Volume Average Particle Size Research Articles

Research on coal crushing behavior under supercritical CO2 transient high-pressure fracturing

CO2 fracturing enhances gas permeability by creating a complex network of fractures in coal seams. Crushing serves as the foundation of fracture development, and studying the coal crushing behavior under supercritical CO2 transient high-pressure fracturing is of great significance to understand fracture evolution and guide precise fracturing. This study utilized a self-built experimental platform for supercritical CO2 transient high-pressure fracturing to obtain fractured coals at different energy levels. Based on multifractal theory, the relationship between fracturing energy and crushing behavior was studied by laser particle analysis and scanning electron microscopy. The results showed that the volume average particle size (D4,3), and the particle sizes at which the cumulative particle size distribution reached 50% (D50), and 90% (D90) decreased significantly with the increase of fracturing energy. The converted diameter and the crushing work ratio exhibited an exponential relationship with the fracturing energy. The larger the fracturing energy, the smaller the values of the multifractal generalized dimension spectrum parameters (D0, D1, and ΔD(q)), the larger the values of the multifractal singular spectrum width (Δα (q)), and the denser and more even the particle size distribution of fractured coal. The multifractal parameters and shape coefficients exhibited phased change during the fracturing process. The coal particles progressed from an initial stage with numerous microcracks and fissures to a honeycomb structures with small pores. After the disintegration of the honeycomb structures, agglomerated ultrafine particles were formed. The findings provide a theoretical reference for optimizing the selection of fracturing parameters.

Preparation and investigation of two-component silica-modified hydrophobic layer for minimizing retention loss of reversed-phase chromatographic columns using fully aqueous mobile phases

Chromatographers often employ fully aqueous mobile phases to retain highly polar compounds in reversed-phase liquid chromatography (RPLC). However, when the flow rate is interrupted, either accidentally or intentionally, a substantial loss in retention occurs due to the spontaneous dewetting of water from the hydrophobic surface of conventional RPLC-C18 particles. Previous studies have shown that maintaining a low C18 surface coverage (approximately 1.5 μmol/m2) can mitigate water dewetting by increasing chain disorder, facilitating the intercalation of water clusters between the C18-bonded chains, and keeping the mesopores wetted. In this research, we explore the potential and additional benefits of using two-component surface bonding materials (C8/C18 and PhenylHexyl (PhHx)/C18) at a constant and low total surface coverage of 1.51 ± 0.15 μmol/m2. We synthesized seven one- and two-component modified silica particles with a volume average particle size of 5.22 μm and an average mesopore size of 104 Å. The surface coverage was increased from 0 to 0.54, 1.00, and to 1.66 μmol2 for C8 chains and from 0 to 0.52, 0.70, and to 1.65 μmol2 for PhHx ligands. To prevent interactions between water and any unreacted silanols, all seven derivatized particles were heavily endcapped with trimethylsilane (TMS) reagent. The fraction of the surface area remaining in contact with water was determined by measuring the retention times of weakly (thiourea) and strongly (thymine) retained compounds at intervals of 1, 2, 4, 8, 16, 32, and 64 minutes following the cessation of flow. Two distinct column temperatures, 24°C and 60°C, were employed in the experiments. Retention losses were found to be minimized in the presence of a small quantity of C8 chains (less than 40% of the total surface coverage). Additionally, it is essential to consider substantial fractions of PhHx chains, as long as the presence of the PhHx ligand does not significantly impact retention and selectivity. Combining mixed RPLC bondings with a low total surface coverage of approximately 1.5 μmol/m2 emerges as a viable solution for further minimizing retention loss in standard C18-bonded RPLC columns, particularly within the surface coverage range of 2.5-3.0 μmol/m2.

Effect of oil phase type and lutein loading on emulsifying properties and in vitro digestion of mandarin peel pectin emulsions

Oil phases with different chain lengths and saturations were used to make mandarin peel pectin (MPP) emulsions with and without lutein loading. The outcomes demonstrated that the emulsifying, digesting characteristics and lutein bioaccessibility of MPP emulsion were related to the addition of lutein and also oil phase species. After lutein addition, the apparent viscosity of MPP emulsions and interfacial tension were dramatically decreased. MPP emulsions made from medium-chain triglyceride (MCT) oil displayed higher absolute zeta potential, free fatty acid release, and lutein bioaccessibility, while those made from long-chain triglyceride (LCT) (palm oil, corn oil, and olive oil) had higher volume average particle size and interfacial tension. The findings offered a theoretical foundation for effective delivery and release of lutein by pectin emulsion.

