National Repository of Grey Literature 111 records found  previous11 - 20nextend  jump to record: Search took 0.00 seconds. 
Determination of the kinetics of crushing industrially produced tablets
Čechalová, Kateřina ; Řehula, Milan (advisor) ; Musilová, Marie (referee)
7.2.Summary Determination of the Kinetics of Crushing of Mass-Produced Tablets The degree paper aimed to determine the optimal parameters of the devices for the evaluation of the strength of tablets. Rates of preloading from 0.01 to 0.1 mm/s, preloading from 1 to 4 N, and rates of the cycle from 5 to 20 N/s were tested. These parameters were evaluated on the basis of the records of the force-course. Deformation curves were employed to calculate the course of crushing in mm, crushing force in N, and energy of crushing in N.mm. The reading of the curves was evaluated as well. The obtained results were evaluated using the method of the analysis of diameters following Otto. The results show that for the standard determination of mechanic resistance of tablets, the following adjustment of the device is suitable: rate of the cycle, 0.01 N/s, preloading, 4 N, rate of preloading, 5.mm/s.
Determining the plasticity of microcrystalline celulose
Skálová, Marie ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee)
Important properte of pressed (compacting) materials is their energy and plasticity. For their calculation is used several methods. One of values elasticity or plasticity energy from record power-line, in another metod is used elastic recovery, which is used for calculation of Young's elastic modul and the third one value stress relaxation of tenseness. In this analyze we can get parameters as FminA, FminB, Fpl and also characterization of ralation dependence compression in the time. In this dissertation is valueted one of the most common excipient microcrystaline celulose by all these methods. Basic characteristic is Young's elastic modul ,which is 253,794MPa and total plasticity is 995,48. We can say, that values of total plasticity means good compressible material and that plasticity increases with increasing of total plasticity.
Determination of the Kinetics of the Crushing Process of Tablets Containing Paracetamol
Juhaňáková, Jana ; Řehula, Milan (advisor) ; Musilová, Marie (referee)
Juhaňáková Jana - diplomová práce - 2006 The diploma theses deal with the measurement of mechanical resistance of tablets on basis of force - displacement record. The new method compared to the classical method characterizes mechanical resistance by means of destruction and destructive energy. Theoretical part of the work describes characterization and distribution of granules and tablets, characterization of additives used for production of tablets. It deals with the starch group in detail as well. The aim the experimental work was the determination of optimal parameters for measurement of the kinetics of destruction of tablets, preloading, rate of preloading a cycle. Commercially produced tablets of Paralen 500 were evaluated. The optimal parameters for the measurement of mechanical resistance of tablets by means of T1 - FRO 50 by differential record method are the following: preloading 0.1 N, preloading rate 0.1 mm/s, cycle rate 1.0 mm/s
Determining the plasticity of mannitolum
Votava, Jakub ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee)
The visco-elastic characteristics and knowledge of them are the important factors that influence pressability of materials. These characteristics differ for every material and it is possible to determine them by variety of methods. In our thesis (chapter Experiments) we evaluated the relationship "force - travel" and determined elasticity and plasticity of materials. The test of relaxation of tense is another way to determine plasticity of materials. The results are parameters of FminA, FminB, FPL and parameters of single-parametric equation that describes decrease of preassure in a tablet during the relaxation period. These parameters and their evaluation are the goal of this thesis. We determined the Young's modulus of elasticity from the tablet dilatation measure restults. The value of Young's modulus of elasticity for mannitol is 413,36 MPa. The value of total plasticity Pc is 91,34177 MPa.s. Generally: increasing value of total plasticity determines increase of tablet material pressability.
Determination of Plasticity in Tablets from Microcrystalline Cellulose
Křivková, Blanka ; Řehula, Milan (advisor) ; Musilová, Marie (referee)
Determination of plasticity in tablets from microcrystalline celullose Blanka Křivková, 2007 Microcrystalline celullose is widely used as a filler for direct compression. Avicel PH 102 is very often used because of its size of particles (100 μm), appropriate, bulk volume, compressibility. The aim of Diploma thesis was to determine plasticity, to describe influence of the compression force on the plasticity and influence of the type of microcrystalline cellulose and compression conditions on plasticity. The plasticity was determined from graphs showing the decreasing trend of force on the time.Three methods using "one-point" evaluation put into rate value of maximal and minimal forces. The third method evaluate rate of area. These three methods gave comparable result. Two sections of curve from graphs showing the dependence of the plasticity on the compression force can be distinguished. The first one characterized the phase of precompression second one characterized the plastic deformacion of tablets. We can also confirmed the influence of different compression conditions on the second section of the curve. Type of microcrystalline celullose on this section was minimal.
