Jet Mill Research Articles

PARTICLE SIZE REDUCTION OF ACECLOFENAC BY USING SURFACTANTS AND MICRONIZATION FOR NANOCARRIER ENTRAPMENT

The Aceclofenac (2-[(2, 6- dichlorophenyl) amine] phenylacetoxyacetic acid) is a Non-Steroidal Anti-Inflammatory category of drug, which is water insoluble drug of BCS class-II which has low solubility and high permeability phenomenon. The particle size reduction technique is used to solubilize the aceclofenac. The particle size of aceclofenac in bulk form is 140-200 microns. In this experiment, The 35 microns particle size was reduced in powder form from 140-200 microns by using Air jet mill and 17.08 microns size was reduced by using dynomill and 33.62 microns particle size was reduced by using Tween 80 as surfactant as considered as lowest particle size. The Labrasol and Na. CMC were also used in this experiment. The equipments used to reduce particle size of aceclofenac are ultra-Turrax (Ultra-sonication), Air jet mill and Dynomill. These all instruments used to reduce the particle size of aceclofenac are safe and not any chemical compound was added in any of the method described above. This study was used to see the uniform nature of the nano- and micro-particles entrapping the aceclofenac drug obtained by High shear homogenization, high pressure homogenization, Solvent-Diffusion evaporation and membrane contactor methods. If the particle size of aceclofenac cannot be reduced less than 14 microns then at the time of Permeation studies the same particle size will enter in Stratum corneum of Skin and entrapped in the carrier matrix. And formation of microns sized particles will obtained while preparing Solid lipid nanoparticles. Keywords: Solubilization, Particle size reduction, Air jet mill, high shear homogenizer, particle size analyzer, Dynomill

HEC-cysteamine particles: influence of particle size, zeta potential, morphology and sulfhydryl groups on permeation enhancing properties

Within this study, the influence of particle size and zeta potential of hydroxyethyl cellulose–cysteamine particles on permeation enhancing properties was investigated. Particles were prepared by four different methods namely ionic gelation, spray drying, air jet milling and grinding. Particles prepared by grinding were additionally air jet milled. All particles were characterized in terms of particle size and zeta potential. The transport of fluorescein isothiocyanate-dextran 4 (FD4) across Caco-2 cell monolayers in the presence of these particles and the decrease in transepithelial electrical resistance (TEER) was evaluated. The cytotoxic effect of the particles was investigated using resazurin assay. Nanoparticles displaying a zeta potential of 3.3 ± 1.3 mV showed the highest enhancement of FD4 transport among all particles with a 5.83-fold improvement compared to buffer only. Due to the larger particle size, particles generated by grinding exhibited a lower capability in opening of tight junctions compared to smaller particles generated by air jet milling. In addition, the results of the transport studies were supported by the decrease in the TEER. All particle formulations tested were comparatively non-cytotoxic. Accordingly, the zeta potential and particle size showed a significant impact on the opening of tight junctions and hence could play an important role in the design of hydroxyethyl cellulose (HEC)-cysteamine-based nano- and micro-particles as drug delivery systems.

A Novel Process for Making Spherical Powders of High Nb Containing TiAl Alloys

A novel process was developed to make micro-fine spherical high Nb containing TiAl alloyed powders in quantity. Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y(at%) ingot prepared by vacuum induction melting was heat-treated for homogenization, and then machined with a crusher. The chippings were refined by fluidized bed jet milling, and subsequently spheroidized with radio frequency (RF) argon plasma. The effects of processing parameters on powder characteristics were studied. By fluidized bed jet milling, the particle size and distribution uniformity both decline with the rise of classifier frequency. Above 5800rpm, the number-average diameter is lower than 20μm with a bimodal particle size distribution. The powders consist of coarse plate-shaped particles and some finer flaky debris, and with the further rise of the frequency, the amount of debris gradually increases. The plasma-spheroidized powders are found to possess good sphericity and composition homogeneity with phase dominated by supersaturated α2-Ti3Al. The granulometric characteristics of the spherical powders strongly depend on those of the feed powders. For the jet milled powders below 5800rpm, due to the relatively lower size distribution uniformity, the fine particle fraction reduces after spheroidization, which causes an obvious improvement of distribution uniformity and the corresponding increase of number-average diameter