Emulsifying properties, in vitro digestive characteristics, and β-carotene bioaccessibility of mandarin peel pectin emulsions prepared with different carrier oil phases

Mandarin peel pectin (MPP) emulsions were prepared with different oil phase loadings with or without β-carotene, and their emulsifying characteristics, digestive properties and β-carotene bioaccessibility were investigated. Results revealed that all MPP emulsions exhibited good loading efficiency for β-carotene, while their apparent viscosity and interfacial pressure (π) of MPP emulsions increased significantly after the addition of β-carotene. Emulsification of MPP emulsions as well as digestibility were significantly dependent on the kind of oil. MPP emulsions prepared with long-chain triglycerides (LCT) oil (soybean, corn, and olive oil) exhibited higher volume average particle size (D4,3), apparent viscosity, π values, and bioaccessibility of carotene compared to those prepared with medium-chain oils (MCT). MPP emulsions with LCT rich in monosaturated fatty acids (olive oil) had the highest β-carotene encapsulation efficiency, bioaccessibility, etc. than from other oils. This study provides a theoretical basis for the efficient encapsulation and high bioaccessibility of carotenoids with pectin emulsions.

Effects of high acyl gellan gum on the rheological properties, stability, and salt ion stress of sodium caseinate emulsion

Sodium caseinate (SC) is widely used as a biological macromolecular emulsifier in oil-in-water (O/W) emulsions. However, the SC-stabilized emulsions were unstable. High-acyl gellan gum (HA) is an anionic macromolecular polysaccharide that improves emulsion stability. This study aimed to investigate the effects of HA addition on the stability and rheological properties of SC-stabilized emulsions. Study results revealed that HA concentrations >0.1 % could increase Turbiscan stability, reduce the volume average particle size, and increase the zeta-potential absolute value of the SC-stabilized emulsions. In addition, HA increased the triple-phase contact angle of SC, transformed SC-stabilized emulsions into non-Newtonian fluids, and effectively inhibited the movement of emulsion droplets. The effect of 0.125 % HA concentration was the most effective, allowing SC-stabilized emulsions to maintain good kinetic stability over a 30-d period. NaCl destabilized SC-stabilized emulsions but had no significant effect on HA-SC emulsions. In summary, HA concentration had a significant effect on the stability of SC-stabilized emulsions. HA altered the rheological properties and reduced creaming and coalescence by forming a three-dimensional network structure, increasing the electrostatic repulsion of the emulsion and the adsorption capacity of SC at the oil-water interface, and thereby improving the stability of SC-stabilized emulsions during storage and in the presence of NaCl.

Dispersing silica fume in cementitious materials by silane copolymerized polycarboxylate Superplasticizer: On the role of dispersion effectiveness as a function of silane concentration

In this paper, a commonly used vinyl based silane coupling agent (SC), namely γ-methacryloxy propyl trimethoxyl silane (MAPTMS) was designed to co-polymerize with polycarboxylate superplasticizer (PCE) to increase the compatibility of PCE with silica fume (SF). The role of dispersion effectiveness as a function of silane concentration was systematically analyzed. It was found that at lower MAPTMS concentration, the prepared SC-PCE showed better SF dispersion capability than the control PCE with increasing MAPTMS concentration. The increased particle dispersion effectiveness was confirmed by minimized volume average particle size of SF by two orders of magnitude (from 27.507 μm to 0.275 μm), as well as a much slower SF particles settlement speed in a model cement solution. Increment of cement compressive strength reconfirmed the positive effect of SC-PCE on particle dispersion. When the mole substitution of AA by MAPTMS overran to 40%, however, SC-PCE behaved like polymeric silane silica sol and gelled as indicated by increase of viscosity overtime. The dispersion ability of SC-PCE ceased to be in effect. A maximum substitution ratio of MAPTMS was therefore need to be considered when designing a more effective SC-PCE for SF, as well as for other siliceous SCM.

Effects of Pretreatment on the Yield of Peanut Oil and Protein Extracted by Aqueous Enzymatic Extraction and the Characteristics of the Emulsion.

