Powder Flow Properties Research Articles

The Use of the Gas Nitriding Process for the Nitridation of Powder for Laser Powder Bed Fusion

AbstractAdditive manufacturing in the powder bed by means of laser powder bed fusion (L-PBF) combines the fast production of metallic components with complex geometrical structures with a high degree of customization and low raw material consumption. However, there is a high demand for the development of new alloys to achieve the desired properties of additively manufactured parts. Due to a lack of knowledge, only a small group of steel powders are currently available for L-PBF. As an example, Cr and CrMn steel powders with additional alloyed nitrogen could be used for L-PBF products for Ni-free medical devices. The present work investigates the possibility of alloying nitrogen to austenitic steel alloy powder and high alloyed martensitic steel powder via gas nitriding. For this purpose, an X30CrMo7-2 powder and an AISI 316L powder for additive manufacturing were arranged to form powder beds of different heights and nitrided at different temperatures, times and nitriding potentials. The nitrogen content was determined from the samples taken at different heights of the powder beds. Individual powder particles were examined by means of metallography, scanning electron microscopy and electron probe micro analysis. It is shown that the nitrogen concentration in the powder is essentially determined by the nitriding temperature. In the X30CrMo7-2 powder, nitride precipitation also occurs at high temperature and N and C gradients are present in the particles with an average nitrogen content of up to 4 mass%. In the 316L powder, a homogeneously distributed nitrogen content of 0.35 mass% can be achieved after gas nitriding at 420 °C for 24 h. The flow properties of both powders are hardly affected by gas nitriding.

Exploring the impact of extrinsic lactose fines, a USP modified sampling device and modified centrifuge tube on the delivered dose uniformity and drug detachment performance of a fluticasone propionate dry powder inhaler

The present study aimed to probe influences exerted by extrinsic lactose fines on drug detachment and delivered dose uniformity (DDU) of fluticasone propionate (FP) dry powder inhaler (DPI). Extrinsic lactose fines (0–35%) containing lactose pre-blends were formulated using a low shear 3D shaker mixer and systematically analyzed for various physicochemical properties. Moreover, formulated FP DPIs were assessed for drug detachment by force distribution concept and the DDU using two different sampling devices i.e. the Dosage Unit Sampling Apparatus (DUSA) and USP modified glass sampling device (modified DUSA) coupled with Aerolizer® device at 60 L/min. The physicochemical assessment of control and pre-blend lactose samples displayed significant differences in particle size, surface roughness, degree of surface irregularity and powder flow properties. The formulated FP DPIs displayed monolayer-type FP distribution across the lactose particles in laser Raman spectroscopy with acceptable content uniformity (~100%). Drug detachment study using a modified centrifuge tube showed significant differences in drug detachment profile. The FP DPI formulated using 20% of lactose fines showed the lowest drug detachment force (349.45 gf) as compared to the other lactose samples. Moreover, the FP DPI formulated using 20% of lactose fines demonstrated acceptable mean delivered dose (107.76 and 110.62 μg) with the lowest coefficient of variation using DUSA and modified DUSA, respectively. The present study is the first comprehensive summary of delivered dose uniformity using two different USP sampling devices. Accordingly, these observations may be of high significance for both intuitional and industrial formulators.

Preparation and Characterisation of Sustained Released Dosage Form for Ketoprofen using Natural Gums

Objective: The major objective of this work is to formulate a sustained launch matrix drugs the use of cashew and neem gum. Ketoprofen turned into decided on as a version drug because of the low half-life. Hencesustained dosage forms are formulated to lessen the dosage frequency. Methods: Ketoprofen matrix tablets were formulated by employing cashew gum and neem gum as a release rate retardant material and used in10%, 20%, 30% and 40% Concentration levels. Wet granulation method was used to develop sustained release tablets. Tablet was evaluated in terms of flow properties of blended powders and the average weight, drugcontent hardness, in vitro dissolution studies and fourier transformationinfrared spectroscopyn (FT-IR) were determined. Drug release was evaluated with zero and the first order for release kinetics, Higuchi, Korsmeyerpeppas models for the release mechanism. Results: The hardness of the tablets ranged from 5.5 to 6.8 Kg/cm2 and the friability values were less than 1% indicating that the matrix tablets were compact and hard. All theformulations satisfied the content of the drug as they contained 99.1 to 100.8 % of ketoprofen, KCS8 released 99.2 of drug in 12 hrs and considered as optimized formulas. KCS8 formulation has shown drug release byzero order kinetics. This data reveals that drug release follows fickian diffusion mechanism Peppas model. Conclusion: The present study could establish the suitability of neem gum, cashew gum as Controlled released(CR) polymer in the design of matrix tablets.

