National Repository of Grey Literature 2 records found  Search took 0.00 seconds. 
Processing optimalization of biodegradable starch based packaging and its characterization for adaptation on production technology
Krahulová, Veronika ; Ondreáš, František (referee) ; Lepcio, Petr (advisor)
This diploma thesis focuses on the problematics of preparation of biodegradable starch based packaging. The aim of the thesis is to optimize the preparation and verify the characteristics for further adaptation and production technologies. The films consisted of starch, PVA and glycerol. Four types of starches, three types of PVA and different ratios of glycerol were tested. Films were prepared by casting with glycerol as a plasticizer, instead of distilled water, to reduce the energy cost of the preparation. The mechanical properties of the films were tested as well. The experimentally determined values of elongation at break and tensile strength of the wheat starch films were compared with a semiempirical model. Results revealed that the preparation of thermoplasticization of starch with glycerol leads to a considerable increase in elongation at break but at the same time to a marked decrease in tensile strength compared to the preparation from solution. The rheological properties of the prepared films were also investigated. Infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to study the structure of the films.
Possibilities of enhancement of kaolin whiteness
Krahulová, Veronika ; Bartoníčková, Eva (referee) ; Opravil, Tomáš (advisor)
This thesis focuses on problematics of increasing the kaolin whiteness index. The aim of the thesis is to verify possibilities and efficiency of the mechanical method of increasing whiteness of kaolin using sand of a defined fraction. This method cannot be considered as a whitening operation of kaolin but as a pre-treatment of the raw material or as one of the steps in increasing the whiteness. There have been tested diverse proportions of added sand with which the batch of kaolin material was intensively mixed for various times. Moreover, there has been tested influence of water and total batch volume. To characterize prepared samples there have been used several methods; XRF and XRD analysis was used to determine the elemental and phase composition of raw kaolin before and after mechanical sand action. The UV - VIS method with reflectance was used to assess the achieved whiteness.

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