Hausner Index Research Articles

The study of the influence of pharmacotechnological and economic factors on the pharmaceutical development of capsules with trimetazidine for the treatment of cardiovascular diseases

Cardiovascular diseases are the main cause of reduced life expectancy and quality in the modern world. Aim. To study the influence of pharmacotechnological and economic factors on the pharmaceutical development of capsules with trimetazidine for the treatment of cardiovascular diseases. Materials and methods. The research material was the medicinal substance trimetazidine (SharonBio-Medicine Ltd., India), excipients used in the technology of solid dosage forms. The study of pharmacotechnological characteristics was carried out on devices of the company “Pharma Test” (Germany). The fluidity and the angle of repose were measured on a VP-12A device. The fluidity was estimated by the Carr Index of powder compressibility and the Hausner Index coefficient. A comparative analysis of the cost calculation of the production of drugs with trimetazidine in tablet and capsulated forms was carried out using the “costs plus” method. Results and discussion. As a result of the studies conducted on the selection of excipients for capsules with trimetazidine, the following excipients were reasonably used: lactose monohydrate 200/25 diluent, mannitol PARTECK M 200 filler and CompactCel®MAB mixture of a disintegrant, a moisture regulator and a lubricant. A comparative analysis of the cost calculation of the production of drugs with trimetazidine in tablets and capsules was carried out. Conclusions. The advantages of direct encapsulation technology by economic and technological indicators prove the economic efficiency and contribute to new developments of high-quality medicinal products in capsules with high efficiency, availability and ease of use.

Formulation of anti-malaria capsules based on the fruit of Picralima nitida (Stapf) T. Durand and H. Durand (Apocynaceae

Malaria is a parasitic disease that is widely spread throughout the world. The annual number of cases is estimated at around 500 million; the African continent is the most affected, accounting for 95% of cases. For the treatment, WHO recommends artemisinin-based combinations; unfortunately, the cost of these combinations is relatively high, making them difficult to afford. This justifies the search for new antimalarial drugs. A large number of plant species in Cameroon have been identified as anti-malarial medicinal plants. Picralima nitida is one of the plants traditionally used to treat malaria in traditional medicine, and its in vitro and in vivo antimalarial activity and toxicological profile have already been scientifically demonstrated. The aim of the present study was to formulate capsules based on the aqueous extract of Picralima nitida fruit, in an attempt to rationalize its use in the treatment of malaria. The aqueous extract of Picralima nitida fruit was prepared by maceration and then stabilized; its physicochemical characteristics were determined. The daily quantity of extract required for the treatment of malaria was determined in milligrams of total alkaloids. Finally, the extract was stabilized before being filled into capsules using European pharmacopoeia techniques. The capsules were also tested according to European Pharmacopoeia 11th edition techniques. The extract was obtained in 6.25% yield. The extract was soft, hygroscopic, brown in color, very bitter in flavor and caramel in odor. The following phytochemical groups were present in the extract: alkaloids, phenolic compounds, flavonoid tannins, anthocyanins, saponins, terpenes, sterols. Total alkaloid content was 0.11g per gram of extract. To stabilize the extract and make it suitable for capsule filling, 25% colloidal silica and 13% microcrystalline cellulose were added. The stabilized extract showed good flowability (flow time 6s, Carr index 11.8% and Hausner index 1.13), a moderately fine powder texture (d50 < 300um) and homogeneous distribution. The daily dose determined for a 60 kg adult was 3900mg of extract, corresponding to 313 mg of total alkaloids, which could be divided into 8 N°0 or 12 N°00 capsules. On inspection, the capsules were found to comply with the requirements of the 11th edition of the European Pharmacopoeia. The characteristics of the formulated capsules are favorable to make them a good candidate for the various phases of clinical trials with a view to making them an improved traditional medicine (ITM)

Modification of Bulk Density, Flow Property and Crystallinity of Microcrystalline Cellulose Prepared from Waste Cotton.