Designing high-performance colour cosmetics through optimization of powder flow characteristics.

Explore the impact of powder flow properties such as flow energy and compressibility on the performance characteristics of foundation powders such as cake strength and pay-off. FT4 Powder Rheometer from Freeman Technology was utilized to explore various powder compositions. The three major tests performed were flowability test, compressibility test and shear cell test. The results highlight that the sample which has higher compressibility has the better cake strength, and the sample which requires lower total energy has better pay-off. Particles or samples with lower total flow energy, should have easier flow, therefore, should have better pay-off. Samples and components with higher compressibility, should hold the structure better, therefore, should have better cake strength. Talc has the highest compressibility and lowest flow energy. Foundation sample 5 has the highest concentration of talc and also has the best performance. The lower the total flow energy, the easier it is for the powder to flow, and have better pay-off. Powder compressibility correlates with cake strength which means that a sample with better compressibility consequently has the better cake strength. Samples 5 and 10 require less total flow energy, have lower shear stress, and higher compressibility, therefore, have better final performance. Both samples 5 and 10 have higher talc concentrations compared to other formulations.

The use of novel tools for the assessment of powders and granules flow properties and for the analysis of minitablets compression process

Objective: The purpose of this study was to apply the rheological measurements to assess the flow properties of powders and granules and to compare the results with the standard pharmacopeial tests. Quality by design approach was utilized to better understand the compression of the solids into minitablets.Significance: Insights are provided regarding the methodology of rheological properties of powders and granules using powder flow analyzer (PFA). The ‘six sigma’ approach was presented as a tool for assessment of the minitablets manufacturing process.Methods: Pharmacopeial methods and rheological tests using PFA were performed to assess the flow properties of designed powder and fractionated granule mixtures – placebo and with benzodiazepines. Compression of 2.5 and 3 mm minitablets was carried out and the compression force registered during the process and weight uniformity were statistically analyzed by calculating the capability indices.Results: The flow rate measurement and cohesion test (PFA test) resulted in the best differentiation between mixtures. Higher values of capability indices were obtained for processes in which granule mixtures with better flow properties were compressed and 3 mm minitablets were produced and the usefulness of QbD tools in assessment of minitablets compression process was confirmed.Conclusion: Performed study showed that the flow properties are the critical quality attributes determining the performance of minitablets compression. The cohesion test is the most discriminative to distinguish the analyzed mixtures. Capability indices can be used to assess the manufacturing process as a useful tool in pharmaceutical development of minitablets.

Flow Function of Pharmaceutical Powders at Low-Stress Conditions Can Be Inferred Using a Simple Flow-Through-Orifice Device

Multiple pharmaceutical powder processes operate at stresses lower than utilized in typical lab-scale shear cell testing. To bridge this gap, we developed a method to determine intrinsic powder flow properties, in particular, flow function (FFc), under such low stresses. A simple, commercially-available flow-through-orifice device (Flodex™ apparatus) was selected. By developing a theoretical framework using Jenike’s radial stress field analysis, the major principal stress and FFc of the tested powder can be derived from the otherwise empirical “Flodex” experiment. This method was applied to 10 distinct pharmaceutical powders. The major principal stresses associated with the test were estimated to be in the order of 100 Pa, significantly lower than what is achievable using shear cell-based methods. The resulting FFc values are generally consistent with the data extrapolated from ring shear testing. We showed that for pharmaceutical powders, FFc decreases with decreasing consolidation stress, but the values are always greater than 1. Therefore, the threshold for poor/acceptable flowability (by FFc) should be used with caution at low-stress conditions. Through this work, we showed that by integrating the radial stress field theory with a simple flow-through-orifice experiment, intrinsic powder flow properties under low stresses could be reliably determined.

