug molecules, specifically vitamin B12, within individual Tb-mesoMOF crystals. Our findings underscore the critical influence of crystal size and shape on the infusion and diffusion processes and corresponding color change, underscoring the necessity to account for these factors in the design of large-scale systems. Leveraging optical microscopy, we employed a histogram-based algorithm for image processing, enabling automated tracking of diffusion phenomena. This investigation offers crucial insights into the dynamics of these processes, laying the groundwork for optimizing parameters in future sensing systems.

Analysis and Characterization of Micro–Nano Pores in Coal Reservoirs of Different Coal Ranks

Coalbed methane represents a promising source of clean and efficient unconventional energy. The intricate network of micro–nano pores within coal serves as the primary adsorption space for gas, contributing to the complexity of gas migration channels. In this study, based on the box-counting method, three coal samples representing low, medium, and high ranks were subjected to high-precision micro-CT scanning and nano-CT scanning to generate three-dimensional (3D) pore network models using Avizo visualization software. This facilitated the accurate and quantitative characterization of the micro–nano pore structures within coal reservoirs. The results indicated that the face rate distribution range of each sample was large, indicating relatively strong heterogeneity in each sample. The volume fractal dimension of each sample, determined through micro–nano-CT scanning, was around 2.5, while the surface fractal dimension exhibited oscillatory characteristics with moderate uniformity. The pore equivalent radius and throat equivalent radius distributions were unimodal across all the samples, with the micro-CT scanning revealing a concentration primarily within the range of 100–400 μm for the pore equivalent radius and within 200 μm for the throat equivalent radius. Conversely, the nano-CT scanning exhibited concentrations primarily within the range of 500–2500 nm for the pore equivalent radius and within 2000 nm for the throat equivalent radius. The analysis of the 3D reconstruction structures indicated that the middle-rank coal exhibited more developed large–medium pores compared with the low-rank and high-rank coal, while the low-rank and high-rank coal exhibited relatively more micro–small pores. Furthermore, the low-rank coal exhibited the fewest number of pores but the largest average pore equivalent radius and throat radius. Additionally, the middle–high-rank coal exhibited a relatively larger number of pores. Despite the complex topological structures observed in each sample, a significant proportion indicated a coordination number of 0–20, indicating excellent connectivity within the coal samples. This study is conducive to the optimization of coalbed methane surface development blocks and the formulation of reasonable development plans.

Construction and Evaluation of Paclitaxel Mn-Doped Dendritic Mesoporous Silica Coated with N-Succinyl Chitosan

Mesoporous silica, as a drug carrier, has become the new research focus in the field of nanodrug delivery system in recent years. In this study, Mn-doped mesoporous silicas are synthesized by template and in-situ doping method and physically characterized. The drug-loading performance of silica and its impact on drug release are studied. The Mn-doped mesoporous silicas show dendritic morphology (MDMS) with a loose wrinkle structure on the surface and a large number of pores. MDMS is used as a carrier to solve the problem of low water solubility of paclitaxel. In order to avoid leakage during drug transportation, the surface of Mn-doped mesoporous silica loaded with paclitaxel is coated with N-succinyl chitosan to construct a new type of nanodrug delivery system (MDMS-PTX-NSC). Compared to MDMS, MDMS-PTX-NSC shows an increase in particle size and smooth surface. The dissolution characteristics of manganese ions and swelling behavior of N-succinyl chitosan make MDMS-PTX-NSC delivery system exhibit a good pH-responsive release. And MDMS-PTX-NSC release curve can be well fitted by Ritger-Peppas equation. The cytotoxicity test shows that the MDMS-PTX-NSC has significant biocompatibility and enhanced cytotoxicity, which reveals that the MDMS-PTX-NSC is a promising nanodrug delivery system.