Effects of comminution on peanut particle size and yield of peanut oil and protein were analyzed. Additionally, the emulsion properties (surface protein concentration, particle size, and ξ-potential) were compared. Moreover, different demulsification methods were used to investigate the emulsion stability. Results showed that the yield of peanut oil and protein was highest (87.23% and 82.05%, respectively) after dry comminution for 72 s. Upon wet comminution for 120 s, the yields of peanut oil and protein were 89.91% and 84.70%, respectively, which were both significantly higher than that obtained after dry comminution (p < 0.05). The surface protein concentration and ξ-potential of emulsion made by dry comminution (DCE) were 7.02 mg/m2 and 12.08 mV, respectively, and those of emulsion made by wet comminution (WCE) were 10.71 mg/m2 and 15.25 mV, respectively, which were significantly higher than that of DCE (p < 0.05). The volume average particle size of DCE was 3.41 µm, which was significantly higher than that of WCE (3.18 µm, p < 0.05). Collectively, these results indicated that WCE was more stable than DCE. Further, the demulsification rate of DCE was significantly higher than that of WCE when treated by freeze-thawing, pH, papain, and phospholipase A2 (p < 0.05). Demulsification effect of Alcalase 2.4L was the best among these five demulsification methods treated, and the demulsification rate of DCE reached 92.77%, which was slightly higher than that of WCE (92.67%), further illustrating the higher stability of WCE.

A new view on improving the preparation efficiency of shear thickening fluid

In this paper, the relationship of rheological properties, particle size and particle size distribution of dispersed phase silica at different blending times during the preparation of STF was studied in detail. It is found that with the increase of blending time, the initial viscosity η0 of STF decreases, the critical shear rate γc increases, the maximum thickening viscosity ηm decreases, the thickening ratio decreases and the shear thickening effect of the system shows a weakening trend. On the other, the volume average particle size of silica decreases gradually and finally reaches a stable value. The particle size distribution changed from double-interval distribution to single-interval distribution. The variation of shear thickening properties with blending time was explained by combining Cluster and Jamming theory. It is considered that the preparation of STF can be completed when the suspension is transparent and has a uniform viscosity. It is believed that this will play an important role in improving the efficiency of STF preparation and will be of great help to realize industrialized production of STF in the future.

Effect of Production Factors on Particle Size of Silver Powder Produced through Water Atomization

Silver powder was prepared through water atomization at 1280℃ under the nitrogen atmosphere. As-prepared silver powder consisted of various particles with morphologies such as spherical, irregular and coarse and had high crystallinity. Relationship between the volume average particle size (D50) of silver powder and production factors was investigated. In this work, the production factors such as atomization pressure, angle, nozzle diameter, suction amount of air and water temperature were selected to verify the influence on D50. It was found that D50 decreased with decreasing atomization pressure, angle, nozzle diameter and water temperature. When the atomization pressure was 100 MPa, the uniform water stream was disturbed and then D50 became higher. On the other hand, it was confirmed that D50 decreased with increasing suction amount under reduced pressure. Crystallite size and crystallinity of silver powder increased with decreasing water temperature.

Relationship between physicochemical characteristics and in vitro digestibility of chestnut (Castanea mollissima) starch

The present study investigated the differences in starch and amylose content among six chestnut cultivars widely distributed in China, as well as the relationship between their physicochemical characteristics and in vitro digestibility. The cultivar and geographical distribution significantly influenced the characteristics of chestnut starch. The starch granule from all six cultivars was round or irregular polygonal in shape, with a particle size that varied from 1 to 20 μm. The amylose content ranged from 22.27 to 29.80% of starch, while the damaged starch was 3.44–11.94%. The volume average particle size of the chestnut starches from the six cultivars varied from 8.33 to 10.24 μm, and the median diameter ranged from 6.82 to 8.69 μm. The short-range order of the six chestnut starches exhibited no significant difference, but their X-ray patterns were different and their relative crystallinity ranged between 19.3 and 27.9%. The resistant starch accounts for 70.1–85.6% of chestnut starch, and was found to be positively correlated with the amylose content. The glycemic index was negatively correlated with the relative crystallinity, indicating that the crystalline structure of starch had a retardant effect on its digestibility.

Characterization of Silver Powder Produced through Water Atomization and RF Plasma Treatment

Silver powder was produced through water atomization with a pressure of 80 MPa and a flow rate of 220 L/min. Scanning electron microscopy analysis showed that as-prepared silver particles were aggregated and had various types of morphologies such as spherical, spheroidal and irregular. The volume average particle size of as-prepared silver powder was 7.7 μm at the drain rate of 0.024 kg/s. The particle size decreased with decreasing the drain rate. Powder X-ray diffraction revealed that the silver powder with a single phase and high crystallinity was formed. Surface treatment of silver powders classified to 5 μm was performed at 10,000°C by radio-frequency (RF) plasma under argon atmosphere. RF plasma treatment led to the formation of spherical particles from irregular particles. The crystallinity and crystallite of silver powder were increased by RF plasma treatment. X-ray photoelectron spectroscopy showed that the oxygen content in silver particles decreased from 500 ppm to 45 ppm. Thermomechanical analysis revealed that the shrinkage of silver powder reduced by the RF plasma treatment. It was clear that the particle characterization of silver powder was significantly modified by RF plasma treatment. The specific resistivity of silver paste sintered at 900°C exhibited 1.89×10-8 Ωm.

