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David Pearce - One of the best experts on this subject based on the ideXlab platform.
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effect of surface composition on the Flowability of industrial spray dried dairy powders
Colloids and Surfaces B: Biointerfaces, 2005Co-Authors: Xiao Dong Chen, David PearceAbstract:The surface composition of four industrial spray-dried dairy powders (skim milk powder, whole milk powder, cream powder and whey protein concentrate) was estimated by electron spectroscopy for chemical analysis (ESCA), and its influence on powder Flowability was studied. It was found that skim milk powder flows well compared to the other powders because the surface is made of lactose and protein with a small amount of fat, whereas the high surface fat composition inhibits the flow of whole milk, cream and whey protein powders. However, the poor Flowability of the powders with high surface fat coverage was drastically improved by removal of fat present on the surface through a brief wash with petroleum ether. The results obtained indicate that, although there are several parameters including particle size, which influence the Flowability of powders, the Flowability of powders is strongly influenced by the surface composition of powders, particularly for fat-containing powders.
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Effect of surface composition on the Flowability of industrial spray-dried dairy powders
Colloids and Surfaces B: Biointerfaces, 2005Co-Authors: Esther H.-J. Kim, Dong Chen Xiao, David PearceAbstract:The surface composition of four industrial spray-dried dairy powders (skim milk powder, whole milk powder, cream powder and whey protein concentrate) was estimated by electron spectroscopy for chemical analysis (ESCA), and its influence on powder Flowability was studied. It was found that skim milk powder flows well compared to the other powders because the surface is made of lactose and protein with a small amount of fat, whereas the high surface fat composition inhibits the flow of whole milk, cream and whey protein powders. However, the poor Flowability of the powders with high surface fat coverage was drastically improved by removal of fat present on the surface through a brief wash with petroleum ether. The results obtained indicate that, although there are several parameters including particle size, which influence the Flowability of powders, the Flowability of powders is strongly influenced by the surface composition of powders, particularly for fat-containing powders. © 2005 Elsevier B.V. All rights reserved.
Wolfgang Peukert - One of the best experts on this subject based on the ideXlab platform.
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A novel process for production of spherical PBT powders and their processing behavior during laser beam melting
2016Co-Authors: Jochen Schmidt, Marius Sachs, Karl-ernst Wirth, Meng Zhao, Stephanie Fanselow, Katrin Wudy, Maximilian Drexler, Dietmar Drummer, Wolfgang PeukertAbstract:Additive manufacturing processes like laser beam melting of polymers are established for production of prototypes and individualized parts. The transfer to other areas of application and to serial production is currently hindered by the limited availability of polymer powders with good processability. Within this contribution a novel process route for the production of spherical polymer micron-sized particles of good Flowability has been established and applied to produce polybutylene terephthalate (PBT) powders. Moreover, the applicability of the PBT powders in selective laser beam melting and the dependencies of process parameters on device properties will be outlined. First, polymer micro particles are produced by a novel wet grinding method. To improve the Flowability the produced particles the particle shape is optimized by rounding in a heated downer reactor. A further improvement of Flowability of the cohesive spherical PBT particles is realized by dry coating. An improvement of Flowability by a fa...
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A novel process chain for the production of spherical sls polymer powders with good Flowability
Procedia Engineering, 2015Co-Authors: Jochen Schmidt, Christina Blümel, Marius Sachs, Karl-ernst Wirth, Franziska Toni, Bettina Winzer, Wolfgang PeukertAbstract:Rapid prototyping has been applied so far in the production of special parts at low piece numbers. Currently, rapid prototyping gradually is transferred to additive manufacturing opening new applications. Especially selective laser sintering (SLS) applying polymer powder systems is promising. In the case of SLS basically only polyamide is available as an optimized powder material showing satisfying behavior during processing. Other types of polymer powders produced by cryogenic grinding show poor powder Flowability as well as an unfavorable particle habitus resulting in poor device quality. In fact, it is challenging to produce laser sintering powders with small particle size, good Flowability and processability. Within this account we present a novel process route for the production of spherical polymer micron-sized particles of good Flowability. The feasibility of the process chain is demonstrated for polystyrene (PS) and poly butylene terephthalate (PBT) and the increase of powder Flowability after the consecutive process steps has been monitored using a tensile strength tester. The influence of particle habitus and surface functionalization on powder Flowability and its properties is discussed. In a first step polymer microparticles are produced by a wet grinding method at reduced temperatures. By this approach the mean particle size and the particle size distribution can be tuned between a few microns and several 10 microns and adapted to specific needs. The dependencies of mean product particle size, particle size distribution and grinding kinetics on stressing conditions, system composition and especially process temperature (increase of the brittleness of the polymer vs. increase of dampening of grinding bead motion with decreasing temperature) will be extensively discussed for the polymers PS, PBT, poly oxo methylene (POM) and Poly ether ether ketone (PEEK). The comminution products obtained typically consist of microparticles of irregular shape and poor powder Flowability, i.e. these intermediate products are cohesive and thus will show poor SLS processability. An improvement of Flowability of the ground polymer particles is achieved in a second step by changing their shape. The irregular particles are rounded using a heated downer reactor. It will be demonstrated that the 'degree' of rounding can be controlled by changing the temperature profile or the residence time. To further improve the Flowability of the cohesive spherical polymer microparticles nanoparticles are adhered to the microparticles' surface in a third step. The improvement of powder Flowability after the consecutive process steps is remarkable: rounded and dry-coated PS powders exhibit a strongly reduced tensile strength (by a factor 5) in comparison to the tensile strength of the edged PS comminution product. The improved Flowability and packing behavior of the polymer powders open new options in SLS processing including the usage of much smaller polymer beads.