The most affordable type of tablet is the immediately compressible tablet, which uses microcrystalline cellulose (MCC), a popular pharmaceutical excipient, as a filler or binder. To make it compatible with different active drugs and excipients, we tried to change some physical properties of the MCC. In the current study, we used a chelating agent to pretreat the waste cotton before pulping, bleaching, and finally, hydrochloric acid degradation with a concentration of 2N at 100 °C temperature for 20 min to prepare MCC. The prepared MCC was treated with different concentrations of sodium hydroxide at room temperature or at -20 °C followed by precipitation with hydrochloric acid or ethanol with complete washing with distilled water till neutralization. Evaluation of the degree of polymerization (DP) and FT-IR spectrum confirm the identity of the microcrystalline cellulose. The DP was found to be 216. The bulk density of the unmodified MCC was 0.21 while that of modified MCC varied from 0.253 to 0.594. The modified MCC powder showed good flow properties compared to the unmodified MCC as evaluated by the Hausner index, Carr's index and the angle of repose. The scanning electron microscopy (SEM) of the MCC revealed that the rod shape has been changed to an oval shape due to treatment with sodium hydroxide at -20 °C. The X-ray crystallographic (XRD) analysis indicated that the unmodified MCC and standard MCC showed the crystallinity index (CrI) value of 86.82% and 87.63%, respectively, while the value ranges from 80.18% to 60.7% among the modified MCC powder. The differences in properties of the MCC might be due to the variation of rearrangement of the cellulose chain among the MCC particles due to treatment with different concentrations of a base at different temperatures and precipitation environments. This has enabled us to prepare MCC with different properties which might be compatible with different drugs.

PREPARATION OF MICROCRYSTALLINE CELLULOSE FROM DISSOLVING CELLULOSE OBTAINED FROM JUTE FIBERS AND ITS APPLICATION IN THE FORMULATION OF FEXOFENADINE HYDROCHLORIDE TABLET DOSAGE FORM

Introduction: The most affordable tablet form is microcrystalline cellulose (MCC), a popular pharmaceutical excipient that is utilized as a filler or binder in immediately compressible tablets. Methods: In the present study, we extracted dissolving cellulose from jute fibers by treatment with 0.1 N hydrochloric acid solution and 20% w/w sodium hydroxide solution at high temperature and pressure. The dissolving cellulose was subjected to acid hydrolysis at 100 0C for 2 h with 2 N hydrochloric acid. The identity of the MCC was confirmed by FT-IR and by determining the degree of polymerization. To evaluate the flow property, we determined the bulk, density, tapped density, Hausner index, Carr’s index and angle of repose. The tableting property of the prepared MCC was evaluated by making fexofenadine hydrochloride tablets.
 Result and Discussion: The dissolving cellulose contains 94.67% α-cellulose The DP of the MCC was found 191. The powder properties such as bulk density, tapped density, Hausner index and Carr’s index, angle of repose values are comparable with that of standard Avicel PH102. The hardness, friability, disintegration time and % dissolved in 30 minutes were dissolution value of the tablets 5.6 kg, 0.34%, 178.17 sec and 83.89%, respectively. All these values are within the United State Pharmacopoeia range and are comparable with the tablets prepared from Avicel PH102 and marketed fexofenadine tablets.

Extraction and Characterization of Pharmaceutical Grade Microcrystalline Cellulose From Bambara Nut (Voandzeia Subterranean (L) Thousars) Husk

Microcrystalline cellulose is a vital ingredient in the food, pharmaceutical, and cosmetics industries. In this study, Bambara nutshell microcrystalline cellulose (BNS-MCC) was prepared by acid hydrolysis modification of Bambara nutshell alpha-cellulose pulp. The sample was subjected to sodium hydroxide pulping (2.0% and 17.5% NaOH respectively) and a multistage pulping treatment using 3.5% nitric acid. The analysis results showed that the pulping method was effective for substantial removal of lignin with a 14.416% yield of alpha-cellulose pulp. The organoleptic and physicochemical properties of BNS-MCC were examined. The prepared BNS-MCC powder was examined using a Scanning Electron Microscope (SEM), Fourier Transform Infrared spectroscopy (FTIR), and X-ray Diffractometer (XRD). The sample’s powder flow properties (true density, Hausner index, Carr’s index, angle of repose,powder porosity, loss on drying, and moisture sorption capacity) were (1.216g/mL, 1.34, 25.75%, 39.80o, 64.7%, and 46.81%). The results of the analysis of the BNS-MCC compared well with commercial grades and conformed to US Pharmacopeia (USP) and British Pharmacopeia specifications. This result shows that Bambara nutshells have potential application for pharmaceutical grade cellulose production used in direct compression tableting.