Effect of microparticulated wheat bran on the physical properties of bread

Wheat bran and flour mixtures were used in a bread formulation to improve its quality characteristics. Wheat bran was microparticulated using a jet mill, and this microparticulated wheat bran (MWB) was substituted for a portion of wheat flour. As the MWB content increased, water-holding capacity, hardness and springiness increased while the swelling property decreased slightly. The hardness of bread containing MWB was lower than that made with commercial whole wheat flour (WWF). Bread containing 7% MWB had a higher specific volume (8.3%) than that of WWF bread. Enthalpy of dough decreased with increasing MWB content, and peak viscosity and breakdown decreased with increasing setback. Inner crust structures of bread containing MWB showed a slight reduction in gelatinization and gluten development in comparison with wheat bread. These results indicate that MWB could be used as a diet-enriching bread ingredient while maintaining bread quality.

Analyzing the quality of grinding and mixing of copper and chromium powders in a new-type mill

The potential use of a new-type mill developed at the Frantsevich Institute for Problems of Materials Science to produce copper and chromium powder mixtures intended for the manufacture of electrical-grade materials is studied. The mill ensures mechanical grinding of loose materials by mechanisms similar to those acting in vortex and jet mills. The greater powder refinement in this mill is due to the sliding interaction of particles with abrasive surfaces of the mill chamber. It is shown that common grinding of electrolytic copper and reduced or aluminothermic chromium for 10–30 min in argon promotes variation in the shape of particles, facilitates their mixing, and provides uniform distribution of components in the mixture.

ChemInform Abstract: Rare Earth Elements and Permanent Magnets (Invited)

AbstractReview: 10 refs.

Application of a simplifying model to the breakage of different materials in an air jet mill

This paper describes the application of a unifying ‘master curve’ model for single impact size reduction in an air jet mill. Based on a dimensional analysis and a modified fracture mechanical theory, it enables to relate the weight percentage of broken particles under sieve cut size to the mean sieve cut size of the studied material, the net kinetic energy provided to the material, the number of impacts and a global parameter fMat.. Altogether 11 sieve cuts of different materials are impacted in an experimental air jet mill. Minimum breakage energies are derived and are shown to vary with a power function of the sieve cut size. The simplifying model is then successfully applied and enables to derive the fMat. parameters. In our situation, the experimental data do not show a direct relationship between fMat. and the minimum breakage energy and sieve cut size for all the materials.

Mathematical Modeling and Implementation of Residual Stress Mapping From Microscale to Macroscale Finite Element Models

The paper reviews a development of mathematical algorithms and implementation of mapping residual stress profiles from microscale to macroscale finite element (FE) models. A shot-peening simulation of Inconel 718 is conducted using the finite element method (FEM) to obtain the residual stress profiles which are used as an input in the developed mapping algorithms. Residual stress profiles induced by the shot-peening processes are mapped into different FE models including a perforated plate, a model with a complex surface, and an aero-engine vane component. The mathematical mapping algorithms and formulations are developed for 2D and 3D FE models where residual stress profiles obtained experimentally, numerically, or analytically for different manufacturing processes including shot-peening, water jet machining, milling, turning, roller burnishing, laser machining and peening, electro discharge machining, etc., can be mapped on FE models with complex geometries. The implementation and the results for the mapping techniques are presented and discussed in detail.