Lactose monohydrate flow characterization using shear cell method

The flow properties of pharmaceutical powders have a great importance in the manufacturing of solid dosage forms. In order to ensure the performance in the production line this parameter must be determined. There are several methods described in European Pharmacopeia that are used to measure these properties. Some of them were used in this study and the results obtained from conventional methods (Conv) and shear cell using the powder flow tester (PFT) showed differences that were more evident in fractions with smaller particle size (F < 63) and for bulk powder (FTotal). The various powder behaviors showed to be related with the size of the particles. An increase of the ffc (Flow Index) was observed with the increase of the particle size. It was also found for the different fractions that the ffc always increases with increasing major principal consolidation stress (σ1). This study shown to be predictive because it also allowed the behavior profiles of other LactMN fractions to be known by interpolation of the median size (Dv50) or σ1 values ranged between the studied intervals. Furthermore, it was also observed that ffc of the FTotal was similar to the F < 63, showing the same behavior under σ1. The occurrence of caking was not observed.

Phenytoin-loaded lipid-core nanocapsules improve the technological properties and in vivo performance of fluidised bed granules.

Lipid-core nanocapsules (LNCs) were recently reported by our group as a suitable binder system to produce fluidised bed granules. However, there is still a lack of knowledge about the influence of using these nanocarriers loaded with a drug on the properties of the granules and their in vivo performance. Therefore, this study was designed to produce innovative fluidised bed granules containing phenytoin-loaded LNCs (LNCPHT) as a strategy to evaluate the influence of the presence of the drug-loaded nanocarriers on their in vitro and in vivo properties. Granules were produced using a mixture of maltodextrin and phenytoin (1:0.004 w/w) as substrate. They were prepared by fluid bed granulation using water or LNCPHT as the liquid binder, affording good yields (73-82%) of granules with low moisture content (<5%). Granules prepared with LNCPHT had larger mean size (122μm) compared to maltodextrin primary particles (50μm) due to the formation of solid bridges. Moreover, the use of LNCPHT as the liquid binder improved their powder flow properties. The nanocarriers were recovered after aqueous dispersion (3.00mg.mL-1 of PHT) with a redispersibility close to 90%. After reconstitution in water, granules containing LNCPHT showed an improved dissolution behaviour compared to those prepared without them. In addition, they showed a higher mucoadhesive effect due to a combined effect of the LNCPHT and maltodextrin in the interactions with porcine intestinal mucosa. Regarding the in vivo studies, granules containing the combination of non-encapsulated PHT and PHT-loaded lipid-core nanocapsules increased the latency to seizures compared to placebo granules, showing effective anticonvulsant effect in mice. In conclusion, the use of drug-loaded nanocapsules as binder is an encouraging approach to produce fluidised bed mucoadhesive granules with improved technological properties and in vivo performance.

Physical and flow properties of pseudocereal-based protein-rich ingredient powders

Knowledge of bulk handling properties of food powders is essential in the design of industrial equipment and selection of appropriate powder handling operations. The objectives of this study were to determine the physical and flow properties of plant-based regular and protein-rich flours to establish relationships between powder physical and bulk handling properties as influenced by protein enrichment. A number of physical properties (bulk density, flowability, wall friction and compressibility) were assessed for 11 regular- and protein-rich flours from pseudocereals (amaranth, buckwheat, quinoa) and cereals (rice and maize). Relevant physicochemical properties such as particle size distribution, microstructure and water sorption behaviour were also studied. The protein-rich pseudocereal flours had irregular-shaped, rough surfaces with mean particle diameters ranging from 96.5 to 215 μm. The compressibility indices (42.6–51.4%) were higher for the former compared to the regular protein content powders and they displayed lesser tendency to uptake water with increasing relative humidity. Analysis of the flow behaviour showed the protein-rich flours to be more cohesive with higher wall friction angle values than the regular protein content powders. The new information obtained in this study is critical in optimising the processing, stability and applications of these value-added high-protein pseudocereal ingredient powders.