Research on Salt Drainage Efficiency and Anti-Siltation Effect of Subsurface Drainage Pipes with Different Filter Materials

Subsurface pipes covered with geotextiles and filters are essential for preventing clogging and ensuring efficient drainage. To address low salt discharge efficiency due to subsurface drainage pipes (SDPs) clogging easily, sand gravel, straw, and combined sand gravel–straw were set above SDPs, respectively, within a setting of uniform geotextiles. The influences of different filter materials on the drainage efficiency and salt discharge effect of the SDPs, as well as the effects of different filter materials on the salt drainage efficiency and anti-siltation effect of the SDPs were studied by performing simulation experiments in a laboratory. The results confirmed the following: (1) The salt removal rates of the SDPs externally wrapped with materials exceeded 95%. The subsurface pipe treated with the sand gravel filter material had the highest desalting rate (93.69%) and soil profiles with total salt contents that were 17.7% and 20.5% lower than those treated with the straw and combined sand gravel–straw materials, respectively. (2) The soil salinity of the sand gravel filter material around the SDPs was between 1.57 and 3.6 g/kg, and the drainage rate (R) was 0.97, so its salt-leaching effect was the best. (3) The sand gravel filter material increased the characteristic particle size of the soil above the SDP by 8.4%. It could effectively intercept coarse particles, release fine particles, and facilitate the formation of a highly permeable soil skeleton consisting of coarse particles, such as sand particles surrounding the soil. (4) The use of the straw filter material produced dense filter cake layers on the upstream surfaces of the geotextiles. When the sand gravel and combined sand gravel–straw filter materials were used, soil particles remained in the geotextile fiber structure, and a large number of pores were still retained. Therefore, the sand gravel filter material was the most suitable for the treatment of Yinbei saline–alkali soil in Ningxia Hui Autonomous Region.

Microstructure and mechanical properties of WC-12Co cemented carbide fabricated by laser powder bed fusion on a WC-20Co cemented carbide substrate

In this study, WC-12Co cemented carbides were prepared by laser powder bed fusion (LPBF) on a WC-20Co substrate. The effects of the scanning speed and the substrate on the microstructure, mechanical properties and wear characteristics of the WC-12Co cemented carbide were investigated. The results showed that an alternating distribution of coarse and fine WC grains is observed in the LPBF-prepared WC-12Co cemented carbides. As the laser scanning speed decreases or the laser energy density increases, the WC phase gradually decomposes, accompanied by the loss of C and the formation of ƞ phases. WC-12Co cemented carbides produced at a lower scanning speed exhibit a higher density of thermal cracks, while those produced at a higher scanning speed have a larger number of pores. As the laser scanning speed increases, the transverse rupture strength (TRS) first increases to a maximum value of 823.13 MPa and then decreases. The variation of TRS is mainly attributed to the evolution of the brittle ƞ-phase and metallurgical defects. For WC-12Co cemented carbides formed at low scanning speeds, the brittle η-phase may fracture and cut through the matrix during the friction process, leading to an increase in coefficient of friction (COF) and wear mass loss. For samples formed at high scanning speeds, the formation and detachment of the shear layer could accelerate the friction process and undermine the wear resistance of the WC-12Co cemented carbide. Therefore, the sample prepared at the scanning speed of 400 mm/s shows the best wear performance.

New insights into the stress rupture life enhancement mechanisms of a nickel-based superalloy

In this paper, the effects of hot isostatic pressing (HIP) and heat treatment (HT) on the stress rupture properties of nickel-based superalloy K417G were investigated. Scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) were employed to analyze the microstructure, fracture morphology, determination of crack source and dislocation evolution after stress rupture fracture. The results indicate that, HIP specimens demonstrate a 19.5% reduction in stress rupture life compared to as-cast specimens, whereas HIP + HT specimens exhibit a 41% increase in stress rupture life, reaching a value of 63.04 h. The fracture mechanism of the samples under different heat treatment conditions is different. There are a large number of pores in the as-cast specimen, which leads to the initiation and propagation of cracks and eventually result in fracture. The pores in the HIP specimen are almost eliminated. However, the coarsening and uneven distribution of γ′ phase led to the weakening of the hindrance to dislocation movement. Additionally, the increase in elongated carbides at grain boundaries accelerates crack initiation and propagation. Under HIP and HT, the cubic γ′ phase is uniformly precipitated, which effectively hinders the movement of dislocation lines. Granular M23C6 carbides precipitate at grain boundaries, acting as pinning points to retard grain boundary sliding and crack propagation, thus improving the stress rupture life.