Ultrafine wool powders and their bulk properties

Wool powder may be utilized in advanced applications, notably composite materials, biomedical and cosmetics depending on the development of a suitable powder fabrication process and understanding of powder properties. This paper discusses a novel approach to mill viscoelastic wool fibres using a combined wet attritor and air jet milling (AJM) process. Results show that 5h attritor milling followed by spray drying can produce wool powder with a BET surface area of 14.89m2/g and volume based d(0.5) of 4μm. Despite absence of any milling pre-treatments, the particles are much smaller than previously prepared wool particles using other methods. Subsequent AJM further reduces d(.5) to 1.5μm, but creates loose aggregates which results in their low bulk density. The aggregates can be disintegrated using a strong consolidating force and such AJM powder can be compressed to 45% of the original volume. Rheological measurements suggest strong cohesion and poor flowability of wool powders. Consolidated AJM powder is even more cohesive with a flow function of 1.64 compared to spray dried powder without AJM which has a flow function of 3.74. The results are important for processing and applications of these novel organic fibre powders, where ultrafine particles are needed and understanding of powder packing and flow behaviour is important.

Rare earth elements and permanent magnets (invited)

Rare earth (RE) magnets have become virtually indispensible in a wide variety of industries such as aerospace, automotive, electronics, medical, and military. RE elements are essential ingredients in these high performance magnets based on intermetallic compounds RECo5, RE2TM17 (TM: transition metal), and RE2TM14B. Rare earth magnets are known for their superior magnetic properties—high induction, and coercive force. These properties arise due to the extremely high magnetocrystalline anisotropy made possible by unique 3d-4f interactions between transition metals and rare earths. For more than 40 years, these magnets remain the number one choice in applications that require high magnetic fields in extreme operating conditions—high demagnetization forces and high temperature. EEC produces and specializes in RECo5 and RE2TM17 type sintered magnets. Samarium and gadolinium are key RE ingredients in the powder metallurgical magnet production processes which include melting, crushing, jet milling, pressing, sintering, and heat treating. The magnetic properties and applications of these magnets will be discussed. We will also briefly discuss the past, current, and future of the permanent magnet business. Currently, over 95% of all pure rare earth oxides are sourced from China, which currently controls the market. We will provide insights regarding current and potential new magnet technologies and designer choices, which may mitigate rare earth supply chain issues now and into the future.

Microwave property of micron and sub-micron Fe90Al10 flakes fabricated via ball milling and jet milling routes

Fe90Al10 flakes with micron- and submicron-sizes were fabricated via different milling routes. Traditional wet ball-milling process with pure ethanol as additive was performed to prepare micro-sized Fe/Al flakes. With increasing wet-milling time, the flake size increases. For Fe/Al submicron-flakes, Micron-Master Jet Pulverizer (so called jet mill) was employed. The results reveal that Fe90Al10 submicron-flakes with an average lateral size of 500nm could be obtained through the combination of ball milling and jet milling. Microwave performance of the obtained Fe90Al10 flakes with different sizes was further studied. The complex permittivity and permeability were measured by dispersing as-prepared flakes into epoxy resin with a powder-to-epoxy volume ratio of 1:10. The results showed that flaky particles possess obvious advantage over the quasi-spherical ones on the microwave property. The theoretical calculation on reflection loss (RL) was also investigated in the range of 0.1–18GHz. The results show that the composite including 50μm flaky particles shows the strongest reflection loss peak. The optimal thickness was 3.1mm and the RL value reached −34dB at the frequency of 7.6GHz. Compared with as-prepared micron-flakes, the resonance frequency of the submicron flakes shifted toward higher frequency band, which is probably due to the reduction of skin effect because of the smaller size. In our study of thickness effect, the resonance peak shifted to higher frequency range with decrease in thickness for the composite containing 500nm flakes. And the optimal thickness of the submicron flakes was 1.9mm with the resonance peak at 14.2GHz with a reflection loss value exceeding −10dB in the frequency range between 12.2 and 16.8GHz. The results reveal that the submicron flakes have the potential for making lightweight broad-band microwave absorbers applied in high frequency range.

Influence of Solvent on the Morphology and Subsequent Comminution of Ibuprofen Crystals by Air Jet Milling

Crystal morphology plays an important role in drug processing and delivery, which may be controlled during crystallisation. In this study, ibuprofen particles with different size and morphology were produced by controlled crystallisation in order to evaluate their impact on particle size reduction. Results suggest that the micronisation behaviour of ibuprofen was markedly influenced by the morphology and size of starting materials. It was possible to reduce the size of ibuprofen particles to sizes less than 5 µm during dry milling, which is markedly below the reported brittle-ductile transition size. Results also indicate that the particle size reduction mechanism is influenced by the size and morphology of the starting ibuprofen crystals. Dissolution behaviour of ibuprofen was shown to be influenced by the solid surface chemistry of micronised drug particles. The molecular modelling study provided deeper understanding of the experimental findings observed in this study.

