Browsing by Subject "murtolujuus"

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  • Kosimov, Yorkin (Helsingfors universitet, 2016)
    The main goal of this thesis was to examine the effect of the compaction speed on the compressional behaviour of two excipients, microcrystalline cellulose and starch, using an eccentric and rotary presses. First, the average weights of the tablets have changed due to the increasing speed, as the volume of die kept constant. They were grown, for eccentric press, or were reduced, for rotary press. Second, Compression force, needed to obtain tablets with similar strength, was increased during both tableting methods. The eccentric compaction was more stable regarding to the speed increase. Tablets were formed from all of the blends, with more or less success. Additionally, as a result of force increase, resulted tablets were denser and less porous because of speed expansions during eccentric press. However, the blends containing 80% or more starch were not able to form tablets during the rotary press, because of the very poor die filling. Furthermore, blend containing 60% starch has shown very poor tabletability at speeds over 34 rounds per minute. The elastic recovery of tablets was very sensitive to the speed rises and to the concentrations of excipients during the eccentric press. Tablets have demonstrated an increase in their elastic recovery values in all cases. However, the tablets with a higher concentrations of starch were significantly more sensitive to the increasing compaction velocity. According to these results, it can be concluded that the starch exhibit more elasticity than microcrystalline cellulose. The effect of magnesium stearate on tablets' properties, such as the weight and the porosity, and compaction parameters, such as ejection force have also examined. As it expected from boundary lubricants, magnesium stearate has significantly reduced the ejection force values, required for removing the tablet from the die, compared with unlubricated tablets. Additionally, tablets with lubricants were heavier and more porous. The compression force was adjusted according to the crushing strength values in rotary press. This was due to the fracture variations of such tablets during diametrical compression, which would give unreliable values of tensile strength. Moreover, elastic recovery, porosity, density values were not calculated for scored tablet, due to either the lack of punch displacement data from rotational machine or the relative complexity of measuring the volume of such tablets. If these values had been available for both machines, their comparison with respect to these parameters would be possible and the results of this thesis would have been more appropriate.
  • Palomäki, Emmi (Helsingfors universitet, 2012)
    3D-imaging is based on combining two or more pictures to form one three-dimensional picture. Most of the methods used provide only surface pictures, but tomography acquires also information about the inside-structure of investigated material. Young's modulus is a method, which has been used for long time to determine toughness hard materials, such as steal. In traditional method a beam-shaped piece is bent. When the size of piece, used force and amount of bending are known, Young's modulus of piece can be calculated. Although the method has traditionally been used to research very hard materials, it has been applied without changes with pharmaceutical materials. It is, however, open to the question whether or not the method is appropriate for those materials. There are also methods to determine Young's modulus based on compressing a tablet or using ultrasound. Determining tablet's toughness with ultimate strength test is complicated because it breaks tablet. For that reason it would be good to find compensatory methods to measure strength of tablet. The aim of the study was to validate Flash Sizer 3D appliance, which is used in 3D-imiging. Another goal was to investigate possible correlations between 3D-imiging, Young's modulus and traditional ultimate strength method. Lastly, the feasibility of Young's modulus as a substitute for traditional ultimate strength measurement in self life studies was investigated. Flash Sizer 3D was validated by measuring particle size distribution of pellets, which were made of microcrystalline cellulose (Cellets). Sizes of the investigated pellets were 100 µm, 200 µm and 500 µm. Also binary mixture of 100 µm and 200 µm was investigated. From microcrystalline cellulose was made tablets and 3D-pictures were taken. Ultimate strength test was made for half of the tablets. Young's modulus was measured from half of the tablets in tableting day, day after that and nine days after tableting. Results show that Flash Sizer 3D is suitable for investigating bigger Cellet. With smaller particles distinguishing of tablets wasn't probably good enough. Still it seems to be quite good method to determine surface roughness of tablet. Young's modulus seems to be very promising as compensating method for traditional ultimate strength measurement. In future in self life studies tablets hardness might be able to investigate by measuring Young's modulus and not measuring ultimate strength. If correlation between Young's modulus and solubility meets the case, Young's modulus might also replace also solubility measurements in self life studies.