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Breaking of Rod-shaped Model Material during Compression.
Kulaviak, Lukáš ; Pěnkavová, Věra ; Růžička, Marek ; Punčochář, Miroslav ; Zámostný, P. ; Grof, Z. ; Štěpánek, F. ; Schöngut, M. ; Havlica, Jaromír
The breakage of a model anisometric dry granular material caused by uniaxial compression was studied. The bed of uniform rod-like pasta particles (8 mm long, aspect ratio 1:8) was compressed (Gamlen Tablet Press) and their size distribution was measured after each run (Dynamic Image Analysing). The compression dynamics was recorded and the effect of several parameters was tested (rate of compression, volume of granular bed, pressure magnitude and mode of application). Besides the experiments, numerical modelling of the compressed breakable material was performed as well, employing the DEM approach (Discrete Element Method). The comparison between the data and the model looks promising.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22018011012170 - PDF
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Powder Rheology of Nanocrystalic Particles.
Kulaviak, Lukáš ; Pěnkavová, Věra ; Růžička, Marek ; Punčochář, Miroslav ; Zámostný, P. ; Grof, Z. ; Štěpánek, F. ; Schöngut, M. ; Havlica, Jaromír
Pigments are mostly nanometric powder of anisometric particles providing complex rheological behaviour. The interparticle forces of grains (> 100 μm) are based on direct contact, which is mainly influenced by the particle size and shape. On the other hand powder (< 4 μm) and especialy nanometric powder (< 100 nm) is influenced mainly by electrostatic charges and by moisture (respectively by the liquid and solid bridges forming). However the morphology affects the surface area and thus the distribution of surface charge and\nthe moisture content on/in single particle. Last but not least, it is also good to know the history of the powder, i.e. the effect of aging and the memory of the powder on the strength of the material. The nanometric powder TiO2 was chosen as a demonstration material and measuring device was FT4 powder rheometer.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22018011012520 - PDF
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Optimizing Flow and Segregaton Properties of Lactose/Microcrystalline Cellulose Mixture for Tablet Compression.
Zámostný, P. ; Kreibichová, B. ; Hofmanová, D. ; Kulaviak, Lukáš ; Zelenková, K. ; Růžička, Marek
The present study deals with optimizing the flow and segregation properties of levocetirizine hydrochloride formulation, where the delay between homogenization and tablet compression was found to affect the tablet content uniformity. In addition to API, the base formulation comprised spray dried lactose monohydrate, milled lactose monohydrate 200 mesh, Avicel PH 101 microcrystalline cellulose, and minor excipients. Several alternative mixtures were prepared using the same total composition, but different grades of lactose and microcrystalline cellulose. These mixtures were then tested for the segregation behavior in an in-house segregation device and the flow properties using the Freeman FT4 powder rheometer. The segregation tests showed the grade of lactose is essential for mixture in-flow segregation. While SD lactose mixtures increased the API content in a direction countercurrent to flow, the milled lactose mixtures segregated API concurrently. Mixtures using both lactose grades showed combined effect, resulting in the least segregation due to the two segregation processes competing with each other. However, the segregation was extremely sensitive to ageing of the mixture. It was also found that each type of lactose causes a different flow regime of the mixture in process vessels. In order to improve the content uniformity of the tablets, it was found the volumetric flow regime of transport to tablet press is required as well as the aggregate formation should be prevented.\n
Fulltext: content.csg - PDF
Plný tet: PROCEEDINGS OF THE 3RD INTERNATIONAL CONFERENCE ON CHEMICAL TECHNOLOGY - PDF
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