Kerf Profile Modelling in Abrasive Waterjet Milling

The Abrasive Water Jet milling process is demonstrated to be an efficient technology for milling low machinability materials. Although its capability is demonstrated, the industrial application of this technology requires a depth control, for which a work focused in process modelling is needed. This research work introduces a model to predict the kerf shape in AWJ slot milling in Aluminium 7075-T651 in terms of four important process parameters: pressure, abrasive mass flow rate, stand-off distance and traverse feed rate. A hybrid evolutionary approach was employed for modelling the profile through two parameters: the maximum cutting depth and the full width at half maximum. Both the maximum depth and the width were also modelled as a function of aforementioned process parameters based on Analysis of Variance and regression techniques. Combination of two models resulted in an adequate strategy to predict the kerf shape for different machining conditions.

Fabrication of micro-fine high Nb-containing TiAl alloyed powders by fluidized bed jet milling

A fluidized bed jet milling process was used to make micro-fine high Nb-containing TiAl alloyed powders from the chippings obtained by crushing the Ti-45Al-8.5Nb-(W,B,Y) ingot. The influences of classifier frequency on powder characteristics were investigated. The results show that the powders with controlled average particle size can be prepared on a large scale. The powders with different sizes are all dominated by γ with a minor amount of α2-Ti3Al. The particle size significantly decreases with the classifier frequency increasing. At a classifier frequency higher than 38 Hz, the average particle size of the ground powders is lower than 25 μm. The powders are composed of two different sizes of particles: shaped particles and some clastic particles, and both particle sizes meet the log-normal distribution. With the classifier frequency increasing, the both sizes decrease; meanwhile, the proportion of the clastic particles gradually increases, and the size distribution span value of the ground powders increases correspondingly.

Production of grey cast iron powder via target jet milling

Target jet milling was used for the first time to convert cast iron scraps to powder. An experimental apparatus was designed which comprised a compressor, a mixing section, a nozzle, an impact chamber and two suction machines. Milling parameters i.e. the target to nozzle distance, the feed rate and the impact angle were optimized through appropriate tests. The travel distance of 8cm and the impact angle of 90° were found to be ideal parameters of milling. The effect of feed rate on production of powders greater than 45μm was found to be opposite to the production of the fines (<45μm). Investigation of the fragmentation procedure of particles revealed that, the existence of graphite flakes in cast iron matrix plays the most important role in particle breakage.

Development of a novel ultra cryo-milling technique for a poorly water-soluble drug using dry ice beads and liquid nitrogen

A novel ultra cryo-milling micronization technique has been established using dry ice beads and liquid nitrogen (LN2). Drug particles were co-suspended with dry ice beads in LN2 and ground by stirring. Dry ice beads were prepared by storing dry ice pellets in LN2. A poorly water-soluble drug, phenytoin, was micronized more efficiently using either dry ice beads or zirconia beads compared to jet milling. Dry ice beads retained their granular shape without pulverizing and sublimating in LN2 as the milling operation progressed. Longer milling times produced smaller-sized phenytoin particles. The agitation speed for milling was optimized. Analysis of the glass transition temperature revealed that phenytoin particles co-ground with polyvinylpyrrolidone (PVP) by dry ice milling were crystalline, whereas a planetary ball-milled mixtures process with zirconia beads contained the amorphous form. The dissolution rate of phenytoin milled with PVP using dry ice beads or zirconia beads was significantly improved compared to jet-milled phenytoin or the physical mixture. Dry ice beads together with LN2 were spontaneously sublimated at ambient condition after milling. Thus, the yield was significantly improved by dry ice beads compared to zirconia beads since the loss arisen from adhering to the surface of dry ice beads could be completely avoided, resulting in about 85–90% of recovery. In addition, compounds milled using dry ice beads are free from abraded contaminating material originating from the beads and internal vessel wall.