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a novel process route for the production of spherical lbm polymer powders with small size and good Flowability
Powder Technology, 2014Co-Authors: Jochen Schmidt, Christina Blümel, Marius Sachs, Karl-ernst Wirth, Franziska Toni, Bettina Winzer, Wolfgang PeukertAbstract:Abstract Rapid prototyping has been applied so far in the production of special parts at low piece numbers. Currently, ‘rapid prototyping’ gradually is transferred to additive manufacturing opening new applications. At present basically only polyamide (PA) is available as an optimized powder material showing satisfying behavior during processing in laser beam melting (LBM). Other types of polymer powders produced by cryogenic grinding show poor powder Flowability as well as an unfavorable particle habitus resulting in poor device quality. In fact, it is challenging to produce laser sintering powders with small particle size, good Flowability and processability. We present a novel process chain for the production of spherical polymer micron-sized particles of good Flowability that can be applied to a large variety of polymers: in a first step polymer particles are produced by a wet grinding method that are rounded in a second step using a heated downer reactor. To increase the Flowability of the cohesive spherical polymer particles further nanoparticles are adhered to the particle surface in the third step. We demonstrate an increase of powder Flowability by a factor of 5. The influence of particle habitus and nanoparticle functionalization on powder Flowability is discussed in detail.
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A novel process route for the production of spherical LBM polymer powders with small size and good Flowability
Powder Technology, 2014Co-Authors: Jochen Schmidt, Christina Blümel, Marius Sachs, Karl-ernst Wirth, Franziska Toni, Bettina Winzer, Wolfgang PeukertAbstract:Rapid prototyping has been applied so far in the production of special parts at low piece numbers. Currently, 'rapid prototyping' gradually is transferred to additive manufacturing opening new applications. At present basically only polyamide (PA) is available as an optimized powder material showing satisfying behavior during processing in laser beam melting (LBM). Other types of polymer powders produced by cryogenic grinding show poor powder Flowability as well as an unfavorable particle habitus resulting in poor device quality. In fact, it is challenging to produce laser sintering powders with small particle size, good Flowability and processability. We present a novel process chain for the production of spherical polymer micron-sized particles of good Flowability that can be applied to a large variety of polymers: in a first step polymer particles are produced by a wet grinding method that are rounded in a second step using a heated downer reactor. To increase the Flowability of the cohesive spherical polymer particles further nanoparticles are adhered to the particle surface in the third step. We demonstrate an increase of powder Flowability by a factor of 5. The influence of particle habitus and nanoparticle functionalization on powder Flowability is discussed in detail. © 2014 Elsevier B.V.
Yushi Feng - One of the best experts on this subject based on the ideXlab platform.
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massing in high shear wet granulation can simultaneously improve powder flow and deteriorate powder compaction a double edged sword
European Journal of Pharmaceutical Sciences, 2011Co-Authors: Yushi FengAbstract:The influence of massing during high shear wet granulation (HSWG) process on granule properties and performance was investigated using microcrystalline cellulose (MCC). Massing time varied from 0 to 40 min while other factors were fixed. Granule physical properties, including morphology, size, porosity, and specific surface area (SSA), were characterized. Changes in powder properties were profound in the first 10 min of massing but negligible beyond 10 min. With 10 min of massing, granule tabletability decreased by 75% while Flowability increased by 75%. The significantly deteriorated tabletability and improved Flowability resulted from dramatic changes in granule morphology, porosity, and SSA. The results confirm that massing time is a key process parameter in HSWG, and it must be carefully evaluated and controlled during process development, scale up, and manufacturing.