Potential of DEM for investigation of non-consolidated flow of cohesive and elongated biomass particles

The evaluation of the flow properties of biomass powders is essential for the design of handling systems within a thermochemical valorization context. The Discrete Element Method (DEM) is a valuable tool for simulating the bulk behavior of granular materials that has rarely been used for biomass feedstocks. This work focuses on the numerical investigation of the flow of raw and torrefied biomass particles in a loose and dynamic conditioning using a rotating drum. The relevance of DEM parameters calibrated using bulk experiments (angle-of-repose, bulk density, retainment ratio) is tested by comparison with experimental data obtained using a rotating drum system. The calibrated DEM material model considers the elongated, submillimetric and cohesive nature of the biomass powder. Several flowability descriptors (Upper Angle of Stability, size of avalanches, fraction of revolution to trigger events and irregularity of the free surface) are evaluated using both experimental data and DEM simulations. DEM results reproduced well the experimental trends and distinguished between the different cohesive extent of the samples. DEM is therefore a relevant technique for assessing flowability of biomass powders in a non-consolidated dynamic flow. This paves the way for investigating the effects of particle characteristics on bulk flow, which are briefly discussed.

Dense and homogeneous MOX fuel pellets manufactured using the freeze granulation route

AbstractMOX fuels (UO2‐PuO2) are used in light water nuclear reactors of several countries and are also potential candidates for the fast neutron reactors. Industrial MOX is currently manufactured by a dry route process, involving steps with fine powders. To reduce dusting, enhance MOX powder flow properties, and decrease manufacturing scrap rate, a new wet route process is investigated: the freeze granulation of concentrated water‐based powder suspensions having optimized rheology and dispersion properties. Highly flowable, dustless, and easy‐to‐press MOX granules have been elaborated. Sintering green compacts made of such granules gives highly dense and defect‐free pellets that have a very homogeneous U‐Pu spatial distribution, thus improving the fuel characteristics. Indeed, MOX fuels devoid of large Pu‐rich aggregates are thought to have a better behavior under irradiation in reactors by limiting/preventing the formation of the typical high burnup structure.

Flow behavior of cocoa pulp powder containing maltodextrin

Abstract This study aimed to evaluate the influence of maltodextrin addition on the flow properties of cocoa pulp powder obtained by spray and freeze drying. Cocoa pulp samples received 15% and 30% (m m-1) maltodextrin DE20. Two drying methods were used, spray and freeze drying. Powder morphology was evaluated through scanning electron microscopy (SEM). Wall friction angle, bulk density and tapped density were determined. Carr index (CI), Hausner ratio (HR) and flow index (FI) were used to evaluate powder flow. The particles powders obtained by spray drying showed rounded shapes, whereas the freeze dried powder showed irregular shapes. Increased maltodextrin concentration in the samples altered the powder particle size by spray drying and powder particle surface by freeze drying. The powder by spray drying of the sample with 30% of maltodextrin showed smallest wall friction angles, 13.4 to 14.9. The powder by freeze drying of the samples with 15% and 30% of maltodextrin showed wall friction angles between 14.0 and 20.6. Regarding flow, the powders by spray drying containing 30% of maltodextrin showed the best CI, HR and FI, 24.88, 1.33 and 4.88, respectively, being considered an acceptable flow. According to CI, HR and FI values, samples with 15% of maltodextrin produced powder classified as difficult flow in both methods applied. The higher maltodextrin concentration in cocoa pulp, the lower agglomeration in the powder by spray drying and the smoother particles surfaces in the powder by freeze drying. The addition of maltodextrin to the samples, for both drying methods, improve the powder flow and decrease the powder cohesion.

Maltodextrin on the flow properties of green coconut (Cocos nucifera L.) pulp powder

ABSTRACT The study of the flow properties and particle surfaces of a food powder is essential for predicting its behaviour during processing and commercialization. The objective of this work was to determine the powder flow properties of lyophilized green coconut pulp with different concentrations of maltodextrin. Samples containing 0, 5, 10 and 15% (m/m) maltodextrin were lyophilized, and the flow index (FI), wall friction angles and densities were determined. The microstructure of the powders was evaluated by scanning electron microscopy (SEM). The samples containing 0 and 5% maltodextrin showed 1.87 FI, classifying them as very cohesive powders, and those containing 10 and 15% cohesive powder showed 2.12 and 2.43 FI, respectively. The powder densities varied from 138.6 to 287.6 kg/m3, and the wall friction angle varied from 15.8 to 39.8°. The powder particles presented irregular shapes and rough surfaces, especially in powders containing 0, 5 and 10% maltodextrin. The powder containing 15% had smoother and less agglomerated surfaces. An increase in the amount of maltodextrin added to the pulp made the particles smoother and denser and improved the fluidity of the powder.