窒素雰囲気下での高圧水アトマイズ法による銀粉末の製造および電極特性

Silver powder was produced through water atomization at the high pressure of 80 MPa. Before the water atomization, silver was melted at 1330°C under nitrogen atmosphere. Scanning electron microscope observation showed that the as-prepared silver powder had various particles with morphologies such as spherical, irregular and coarse. The volume average particle size (D50) of as-prepared silver powder determined by laser photo-scattering method was 7.7 μm. D50 was influenced by the condition of atomization angle and drain rate. D50 decreased with decreasing to atomization angle and drain rate. Electron probe micro analysis revealed that the oxygen content in as-prepared silver powder was 50 ppm. The specific resistivity of silver paste decreased to 1.75 × 10−8 Ω·m with increasing the sintering temperature. When silver paste was sintered at 900°C for 10 min, the microstructure of silver paste was densified with the large grain growth.

Physicochemical properties of soya bean protein gel prepared by microbial transglutaminase in the presence of okara

SummaryThe influences of okara on the gelling and secondary protein structure of soya protein isolate (SPI) were investigated. Okara was ultra‐refined by high‐pressure homogenisation. The resulting particle sizes and microscopic morphologies were determined using a laser particle size analyser and a confocal laser scanning microscope, respectively. After okara homogenisation, surface area average particle size (D32) decreased from 49.68 to 23.29 μm and volume average particle size (D43) decreased from 118.94 to 55.08 μm. Dynamic rheological measurements showed that the storage (G′) and loss (G′′) moduli of SPI gelled in the presence of okara were mostly higher than those of SPI gels alone and were increased as the okara amounts increased. Linear law analysis revealed that SPI–okara gels were weak gels and frequency independent. Fourier transform infrared spectroscopy showed that okara and transglutaminase influenced the prevalence of α‐helices, β‐turns, β‐sheet and random coils.

Effect of Compatibilizers on Mechanical and Thermal Properties of High Density Polyethylene Filled with Bio-Filler from Eggshell

In this research work, the effect of compatibilizers on mechanical and thermal properties of ESP/HDPE composites was investigated. High density polyethylene grafted with maleic anhydride (HDPE-g-MA) and ethylene propylene rubber grafted with maleic anhydride (EPR-g-MA) were used to compatibilize the ESP/HDPE composites. The ESP/HDPE composite with and without the compatibilizes was prepared at 20 wt.% ESP. The volume average particle size of ESP was 20.35 µm. The compatibilized HDPE composites were prepared at 2, 5, 8 and 10 wt.% of HDPE-g-MA and at 2, 5, 8 and 10 wt.% of EPR-g-MA, as well. It was found that ultimate stress, yield strength, and elongation at break of the ESP/HDPE composites prepared with HDPE-g-MA increased with increasing HDPE-g-MA content. In addition, Young’s modulus was maximum at 8 wt.% HDPE-g-MA. The composites filled with HDPE-g-MA had improved impact strength with increasing HDPE-g-MA content. On the other hand, the composites with EPR-g-MA showed a decrease in tensile properties and impact strength when increasing EPR-g-MA content. The impact strength of the HDPE composites compatibilized with EPR-g-MA decreased with increasing EPR-g-MA content. In addition, degree of crystallinity of the composites with EPR-g-MA was higher than that of the composite with HDPE-g-MA. Furthermore, compatibilizing ESP/HDPE composites with either HDPE-g-MA or EPR-g-MA did not influence HDPE and ESP decomposition temperatures, HDPE melting temperature and HDPE crystallization temperature.

Synthesis and properties of poly (butyl acrylate-co-methyl methacrylate) copolymer microspheres of tunable size using suspension polymerization

Poly (butyl acrylate-co-methyl methacrylate) copolymer microspheres were prepared by suspension polymerization method whose reactive systems were initiated with azobisisobutyronitrile, cross-linking agent of ethylene glycol dimethacrylate, and suspending agent of poly (vinyl alcohol). The factors of stirring speed and cross-linking agent on the copolymer microsphere conversion rate and particle morphology were investigated. The tunable copolymer microspheres were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermo-gravimetric analysis, and laser particle size analyzer. The results showed that the volume average particle size of copolymer microspheres was 100–130 μm with narrow size distribution, and their degradation temperature was tuned to be much higher than that of the poly (methyl methacrylate), which may provide a candidate material for modifying fluid channels in oil formation.