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origin of profound changes in powder properties during wetting and nucleation stages of high shear wet granulation of microcrystalline cellulose
Powder Technology, 2011Co-Authors: Yushi FengAbstract:Abstract The aim of this work was to understand the evolution of powder tabletability and Flowability during wetting and nucleation stages of high-shear wet granulation (HSWG). Microcrystalline cellulose (MCC) was granulated with water using a high-shear process. Granule morphology, surface texture, size, porosity, specific surface area, tabletability, and Flowability were characterized. MCC granulated with 5% water showed no change in tabletability but significantly improved Flowability, corresponding to smoother surfaces and lower surface area. From 5% to 25% water, tabletability decreased by 1/4 but Flowability remained unchanged. Granule shape and porosity remained unchanged while surfaces were smoothened, leading to decreased surface area. From 25% to 35% water, MCC granules became more round. There was another sharp decrease in tabletability but powder Flowability remained unchanged. Forty-five percent of water led to more particle rounding and commencement of nucleation, which only slightly impacted tabletability and Flowability. From 0% to 45% water, granule size decreased slightly and could not explain the significant changes in powder tabletability and Flowability. Deteriorated tabletability was instead caused by surface smoothing, granule densification, and granule rounding. Enhanced powder Flowability was caused mostly by surface smoothing with granule rounding as a minor contributor.
Mehmet Ali Tasdemir - One of the best experts on this subject based on the ideXlab platform.
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mechanical behaviour and fibre dispersion of hybrid steel fibre reinforced self compacting concrete
Construction and Building Materials, 2012Co-Authors: Burcu Akcay, Mehmet Ali TasdemirAbstract:Abstract In this study, mixture design, workability, fibre dispersion/orientation, mechanical properties and fracture behaviour of hybrid steel fibre reinforced self-compacting concretes (HSFRSCCs) were investigated. Three different types of steel fibres with and/or without hooked-ends were added to the mixtures in two different volume fractions (0.75 and 1.5% of the total volume of concrete). The results of slump flow, U-box, V-funnel and J-ring tests have shown that increasing the fibre content of the concretes slightly reduced the workability of HSFRSCC, and the main influencing factor on Flowability is the geometry of fibres. The addition of fibres, although did not change the final Flowability, decreased the rate of Flowability. The results from the experimental tests showed that the flexural strengths increased slightly with increasing strength of long fibres, whereas the splitting tensile strength remained unchanged. The concretes with high strength, long steel fibres show behaviour of enhanced toughness and ductility compared to that with normal strength steel fibres. The orientation and distribution of fibres in concrete have been investigated by image analysis and it was observed that fibres dispersed homogeneously in all concrete series without any clumping. With increasing the amount of fibres, the fibres were more vertically orientated relative to the bending loading direction, resulting in enhancement in the mechanical properties of concrete.
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Mechanical behaviour and fibre dispersion of hybrid steel fibre reinforced self-compacting concrete
Construction and Building Materials, 2012Co-Authors: Burcu Akcay, Mehmet Ali TasdemirAbstract:In this study, mixture design, workability, fibre dispersion/orientation, mechanical properties and fracture behaviour of hybrid steel fibre reinforced self-compacting concretes (HSFRSCCs) were investigated. Three different types of steel fibres with and/or without hooked-ends were added to the mixtures in two different volume fractions (0.75 and 1.5% of the total volume of concrete). The results of slump flow, U-box, V-funnel and J-ring tests have shown that increasing the fibre content of the concretes slightly reduced the workability of HSFRSCC, and the main influencing factor on Flowability is the geometry of fibres. The addition of fibres, although did not change the final Flowability, decreased the rate of Flowability. The results from the experimental tests showed that the flexural strengths increased slightly with increasing strength of long fibres, whereas the splitting tensile strength remained unchanged. The concretes with high strength, long steel fibres show behaviour of enhanced toughness and ductility compared to that with normal strength steel fibres. The orientation and distribution of fibres in concrete have been investigated by image analysis and it was observed that fibres dispersed homogeneously in all concrete series without any clumping. With increasing the amount of fibres, the fibres were more vertically orientated relative to the bending loading direction, resulting in enhancement in the mechanical properties of concrete. © 2011 Elsevier Ltd. All rights reserved.
Shuji Matsusaka - One of the best experts on this subject based on the ideXlab platform.
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Effect of particle size distribution on Flowability of granulated lactose
Advanced Powder Technology, 2019Co-Authors: Yozo Kudo, Masatoshi Yasuda, Shuji MatsusakaAbstract:Abstract The Flowability of powders used in tableting significantly affects tablet weight and content uniformity of active pharmaceutical ingredients. Use of granulated materials instead of powdered materials can improve Flowability. In this study, the effect of particle size distribution on Flowability of granulated lactose was quantitatively analyzed. Three types of granulated lactose were classified into progressively narrower size fractions, and nine samples were systematically prepared. The mass median diameters were nearly constant (i.e., 130.5 ± 13.5 μm) and the geometric standard deviations ranged from 1.29 to 2.04. Two flow properties (angle of repose and compressibility) were measured. The correlations between flow properties and the particle size distributions were analyzed, and the coefficients of determination were obtained for different particle diameters and cumulative mass fractions. The optimal conditions to maximize the coefficients of determination were defined. Furthermore, static and dynamic friction properties were evaluated, and their correlations with particle size distribution were calculated.