PEMBUATAN MIKROKRISTALIN SELULOSA (MCC) dari BATANG PISANG MAS (Musa acuminata colla) dengan AVICEL PH 102 SEBAGAI PEMBANDING TAHUN 2019

Commercial cellulose microcrystalline known as Avicel PH 102, which is a tablet filling material Avicel PH 102 which is expensive and uses a lot of it, it is necessary to look for other alternative sources of producing microcrystalline cellulose. The Waste of banana stem contains water content of 80-90%, cellulose 63-64%, hemicellulose 20%, and lignin 5% and contains 11-12% other constituens so that it can be the basic material for making MCC. This study aimed to isolate α-cellulose from banana mas stems and characterize microcrystalline cellulose with Avicel PH 102. The method of this study was an experimental. Microcrystalline banana stem cellulose is obtained by heating banana stem powder with 4% NaOH which serves to dissolve lignin, then bleached with 2.5% NaOCl, 17.5% NaOH heated to dissolve β-cellulose and γ-cellulose, and heated with HCL 2 N . The results are hydrolyzed with α-cellulose and then hydrolyzed with 2.5N HCl to give microcrystalline cellulose, which is characterized and compared to Avicel PH102. The result of characterization of banana mas stem microcrystalline cellulose and Avicel PH 102 which were obtained respectively is organoleptic tests of coarse powder, white, doesn’t have any smells; pH 6.6 and 6.5; solubility of substances in water 0.023 and 0.023%; total ash content are 0.17 and 0.12%; decrease of drying 5.47 and 5.28%; real density 0.337 and 0.404 g / cm3; true type weight 1.43 and 1.43 g / cm3; incompressible density 0.478 and 0.480 g / cm3; compressibility index 41.77 and 18.85%; Hausner index 1.41 and 1.18; porosity; 76.43 and 93.640%. Based on the results of the study concluded that microcrystalline cellulose can be made from banana mas stems and has the same characteristics as Avicel PH 102.

Formulation of Orally Disintegrating Tablets of Captopril as Superdisintegrant using Corncob (Zea mays L.)

AIM: This study aimed to make corncobs the basic material for the manufacture of microcrystalline cellulose. METHODS: Manufacture of corncob cellulose microcrystals (CCMs) by isolating alpha-cellulose from corncobs, then hydrolyzed with HCl 2.5 N. The yield of CCMs of 14.51% can be used as orally disintegrating tablet (ODT) and has similarities with Avicel as standard comparison. RESULTS: Both organoleptic results were pH 5.6 and 6.54; drying shrinkage 3.33% and 4.39%; total ash content 0.17% and 0.02%; and water solubility 0.9% and 0.12%. Furthermore, the real specific gravity is 0.317 and 0.306 g/cm3, incompressible density is 0.379 and 0.375 g/cm3, the true density is 1.291 and 1.206 g/cm3, Hausner index is 1.195 and 1.225, compressibility index is 19.55 and 22.55%, and porosity is 75.5 and 74.6%. CONCLUSION: Captopril ODT tablet preparations with CCM as filler have almost the exact tablet evaluation results compared to Avicel and to meet the requirements.

