Our research considers the leuco dye-developer-solvent composites which show thermochromic change of absorption of visible light. The temperature of the colour change depends by large extent on the used solvent, but the molar ratio of other compounds used is also important. Moreover, the preparation procedure may influence the thermochromic effect to some extent, but this phenomenon was not studied enough in detail yet. The aim of the present work is to compare the properties of the composites, slowly cooled in icy water and the one quenched in liquid nitrogen.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 5758234Basic properties of thermochromic materials were explained considering the three origins (absorption, reflection and scattering). The leucodye –based and liquid-crystalline materials were shown in more details. The abilities of these materials to be used in printing were regarded. The research of these materials going on at National Institute of Chemistry was reviewed. Much attention was devoted to current applications of thermochromic printing inks for packaging, which are currently rare, and the ability of different thermochromic materials for new applications in smart packaging, especially for irreversible temperature indicators. Lecture was goven on international forum of researchers working on the aea of smart packaging.
F.30 Professional assessment of the situation
COBISS.SI-ID: 5771546The thesis is dedicated to analysis of passive electronic elements which were prepared by screen printing. Commercially available printing inks were applied, including three types of silver-based conductive inks and one dielectric ink. The feasibility of four papers intended for conventional printing was analysed and compared with the results obtained for the samples prepared on the paper dedicated for printed electronics. The print forms were prepared for single- and three-layered elements. For preparation of samples screen printing technology was applied on the five selected substrate materials. Special attention was devoted to the properties of printing inks as a result of printing and drying processes and their influence on the electrical properties of final samples, especially the multi-layered ones. The electrical, thermal and chemical properties of the printed passive electronic components were analysed in details. The profiles and shapes of lines used in single-layered elements were evaluated together with the adhesion of the functional ink on the applied papers. The electrical resistivity of the conductive inks was studied as a function of screen density, type of paper substrate and drying conditions. The results confirm that the electrical conductivity depends on the examined printing parameters. The resistivity increases with the screen density and diminishes with drying temperature. The influence of surface roughness of the used paper substrates on electrical resistivity of prints was also evaluated. The preparation of the prints was optimized by proper selection of mesh density and drying conditions. The print quality of three-layered elements prepared as parallel-plate capacitors was also evaluated. Their electrical properties were thoroughly analysed with special attention on the material properties of the dielectric layer. The electrical functionality of capacitors was studied in terms of the state of polymerization of UV-curable dielectric layer, varied by the energy applied for curing. The boundary between the dielectric and conductor layers was analysed in dependence on the curing energy applied for dielectric layer in conditions of single- and double printed dielectric layer. It was shown that parallel-plate capacitors are feasible using single-printed dielectric layer only if the dielectric is completely polymerized. This way the thinnest possible dielectric is assured, thus the largest capacitance of the capacitor.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 279444992