Karakteritik sifat alir bubuk teh hijau yang diproses dengan metode penepung berbeda

Recently, the public interest in green tea powder is increasing. Green tea powder is produced through the process stage: withering in hot steam, drying, and reducing size. The size reduction process on green tea powder is an important step because it will affect the characteristics of the powder flow properties. This study aims to determine the flow properties of green tea powder processed by different milling method. The milling method used are disc milling (DM) and stone milling (SM). Green tea powder was analyzed including moisture content, particle size distribution using dynamic laser scattering method, determined of bulk density (ρb), and tapped density (ρtap) to find out the Carr Index (CI) and Hausner Ratio (Hr). In addition, the lightness of color and shape and morphology of green tea powder were observed with SEM. The results showed that green tea powder produced from different milling methods have a Carr Index of 15 with “Good” flow properties. DM method produced darker green tea powder with L value (lightness) 49.91 and larger particle size (D50: 38.6 µm) compared with green tea powder produced by the SM method. Determination of flow properties of green tea powder can be applied for the utilization and development of food products and pharmaceutical products based on green tea powder.

Continuous Formulation Approaches of Amorphous Solid Dispersions: Significance of Powder Flow Properties and Feeding Performance.

Preparation and formulation of amorphous solid dispersions (ASDs) are becoming more and more popular in the pharmaceutical field because the dissolution of poorly water-soluble drugs can be effectively improved this way, which can lead to increased bioavailability in many cases. During downstream processing of ASDs, technologists need to keep in mind both traditional challenges and the newest trends. In the last decade, the pharmaceutical industry began to display considerable interest in continuous processing, which can be explained with their potential advantages such as smaller footprint, easier scale-up, and more consistent product, better quality and quality assurance. Continuous downstream processing of drug-loaded ASDs opens new ways for automatic operation. Therefore, the formulation of poorly water-soluble drugs may be more effective and safe. However, developments can be challenging due to the poor flowability and feeding properties of ASDs. Consequently, this review pays special attention to these characteristics since the feeding of the components greatly influences the content uniformity in the final dosage form. The main purpose of this paper is to summarize the most important steps of the possible ASD-based continuous downstream processes in order to give a clear overview of current course lines and future perspectives.

Application of feeding guiders to improve the powder distribution in the two scales of roller compactors.

Roller compaction is a continuous dry granulation process, where the powder is compressed between two counter-rotating rollers and compacted into ribbons. The quality and homogeneity of the granulate is determined by the uniformity and porosity of the ribbon, which depends on the feeding process of the primary powder to the rollers, the flow properties of the primary powder and process parameters such as roller forces. Previous work was conducted to improve the powder flow and distribution in the feeding zone by developing new feeding guiders, which are located in the feeding zone close to the rollers on the lab-scale roller compactor Alexanderwerk WP120 Pharma (Yu et al., 2018). These new feeding guiders were used to reduce the amount of powder that is delivered to the centre of the rollers and increase the amount of powder that is delivered to the sides of the rollers, in comparison to the original feeding guiders. This modified concept using new feeding guiders has been applied to the large-scale roller compactor Alexanderwerk WP200 Pharma in the present work. In order to evaluate the homogeneity of the ribbon properties across the ribbon width, the temperature profile and porosity distribution across the ribbon width were measured. The new feeding guiders resulted in ribbons being produced with a more uniform temperature profile and porosity distribution across the ribbon width when using the small and large scale roller compactors at different process parameters.