Effect of a cryogenic treatment in the microstructure, functional and flow properties of soy protein isolate

In this work, the impact of cryogenic treatment of soy protein isolate (SPI) on its microstructure, functional and flow properties was evaluated. SPI was treated with 96% ethanol, freezed in liquid nitrogen, and then lyophilized to obtain the modified soy protein isolate (MSPI). To analyze the changes in the surfaces of the SPI and MSPI particles, AFM images were taken. An adsorption isotherm was performed at 25 °C, then the surface fractal dimension and specific surface area were analyzed by water adsorption isotherm at 25 °C. Functional properties such as emulsion capacity, foam, oil and water absorption, gelling and viscosity were determined. Likewise, the flow properties of powders as bulk density, tapped density, particle density, Hausner index, compressibility index and porosity were determined. MSPI showed hollows in the surface, higher roughness (Rq) and higher specific surface area than SPI. Regarding functional properties, MSPI presented higher viscosity, oil and water absorption, emulsifying and gelling capacity than SPI. MSPI powders showed lees flowability than SPI. The results suggested that the application of a cryogenic treatment in SPI changes the microstructure and impacts on the functional and flow properties of SPI, since some functional properties were improved, such as gelation, viscosity, emulsifying, adsorption and absorption capacity; and the flow properties were modified.

Preparation of Co-Processed Excipients for Controlled-Release of Drugs Assembled with Solid Lipid Nanoparticles and Direct Compression Materials.

The purpose of the study was to develop a novel, directly compressible, co-processed excipient capable of providing a controlled-release drug system for the pharmaceutical industry. A co-processed powder was formed by adsorption of solid lipid nanoparticles (SLN) as a controlled-release film onto a functional excipient, in this case, dicalcium phosphate dihydrate (DPD), for direct compression (Di-Tab®). The co-processed excipient has advantages: easy to implement; solvent-free; industrial scaling-up; good rheological and compressibility properties; and the capability to form an inert platform. Six different batches of Di-Tab®:SLN weight ratios were prepared (4:0.6, 3:0.6, 2:0.6, 1:0.6, 0.5:0.6, and 0.25:0.6). BCS class III ranitidine hydrochloride was selected as a drug model to evaluate the mixture’s controlled-release capabilities. The co-processed excipients were characterized in terms of powder rheology and dissolution rate. The best Di-Tab®:SLN ratio proved to be 2:0.6, as it showed high functionality with good flow and compressibility properties (Carr Index = 16 ± 1, Hausner Index = 1.19 ± 0.04). This ratio could control release for up to 8 h, so it fits the ideal profile calculated based on biopharmaceutical data. The compressed systems obtained using this powder mixture behave as a matrix platform in which Fickian diffusion governs the release. The Higuchi model can explain their behavior.

Tablets Development Based on Clover Meadow Grass Phytosubstance Using Design of the Experiment Method and QdD Tools

Introduction . Quality, along with efficacy and safety, are the key characteristics of a drug. Therefore, it is important in frame of pharmaceutical development to lay the foundation for obtaining a quality product and achieving the desired product characteristics. One of the tools used for this is the «Quality by design» approach (QbD) - quality through development. The ICH Q8 «Pharmaceutical development» manual defines it as a systematic approach to development that starts with pre-defined goals and focuses on understanding the product and process, as well as managing the process based on reliable scientific data and quality risk management. Aim . The aim of the research is to develop the composition of tablets based on clover meadow grass phytosubstance using the QbD tool with application of mathematical model that links the composition of tablets (CMA) with its quality attributes (CQA). Materials and methods . The research was based on the concept of quality by design/quality through development. The main method for conducting the development process was design of experiments method/experiment planning with creating of individual design. The experiment planning was performed in the software package JMP Pro 14 (ver. 14. 3. 0), SAS Institute Inc., USA. The method of risk analysis-failure mode and effects analysis (FMEA)/analysis of the types and consequences of failures was used for risk assessment in research. As methods of analysis of the tablet mixture and the tablets were used the following the tests: disintegration of tablets, crushing strength of tablets, determination of hygroscopicity, determination of Carr's and Hausner index. Results and discussion . The composition of tablets based on the clover meadow grass phytosubstance obtained by direct pressing was developed. In order to develop the composition of tablets in accordance with the ICH Q8 guidelines, the first step was to create a quality target product profile. To ensure the properties specified in the quality target product profile, the component composition of the developed tablets was selected based on the selected production technology and key characteristics of both the tablet mixture and the finished product. The risk assessment for the product composition determined that the quantitative content of 4 excipients are considered as critical quality attributes of materials (CMA). CMAs affect the critical quality attributes (CQA) of the dosage form, which determine the effectiveness of the composition. Based on the initial data analysis, optimal content boundaries for each component were established. Potentially critical qualitative characteristics of the drug under development (CQA) were identified. A mathematical model linking critical quality parameters and tablet composition was obtained and analyzed. Conclusion . Based on a mathematical model, the optimal composition of tablet mixture and tablets obtained from it was determined. The tablets quality indicators corresponding to the selected composition were calculated, and the adequacy of the obtained model was evaluated by comparing calculated and real indicators. It is shown that the calculation error does not exceed 10 %, and the proposed optimization algorithm and the model derived from it can be successfully used to optimize the composition of tablets.