Structure Analysis of Type-A Zeolites Molecular Sieve Prepared from Stellerite

Type-A zeolites molecular sieve is prepared after crystallization of the type-A zeolites molecular sieve precursor, which is prepared from Stellerite, at temperature of 90 ~ 100°C for 6 hours. It has a complete structure, with crystallinity of 98%, volume average particle size of 3.72µm and particle size distribution which is less than 10µm over 90%. Multi-member rings structure in the type-A zeolites molecular sieve cover each other, forming the cage (β-cage, α-cage, octahedral cage) structure. Nuclei and nanometer particles are formed after the further congregation reaction, and then gather and grow, result in the formation of nanometer crystal particles and transformation to micrometer particles.

Morphology development in polypropylene/polystyrene blends during coalescence under shear

AbstractMorphology development during the coalescence under shear in polypropylene/polystyrene blends was studied in this article. The coalescence was performed by decreasing the shear rate after a fine morphology is obtained at higher shear rate. Time resolved SEM performance indicates that, because of the smaller capillary number, particles of the minor phase are almost spherical during the whole coalescence process. An original sizing method based on SEM is used to describe the time evolution of particle size and their distribution. Initially, the volume–average particle size increases rapidly and levels off before a steady state is obtained, while the number–average particle size increases slowly but monotonously during the whole coalescence process. This two‐step increase in volume average particle size is discussed in terms of coalescence efficiency. Further, an examination of scaling behavior shows that a master curve for particle growth with different compositions is observed by plotting the relative increase in particles size versus the shear strain, confirming that the evolution of particle size could be described by a scaling law. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 666–671, 2007

Preparation of alumina stabilized aqueous Pd colloid by reduction using gamma-radiolysis, UV-photolysis and H2

The techniques of gamma-radiolysis, UV photolysis and hydrogen-induced reduction of aqueous palladium perchlorate to ultrafine particles of Pd, in the presence of alumina sol, have been studied. As compared to H2-induced reduction, both UV photolytic and gamma-radiolytic reduction methods lead to a very stable, brown colored Pd colloid with relatively less absorption in the higher wavelength region and possessing much smaller volume average particle size (62 and 61 nm, respectively). Higher concentration of alumina sol and increase in pH from 1.8 to 7.2, favour the formation of smaller sized particles as determined by the dynamic light scattering technique.

Simultaneous nucleation, condensation, and coagulation in aerosol reactors

A simple model for simultaneous aerosol nucleation, condensation, and coagulation is presented over the entire particle size spectrum approximately the size distribution by a unimodal lognormal function. This model is applied to the constant rate aerosol reactor and four ordinary differential equations suffice to describe the aerosol dynamics in this system. Five dimensionless groups uniquely determine the key product aerosol characteristics (concentration, polydispersity, and volume average particle size) from this reactor. The validity and accuracy of this model are examined by comparing its predictions to known exact solutions at certain limiting cases of aerosol dynamics. The effects of nucleation, condensation, and coagulation on product aerosol characteristics are investigated in the parameter space of the reactor. This model has high potential to be used for the description of aerosol dynamics in highly complex (nonuniform and nonisothermal) aerosol systems for which detailed knowledge of the particle size distribution may not be required.

Latex particle size analysis: I. Flow ultramicroscopy

Accurate determination of particle size and size distribution of synthetic polymer latexes is vital to most latex research and development. Presently, the most commonly accepted absolute method of determining latex particle size is by electron microscopy. This method also offers direct observation of particle shape and clustering. However, there are several disadvantages and limitations. First and foremost is the fact that only dried latexes or replicas of them are examined. Other problems are the representative sampling, problems associated with instrument calibration and spherical aberration of the lenses, and dimensional changes of the particle in the electron beam (1, 2). Finally, the electron microscope is not especially suited for practical routine measurements. Classically ultramicroscopes have been used extensively in colloid studies to determine particle size. This was especially true before the advent of the electron microscope. With the use of the ultramicroscope, the number concentration and volume average particle size can be determined by counting the number of particles in a stationary volume. However, there are many inconvenienees and systematic errors, from Brownian motion and other sources, that have kept the ultramicroscope from wide-