Novel Ultra-Cryo Milling and Co-grinding Technique in Liquid Nitrogen to Produce Dissolution-Enhanced Nanoparticles for Poorly Water-Soluble Drugs

A novel ultra-cryo milling micronization technique for pharmaceutical powders using liquid nitrogen (LN2 milling) was used to grind phenytoin, a poorly water-soluble drug, to improve its dissolution rate. LN2 milling produced particles that were much finer and more uniform in size and shape than particles produced by jet milling. However, the dissolution rate of LN2-milled phenytoin was the same as that of unground phenytoin due to agglomeration of the submicron particles. To overcome this, phenytoin was co-ground with polyvinylpyrrolidone (PVP). The dissolution rate of co-ground phenytoin was much higher than that of original phenytoin, single-ground phenytoin, a physical mixture of phenytoin and PVP, or jet-milled phenytoin. X-Ray diffraction showed that the crystalline state of mixtures co-ground by LN2 milling remained unchanged. The equivalent improvement in dissolution, whether phenytoin was co-ground or separately ground and then mixed with PVP, suggested that even when co-ground, the grinding of PVP and phenytoin occurs essentially independently. Mixing original PVP with ground phenytoin provided a slight improvement in dissolution, indicating that the particle size of PVP is important for improving dissolution. When mixed with ground phenytoin, PVP ground by LN2 milling aided the wettability and dispersion of phenytoin, enhancing utilization of the large surface area of ground phenytoin. Co-grinding phenytoin with other excipients such as Eudragit L100, hypromellose, hypromellose acetate-succinate, microcrystalline cellulose, hydroxypropylcellulose and carboxymethyl cellulose also improved the dissolution profile, indicating an ultra-cryo milling and co-grinding technique in liquid nitrogen has a broad applicability of the dissolution enhancement of phenytoin.

Immobilization of Lysozyme on Biomass Charcoal Powder Derived from Plant Biomass Wastes

Biomass charcoal powder (BCP) was used as a carrier matrix for immobilization of chicken egg white lysozyme. BCP was derived from plant biomass wastes such as dumped adzuki beans by pyrolysis without combustion under nitrogen atmosphere and grinding with a jet mill. The amount of lysozyme immobilized on BCP of adzuki beans by adsorption was 11 μmol/g (0.16 g/g) at pH 7.0. The optimum pH values for free and immobilized lysozyme activities were 6.8 and 7.2, respectively. The optimum temperature for both free and immobilized lysozyme activities was 25℃. The half-life of immobilized lysozyme exhibited 1.8-fold compared to that of free lysozyme at 5℃. Moreover, the half life of immobilized lysozyme was 7 times greater than that of lysozyme at 90℃.

Influence of the Operating Temperature on the Ultrafine Grinding in Superheated Steam Jet Mill

Effects of operating temperature on the fineness and yields of the ultrafine circulating fluid bed fly ashes (CFBAes) have been studied. Results show that the temperature of selection zone increased faster than that of crushing zone. Introduction of secondary air decreased the temperature of crushing zone, which would make the classifier invalid. Also, ambient temperature and insulation measures have a great impact on the ultrafine grinding in superheated steam jet mill

結晶粒微細化によるNd-Fe-B焼結磁石の高保磁力化

For the purpose of increasing the coercivity of the Nd-Fe-B sintered magnets without Dy substitution, we explored a possibility of enhancing the coercivity by grain size reduction of the sintered body by employing the starting powder with an ultimately small particle size. To produce Nd-Fe-B alloy powder with such a small particle size, and to handle it to produce sintered bodies without oxidation, we developed a special jet mill and a special process called pressless process (PLP). By utilizing these techniques, it has become feasible to produce Nd-Fe-B sintered magnets with a coercivity of 1.59 MA/m without Dy substitution which is compared with 0.87 MA/m for the commercially available Nd-Fe-B sintered magnets containing no Dy.