Microencapsulation of Rambutan Peel Extract by Spray Drying.

Microencapsulation of bioactive compounds (BC) from rambutan peel by spray drying using DE10 maltodextrin as encapsulating agent was performed. The optimal conditions for the ethanolic extraction of BC were 60 °C, with a time of 1 h, 55% aqueous ethanol and three extraction cycles. The best spray drying encapsulating conditions for BC and antioxidant capacity (AC) were: inlet temperature 160 °C, outlet temperature 80 °C, and 10% encapsulating agent concentration in the feeding solution (core:encapsulating agent ratio of 1:4). With these conditions, retention and encapsulation efficiencies obtained were higher than 85%, the water activity value, moisture content and Hausner Index were of 0.25 ± 0.01, 3.95 ± 0.10%, and 1.42 ± 0.00, respectively. The optimized powder presented good solubility and morphological properties, showing microcapsules without ruptures. Based on these results, microencapsulation by spray drying is a viable technique which protects BC of rambutan peel, facilitating its application in the food, pharmaceutical, and cosmetic industries.

A review: Pharmaceutical excipients of solid dosage forms and characterizations

Excipients play an important role in formulating dosage forms. Exertion is empowered to help manufacture, provide, or collect dosage forms. Although considered pharmacological, excipients may consider a drug, due to chemical or physical interactions with the composition of the drug. Excipients have many functions in pharmaceutical dosage forms, including enhancing active ingredients in dosage forms, assisting active ingredients, disintegration, lubricants, binders, and suppliers. Each excipient has different characteristics. In this review, a library of studios is provided relating to the function, function, and content of solid excipients in a solid sedan. Various choices can be used on different compositions; resulting, this difference is also different. In this example, describe the types of excipients that can be used for various components in solid preparations that can be used in the formulation of solid preparations and select the right type of excipient according to the character of the desired solid preparation. In this review also presented a method, combining in and characterizing solid excipients to see the quality. The most commonly used methods for analysis of solid excipients are flow properties, compressibility index, Hausner index ratios, and angle of repose, while the instrumentation commonly used is Fourier transform infrared spectroscopy (FTIR), H and C-Nucleo magnetic resonance (H-CNMR), Scanning electron microscopy (SEM), Particle size analysis (PSA), X-ray diffraction (XRDP) and Differential scanning calorimeter (DSC).

Study of the fractional composition of granulate influence on the performance indicators of tablets based on salmonellosis bacteriophag

The author presented experimental data on the influence of technological factors on the quality indexes of tablets based on a cryoliofilized salmonella bacteriophage. The analysis of the technological properties of model granules with such parameters as bulk density, flow ability, vibration compacting index, Hausner index, Сarr's index showed that the fractional composition of the granules should contain no more than 33 % of the pulverized fraction (0,25 mm or less). The granulate, regardless of its fractional composition, has elastic-plastic properties characterizing the strength of the tablets. The influence of the pressing pressure of the cryoliofilized composition tablets with salmonella bacteriophage on the crush strength and disintegration of enteric-soluble tablets was studied. The optimum compression pressure of tablets within 60 mPa of granules with a content of pulp fraction (0.25 mm or less) is not to be higher than 33 %.