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a new method for evaluating powder Flowability using constant volume shear tester
Advanced Powder Technology, 2018Co-Authors: Yasuhiro Shimada, Shigenobu Hatano, Shuji MatsusakaAbstract:Abstract This is an article translated from the original version published in the Journal of the Society of Powder Technology, Japan. A new method for evaluating powder Flowability is developed using a constant-volume shear tester; this tester measures the upper and lower normal stresses and the shear stress acting on a powder bed. A single shear test provides a series of characteristics, such as the powder yield locus (PYL), consolidation yield locus (CYL), critical state line (CSL), shear cohesion, stress relaxation ratio, stress transmission ratio, and void fraction. The values of shear stress as a function of the normal stress and void fraction are visualized in three-dimensional diagrams. Furthermore, powder Flowability is evaluated using a flow function obtained from the PYL.
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effect of particle shape on powder Flowability of microcrystalline cellulose as determined using the vibration shear tube method
International Journal of Pharmaceutics, 2014Co-Authors: Takehiko Horio, Masatoshi Yasuda, Shuji MatsusakaAbstract:Abstract Powder Flowability of microcrystalline cellulose particles having different particle shapes, whose aspect ratios ranged from 1.8 to 6.4, was measured using the vibration shear tube method. Particles lubricated with magnesium stearate were also investigated in order to evaluate the effect of surface modification on powder Flowability. Particles were discharged through a narrow gap between a vibrating tube edge and a flat bottom surface, where each particle experienced high shear forces, thus, overcoming adhesion and friction forces. Vibration amplitude was increased at a constant rate during measurement and the masses of the discharged particles were measured at consistent time intervals. Flowability profiles, i.e., the relationships between the mass flow rates of the discharged particles and their vibration accelerations, were obtained from these measurements. Critical vibration accelerations and characteristic mass flow rates were then determined from Flowability profiles in order to evaluate static and dynamic friction properties. The results were compared with those obtained using conventional methods. It was found that angle of repose and compressibility were related to static and dynamic friction properties. Furthermore, it was found that particle aspect ratio more significantly affects powder Flowability than does lubrication with magnesium stearate.
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development of measurement system for powder Flowability based on vibrating capillary method
Powder Technology, 2009Co-Authors: Yanbin Jiang, Shuji Matsusaka, Hiroaki Masuda, Yu QianAbstract:Abstract An automatic measurement system for evaluating powder Flowability based on the vibrating capillary method has been studied experimentally. The vibration amplitude was controlled by a computer, and the vibration acceleration and the mass of particles discharged from the capillary were obtained by digital processing. The measurement time was 2 min and the amount of the powder required for each measurement was less than a few grams. To characterize the dynamic powder Flowability, evaluation factors were developed. A series of experiments was conducted using powders with mass median diameters from 5.2 to 58.2 μm, showing that this measurement system can fully evaluate the powder Flowability.
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evaluation of Flowability of composite particles and powder mixtures by a vibrating capillary method
Journal of Chemical Engineering of Japan, 2006Co-Authors: Shuji Matsusaka, Yanbin Jiang, Hiroaki Masuda, Toyokazu YokoyamaAbstract:Flowability of micrometer-sized particles treated with nanometer-sized particles has been studied by a vibrating capillary method. Two different types of treatments, i.e. dry particle coating based on the mechanofusion and simple mixing through shaking manually, were adopted to prepare composite particles and powder mixtures, respectively. The micrometer-sized core particle was polymethylmethacrylate (PMMA), and the coating nano-particles were TiO2, Al2O3, or SiO2. Surface morphology of the treated particles was analyzed by digital processing of SEM photographs, and flow behavior of powders in the vibrating capillary tube was studied with particular attention to the effects of the kind of nano-particles, its concentration, and the treatment method. Two factors were introduced to evaluate the Flowability; one is the critical amplitude of vibration making the powder flow, and the other is the mass flow rate as a function of the vibration amplitude. The experimental results showed that the mechanofusion treatment gave a remarkable improvement in the powder Flowability evaluated by the two factors mentioned above. The general tendency of the improvement can be explained by the projected-area ratio defined as the ratio of the total projected-area of nano-particles adhering to core-particle surface and the projected-area of the core-particle itself.