Energy balance of crushing tablets
Čámský, Václav ; Řehula, Milan (advisor) ; Musilová, Marie (referee)
Čámský Václav - Rigorózní práce - 2006 This work deals with energy balance of tablet destruction. The characterization of individual groups of tablets and characterization of two fillers - lactose and microcrystalline cellulose- for direct compression is mentioned in the theoretical part. The aim of the work is to find out the influence of the type of a dry filler on the punch displacement and to describe the dependence between the parameter of the compression process E2 and parameter of the destructive process DE. The determination was carried out with the tablets of Avicel PH 102, Flowlac 100 and lactose anhydride using T1 - FRO 50 device. It follows from the results that destruction displacement of microcrystalline cellulose is substantially longer than in the case of lactoses. Microcrystalline cellulose compared to lactoses consumes significantly less amount of energy. The cycle rate 0.1 mm/s was used for measurement of mechanical resistance.
Calorimetric evaluation of compatibility between the components of the mixtures for tableting
Kopecká, Milada ; Řehula, Milan (advisor) ; Musilová, Marie (referee)
Kopecká Milada - Rigorózní práce - 2006 This work deals with the compatibility of a medical substance with 15 additives using the DSC method. Theoretical part of the work describes thermoanalytical methods, methods of thermal analysis, calorimetric methods and differential scanning calorimetry. Besides the work deals with the crystalline structure of solid compounds. The aim of experimental part of the work was the calorimetric evaluation of the medical substance itself, all additives and mixtures of medical substance with additives. The compatibility was measured by means of DSC 200 PC Netzsch. The result of the work was to prove the compatibility of the medical substance with lactose, Kopovidone, Povidone 25, silica, mannitol, Emcompress, magnesium stearate, and calcium stearate. Incompatibility was found out between the medical substance and glycerol behenate.
Determination of Residual Plasticity in Tablets from Microcrystalline Cellulose
Filipčíková, Michaela ; Řehula, Milan (advisor) ; Musilová, Marie (referee)
Determination of Residual Plasticity in Tablets from Microcrystalline Cellulose Michaela Filipčíková, 2007 Abstract Microcrystalline cellulose is an important pharmaceutical excipient. Ceolus KG 802 is one type of microcrystalline cellulose. The aim of this Diploma thesis was the determination of plasticity in tablets from microcrystalline cellulose (Ceolus KG 802) and to valuate the influence of compression force on plasticity. The influence of both a type of microcrystalline cellulose and different compression conditions on the second section of the graph curve showing the relation of the plasticity to the compression force was investigated as well. Test Xpert V9.01, Microsoft Excel and Origin Professional 7.5 were used for processing compaction data. The plasticity was determined from graphs showing the decreasing trend of force on the time. We used methods which were based on identification of maximum and minimum forces and then method which was based on valuation of the area. Considering to uncertainty in the scope of plasticity is the plasticity considered as a residual one. We found that these three methods gave comparable results. We were able to distinguish two sections of the curve from graphs showing the relation of the plasticity to the compression force. The first section characterizes the...
Determining the compression behaviour of fillers and magnesium stearate
Szwedová, Lenka ; Řehula, Milan (advisor) ; Špaček, Vladimír (referee)
1 Abstract The energy of tablets compaction is obtained from the force-distance record. The aim of this work was to determine accumulated energy in a tablets (plastic energy), to determine energy released from a tablet after compaction (elastic energy) and summation of these two energies. Mixtures of magnesium stearate 0%, 0,5% and 1% were prepared in a blending cube. The T1 - FRO 50 compacting machine was used for compacting tablets (weight of each tablets was 500 mg). Compacting forces were 5, 10 and 15 kN. In the first procedure the compaction was ceased after reaching the maximal compaction force, in the second procedure the upper punch was stopped when the maximal compaction force was reached and during 180 s dwell time of decreasing compacting force was recorded while the tablet height was kept constant. The results show that increasing concentration of lubricant leads to a decrease of accumalated energy in a tablet and on the contrary it leads to an increase of energy released from a tablet. The 180 s dwell time with a tablet height kept constant increases plastic energy because of forming more bonds. Microcrystalline cellulose is characterized by higher plastic and lower elastic energy than lactose monohydrate.
Compressibility of powder mixture with antifrictional agents.
Motlová, Tereza ; Řehula, Milan (advisor) ; Ďoubal, Stanislav (referee)
The tablet is formed by the effect of compression force during compression process. The supplied energy is consumed in the formation bonds between particles and molecules of compressed material. For that reason it is important to determine the size of energy to be applied for forming tablets. The most common method for detecting the size of the energy is rating of force- displacement profile. In this work were monitored two factors affecting energy compressing. It was a compression pressures of size 5, 10 and 15 kN and research of the influence of frictional materials on the energy compressing. These effects were observed for tablets compressed from microcrystalline cellulose Avicel PH 102. As the frictional material was used magnesium stearate, Aerosil 200, Syloid AL - 1 and Syloid 244. As the parameters of energy were evaluated the following parameters: pre-compression energy E1, plastic energy E2, elastic energy E3, energy used for the compression Elis, total energy Emax and plasticity. The results of this work indicates that compression pressure increases the studied energy except plasticity, where is reduced of this parameter. The presence of friction substances reduces parameter E1, E2, Elis, Emax and plasticity and on the contrary increases the parameter E3.

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