Dynamic ball indentation for powder flow characterization

In industrial processing and manufacturing, characterizing the flowability of particulate solids is of particular importance both for reliable powder flow and for a consistent production rate. Shear testing is the most widely used method for powders subjected to moderate or high stresses, and under quasi-static conditions. However, this method is not suitable for measuring the powder flow properties occurring in dynamic systems, such as powder mixers and screw conveyors. In this study, the rheological behaviour of powders at high shear rates has been evaluated by the ball indentation method. The technique, which simply consists of dropping a ball onto a cylindrical bed of previously consolidated powder, directly measures the material hardness, which is related to the unconfined yield stress by the constraint factor. The impact of the ball on the bed is recorded with a high-speed camera to determine velocity and penetration depth. The hardness against the strain rate is considered for four different materials. Because of their difference in particle size, and by using a range of drop heights and a range of indenter densities, the intermediate regime of flow has been fully analyzed. Although hardness is constant in the quasi-static condition, it results to be strain rate dependent in the intermediate regime of flow. Finally, a predictive correlation that allows the operator to choose the best operating conditions for achieving the desired flow regime is proposed, and the unconfined yield strength of the materials is inferred.

Formulation and characterization of β‐carotene loaded solid lipid nanoparticles

Encapsulation has been used widely for improving the stability and bioavailability of various bioactive compounds. Among the nanodelivery systems, solid lipid nanoparticles (SLN) are capable of delivering bioactive compounds with sustained release properties. In this study, β‐carotene loaded SLN (SLN‐βC) was prepared with glycerol monostearate (GMS) and stearic acid (SA) as wall materials; tween 80 (T₈₀) and soy lecithin (SL) as surfactant and co‐surfactant, respectively. To form nano emulsions, high shear homogenization was used. Further, the formed nano emulsion was freeze dried to get free flowing powder. The particle size of SLN‐βC and freeze dried SLN‐βC was found to be 836.90 and 974.30 nm, respectively. Encapsulation efficiency and loading capacity of freeze dried SLN‐βC was found to be 61.35 ± 1.18% and 12.85% respectively. SLN particles give sustained release of β‐carotene up to 24 hr. Further, in vitro simulated gastro intestinal studies confirmed the effective protection of encapsulated β‐carotene in gastric condition and its release in intestinal condition. Freeze dried SLN‐βC also showed better stability in terms of moisture content, color, rehydration time and powder flow properties during storage for one month. PRACTICAL APPLICATIONS: β‐carotene is an excellent antioxidant due to its high provitamin A activity. It is also used in various industrial food applications as a natural colorant as it gives good appeal to the product. However, it is hydrophobic and light sensitive. Therefore, encapsulation of β‐carotene can improve its stability by retaining its functional properties. This work confirms encapsulation using solid lipid matrix as a proficient method for retaining the functional properties of β‐carotene.

Temperature and Time Consolidation Effect on the Bulk Flow Properties and Arching Tendency of a Detergent Powder

AbstractTime consolidation flow properties of a commercial detergent powder were measured at different elevated temperatures with the Brookfield powder flow tester (PFT). A substantial increase of powder cohesion was observed at higher temperature and after time consolidation. The Jenike method for silo design was applied to correlate the powder time consolidation flow properties at elevated temperature to the critical outlet slot to attain an arch‐free silo. The dependence of the critical diameter on temperature and time consolidation was successfully described by the model.

Assessment of a powder rheometer equipped with a cylindrical impeller for the measurement of powder flow properties at low consolidation

A powder rheometer equipped with a cylindrical impeller was studied to assess whether it could be suitable to derive quantitative physical parameters of powder flow properties. The equipment used in was the Powder Cell unit purposely developed by Anton Paar to fit on Anton Paar MCR Rheometers and to carry out torque measurements on aerated and not aerated powders. In this instrument, the state of consolidation of the powder can be adjusted by changing the impeller depth and the aeration rate, and very low consolidation stresses can be achieved. A cylindrical impeller geometry was tested on free flowing and easy flowing powders. A simple model was developed to relate the measured torque with the effective angle of internal friction in the powder measured with a standard powder shear tester. The results indicated the clear relationship between the effective angle of internal friction and the measured torque. The inversion of the calculation procedure highlighted that the Couette system does not always allow estimating the effective angle of internal friction reliably. In fact, small experimental error in the torque measurement may lead to large changes of the estimated effective angle of internal friction.