Mechanical and microstructural properties of one-part geopolymer-solidified soil attacked by Na2SO4

In the construction of traffic engineering, a large amount of waste soils was generated. These soils have poor engineering properties, cannot be used as subgrade fill, so they were solidified treatment, commonly used cement curing agent have adverse effects on the environment. One-part geopolymer (OPG), as a green and new type of soil stabilizer, not only provides a new idea for the solidification of engineering waste, but also offers an effective way for the disposal of industrial solid waste, and reduces the consumption of cement. In order to evaluate the durability of geopolymer solidified soil, in this paper, with fly ash (FA) and ground granulated blast furnace slag (GGBS) as raw materials, solid NaOH and Na2SiO3 as solid alkali-activator to prepare OPG, which was used as a solidifier to solidify the waste dredged silt to produce one-part geopolymer-solidified soil (OPGSS). The variation patterns of mass, unconfined compression strength (UCS) and elasticity modulus of OPGSS with attack time under 0%, 5% and 10% Na2SO4 solutions were investigated. The changes in the phase composition, micro-morphology and pore size distribution of OPGSS were characterized by XRD, SEM-EDS and nuclear magnetic resonance (NMR). The results showed that: Under both 5% and 10% Na2SO4 solutions, the UCS of OPGSS decreased in two stages with attack time, and the number of large pores and total pores of OPGSS increased in two stages. The inflection points appeared on day 8 under 5% Na2SO4 solution; the inflection points appeared on day 5 under 10% Na2SO4 solution. This was mainly due to the expansion of corrosion products formed by OPGSS under Na2SO4 attack, which destroyed the microstructure of OPGSS and led to a reduction in the UCS of the OPGSS.

Influence of energy density on the microstructure and property regulation of additive manufactured pure nickel

In this work, laser powder bed fusion (LPBF) technology was used to fabricate pure nickel components, and the densification behavior and microstructure of pure nickel with different energy densities were investigated. The results indicate that for LPBF-fabricated pure nickel components, the relative density reaches a peak of 98.76% at an energy density of 101 J/mm3. With the increase of energy density, a large number of pores appear inside the grains, and the grains grow epitaxially along the building direction within multiple molten pools, pores gradually disappear after undergoing remelting at the edges of the melting tracks. Among these, competitive inward growth of columnar crystals may be the main cause of dislocations and new grain generation. The grains are primarily distributed along the Ni (111) or Ni (110) orientations, and with the increase of energy density, the grains with these two orientations increase. The surface energy follows the sequence of Ni (220) > Ni (200) > Ni (111). Due to the stacking of the <101> oriented main layer and the <001> oriented sub-layer in the building direction, the sample with higher energy density exhibits a strong Ni {110} texture, accompanied by increased tensile properties.

Acoustic Fractional Propagation in Terms of Porous Xerogel and Fractal Parameters.

This article portrays solid xerogel-type materials, based on chitosan, TEGylated phenothiazine, and TEG (tri-ethylene glycol), dotted with a large number of pores, that are effectively represented in their constitutive structure. They were assumed to be fractal geometrical entities and adjudged as such. The acoustic fractional propagation equation in a fractal porous media was successfully applied and solved with the help of Bessel functions. In addition, the fractal character was demonstrated by the produced fractal analysis, and it has been proven on the evaluated scanning electron microscopy (SEM) pictures of porous xerogel compounds. The fractal parameters (more precisely, the fractal dimension), the lacunarity, and the Hurst index were calculated with great accuracy.

Effect of laser power on the microstructure and corrosion resistance of laser cladding Mo2NiB2 coatings

In this study, Mo2NiB2 coatings were prepared by the laser cladding technique and the relationship between coating microstructure and corrosion resistance with cladding power was analyzed. The results showed that Mo2NiB2 was reactively generated in all coatings while Mo2FeB2 and (Fe, Ni) were also present in the coatings due to dilution of the substrate. There was a good metallurgical bond between the coating and the substrate. The white cermet phase and black Fe-rich phase alternated within the coatings. As observed from the surface, the ceramic phase spreads out in a flattened shape and the black Fe-rich phase was present in a large number of pores. Due to the overdilution of the substrate, the volume of the ceramic phase decreased at a power of 800 W and the Fe content within the coating increased. The corrosion resistance of the coatings increased as the laser power increased from 500 to 700 W. Then the corrosion resistance of the coatings decreased at 800 W due to the excess Fe content and the decrease in the relative content of Mo2NiB2 and (Fe, Ni). Mo2NiB2 coating prepared at 700 W has the best corrosion resistance.