Obtención, separación y purificación de almidón a partir de Colocasia esculenta para su uso como excipiente en formas farmacéuticas

Taro (Colocasia esculenta) is a food grade product that has a considerable amount of starch, which offers great versatility of applications at low cost. It can be used in different types of industries and has many applications. In this paper the starch extracted from C. esculenta was used with the purpose of evaluating its binding capacity as an alternative to be used in the preparation of solid pharmaceutical forms (tablets) in comparison with potato starch. The starches extracted from taro and potato were tested for identity: percentage of humidity, pH and particle size; as well as rheological tests: flow velocity, resting angle, bulk density, compacted density and Hausner index. Tablets with taro starch and potatoes were made, to measure its hardness, weight, diameter, thickness and disintegration time. To establish the differences between the groups of tablets (taro, potato and commercial acetylsalicylic acid -Aspirin- as control), an ANOVA and Tukey post hoc test were performed. It is concluded that the starch extracted from the C. esculenta flour can be used as an excipient in the manufacture of tablets.

Encapsulation of Natural Antioxidant Compounds from Culinary Banana by Cocrystallization

The natural antioxidant obtained from both pulp and peel of culinary banana at various concentrations was encapsulated by cocrystallization in supersaturated sucrose solution. The encapsulated cocrystals led to higher entrapment yield of 75–80% in all samples. The HPLC chromatographs showed presence of major phenolic compounds in all the cocrystals. The angle of repose and Hausner index were found between 40°–44° and 0.98°–1.06°, respectively. The high solubility, low water activity and hygroscopicity indicated high stability and good handling properties. Fourier transform infra-red studies indicated that the functional groups present in cocrystals are typical bands of sucrose molecules. The differential scanning calorimetric thermographs confirmed two major endothermic peaks at 191.46 and 225.26C. Similarly, X-ray diffraction pattern showed the similar type of X-ray crystalline pattern of sucrose. The scanning electron microscopy showed well-defined cubic crystals with irregular cavities between them. The results of present investigation have credence to value addition of natural antioxidant for formulation of functional foods. Practical Applications Health consciousness and healthier food products are becoming important factors over the last few years which are driving the food market. One of the greatest challenges that food research is facing in this century lies in maintaining sustainable food production and at the same time delivering high quality food products with an added functionality to prevent life-style related diseases such as, cancer, obesity, diabetes, heart disease, stroke, etc. The incorporation of bioactive compounds into food products provides many advantages in food preservation and contributes to the development of functional foods. Looking at the present scenario of bioavailability of polyphenols and antioxidants, encapsulation technology becomes an actual choice and is a promising technique that can solve the disadvantages of the use of bioactive compounds as food additives.

Extraction and characterization of microcrystalline cellulose obtained from the back of the fruit of Lageriana siceraria (water gourd)

Article history: The work was aimed to investigate the suitability of acid modified alpha cellulose obtained from the back of the fruit of Lageriana siceraria (water gourd) in production of pharmaceuticals, particularly solid dosage forms. Cellulose is the commonest Filler/Binder or disintegrant used in tablet formulation. Cellulose was extracted from the fruit of Lageriana siceraria and subjected to modification by controlled acid micronisation to produce microcrystalline cellulose (LS-MCC) using 2.5N hydrochloric acid and Avicel pH 101 was used as the basis for comparison. The powder and flow properties of the microcrystalline cellulose was investigated and the result of both the LS-MCC and Avicel pH 101compared. Microcrystalline cellulose (LS-MCC) displayed superior swelling and hydration capacities as compared to Avicel PH101 but lesser flow properties in view of its higher angle of repose, Carr's and Hausner's index.

Optimization of parameters of the SeDeM Diagram Expert System: Hausner index (IH) and relative humidity (%RH)

As a methodology for characterizing substances in relation to their viability in direct compression, the SeDeM Diagram Expert System may be considered an open system in terms of the number of parameters applied and the optimization of these parameters. With the experience acquired from applying the SeDeM Diagram, in this study, we propose optimizing the parameters corresponding to the Hausner index (IH) and relative humidity (%HR) in order to simplify the mathematical calculation, so that it provides reliable data that can be extrapolated. The proposed optimization does not involve a conceptual change in the parameters considered nor a significant change in the results obtained compared with the previous calculation methodology initially established for the SeDeM Diagram Expert System, which means that the conclusions obtained by applying this method are equivalent.

Behavior and fluidization of the cohesive powders: agglomerates sizes approach

This work focuses on the fluidization of three types of TiO2 powders: Anatase (99% TiO2), Rutile 1 (95% TiO2 and 5% Al) and Rutile 2 (96.5% TiO2 and 3.5% Al and Si); the average diameters of the powders are 204 nm, 159 nm and 167 nm, respectively. These powders belong to group C of the Geldart classification and are characterized as cohesive powders with a non-free flow and a difficult fluidization. The fluidization of the powders was carried out in a glass column of 103 mm inner diameter and 1500 mm height. The experiments and analysis performed included measurements of the physical properties of the powders such as the particle size, density, specific surface area and the flow properties of the powders like the Hausner's index, the angle of repose, the angle of slide, consolidation and shearing (via shear cell testing). The results obtained with the nanometric TiO2 powders show a more complex behavior than the micronic powders; with a low strength value (Hausner index, angle of repose and angle of slide), the TiO2 powders have a free flow or intermediate-flow and a non-free-flow for higher strength intensities (consolidation and shearing). This behavior is related to the structure of the nanometric particles in the packed bed; the evolution of this structure is made up of individualized and spherical agglomerate shapes and is not perturbed by stresses of low intensities. Indeed, the latter seems to modify the structure of the powder (group C of Geldart classification) to acquire a behavior typical of group A, B or D in the Geldart classification. With high stress values, the individualized agglomerates are disintegrated and the powder is reduced to a more compact structure. The fluidization of TiO2 powders seems to evolve in a more homogeneous way than the micronic powders. This behavior is related to the initial structure being made up of stable agglomerates. Thus, this fluidization is made by agglomerates with a gas velocity of 3×10(6) to 4.6×10(6) times the gas velocity for fluidizing the primary particles.A numerical approach based on a force balance in agglomerating fluidized beds was developed in order to estimate the agglomerates sizes.

Study and comparison of micronic and nanometric powders: Analysis of physical, flow and interparticle properties of powders

This work concerns the study of the experimental and theoretical behavior of cohesive powders and in particular the comparison of two categories of powders: micronic and nanometric size particles. The latter, seem to be more complex and do not present the same behavior as the micronic powders under the action of the external forces. The examples used here are for the behavior of two micronic alumina powders of 3 µm and 13 µm average diameter and three nanometric powders of TiO 2 of 204 nm, 159 nm and 167 nm average diameter were examined. These powders belong to the group C of Geldart's classification [D. Geldart, Types of gas fluidisation, Powder Technology 7 (1973) 285–292] characterized as being cohesive powders with a non-free flow and difficult to fluidize. The physical properties of alumina and TiO 2 such as particle size, shape factor and density were analyzed rigorously to reach the measurements of the primary size and not of the agglomerate. The flow properties of the powders were characterized by measurements of the Hausner index, angle of repose, angle of slide, consolidation and shearing. The contact properties (interparticle energy) between particles were analyzed by a microscopic approach. The results suggest a more complex behavior of nanometric powders (TiO 2) than that of the micronic powders. The calculation and the analysis of the particulate interactions enabled us to correlate the degree of cohesion of the powders to the intensity of the interparticle interaction.

Granulação a seco de uma massa cerâmica para grês porcelanato

São apresentados os resultados de um estudo sobre a granulação a seco de uma massa cerâmica para grês porcelanato. A preparação da massa é uma das etapas mais importante na ciência de processamento cerâmico. A massa cerâmica foi formulada usando caulim, albita e quartzo em proporções pré-determinadas. As matérias-primas foram moídas a seco e em seguida microgranulada utilizando um granulador intensivo contra corrente Eirich. Foram determinadas as seguintes características da massa cerâmica granulada: composição química, distribuição de tamanho de grânulos, morfologia, massa específica aparente, massa específica vibrada, plasticidade, índice de Hausner e o comportamento de compactação. Com base nos resultados pode-se concluir que o processo via seca foi efetivo na granulação da massa cerâmica para grês porcelanato.