Effects of sintering additives on dielectric breakdown strength of sintered reaction-bonded silicon nitride

We prepared sintered reaction-bonded silicon nitride (Si3N4) by using various lanthanide oxides and magnesia for sintering additives and evaluated their effects on the microstructure and dielectric breakdown strength (DBS). Both the microstructure and DBS varied by the types of the sintering additives, and artificial intelligence (AI) based determination was conducted for the DBS to separate the effect of microstructural factors from that of sintering additives. The results indicated that the DBS values varied mainly by the former effect. The microstructures of Si3N4 with Eu2O3 and La2O3 contained a large number of pores, leading to lowered DBS; on the contrary, those with Tm2O3 and Y2O3 possessed dense microstructures with large-elongated grains, showing higher DBS. On the other hand, the Si3N4 with Yb2O3 showed lower DBS than what AI-determined from the microstructures because the additive forms grain boundary phase with a low electrical resistance.

A lead-free flexible polymer/ceramic based nanocomposites thin film for electronic application

The polymer composite Bismuth Titanate based lead-free binary system Nylon-11/0.75Bi0.5Na0.5TiO3-0.25SrTiO3 (N11/BNTST) has been developed using the solution casting method in different ratio for advanced energy system. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were used to confirm the structure. XRD pattern of all samples shows the N11 and rhombohedral phase of BNT-ST with the presence of both phases for the composite. The surface microstructure of a nanocomposites film with a 70:30 N11:BNT-ST composition reveals homogenous BNT-ST nanoparticle dispersion in Nylon-11 matrix with negligible holes. However, compositions with a larger percentage of BNT-ST show agglomeration with a large number of pores, which lowers the dielectric constant and increases dielectric loss. At room temperature, the electrical characteristics of the produced N11/BNT-ST composite are examined periodically. The dielectric behavior of the materials exhibit a decrease in dielectric constant as well as loss with increasing frequency. The experimental data of the N11/BNTST, comparing the pure N11 polymer film to composite, the dielectric characteristics have significantly improved. The maximum dielectric response has been observed for 70N11-30BNTST composition. So, N11/BNTST composite has been shown to be a viable option for applications requiring electronic capacitive energy storage.

The relationship between pore structure and strength of aeolian sand concrete under low temperature

To examine the relationship between microscopic parameters and compressive strength of aeolian sand concrete (ASC) at low temperatures, the compressive strength of ASC at different temperatures is predicted by factors such as the pore structure parameters and the ambient temperature. The experiments used 100 % replacement of river sand (RS) with aeolian sand (AS) to prepare fully ASC, and regular concrete with the same water-cement ratio as the control group. The experiment used nuclear magnetic resonance (NMR) technology and grey correlation analysis method to analyze the microscopic parameters and compressive strength of concrete specimens with three curing ages of 7d, 28d, and 60d at temperatures of 20 °C, 0 °C, −5 °C, −10 °C, −15 °C, and −20 °C. It was shown that the agglomeration between the fine particles during the mixing process results in a large number of pores in the interior of the ASC, resulting in a larger porosity compared to ordinary concrete. As a result, its compressive strength was lower than that of ordinary concrete, and the loose and porous internal structure provides room for the filling of more ice crystals. Therefore, the increase in compressive strength of ASC at different curing ages in an environment of −20 °C was greater than that of ordinary concrete. Among them, at-20 °C, the compressive strength of ASC with curing ages of 7d, 28d and 60d increased by 6.31 %, 3.59 % and 3.97 % respectively compared with ordinary concrete. Finally, a predictive model between parameters such as temperature, porosity, mean pore size distribution and gel content and compressive strength was developed, which was highly accurate.