This diploma thesis follows the degradation of inkjet print by ultraviolet radiation and ozone effect for different types of papers. Colour test charts for the evaluation of accelerated ageing effect of ultraviolet light and gas fading were designed. These test charts were printed by dye-based inks on selected receiving media and exposed to ozone-enriched environment, UV radiation and their combination. The colorimetric values L* a* b* were calculated from spectral data of all patches of the test charts. The ozone effect on the prints was evaluated in the terms of total colour difference and dye concentration. The degradation of dye caused by ozone was observed also in a long-term period, after the contact of sample with ozone was terminated. Results of printed samples accelerated ageing by UV radiation and those that were influenced by the ozone effect were evaluated in the same way. It was found out that UV radiation and ozone treatment have a different effect on the degradation of dyes. The degradation rate is also strongly influenced by the receiving layer composition of papers used for inkjet printing. Also the catalytic effect of dyes was evaluated.

Le travail entre dans le cadre de la nouvelle tendance à la recherche d’une électronique mécaniquement flexible basée sur des transistors en couche mince constitués uniquement de matériaux organiques (OTFT). OTFT de type n et de type p ont été fabriqués par la technique de dépôt par impression (inkjet) et étudiés. Les paramètres d’impression (jetabilité, mouillabilité, imprimabilité et possibilité d’obtention de différentes formes), de chaque encre permettant le dépôt de couches conductrices, isolantes et semiconductrices, ont été systématiquement étudiés. Les OTFT de type n basés sur du C60 se sont montrés non fiables, principalement du fait de la faible solubilité du C60 dans les solvants organiques. Les OTFT de type basés sur du Tips-pentacene ont montré par contre une grande fiabilité. Le travail global constitue une large revue des problèmes et difficultés rencontrés dans la fabrication de transistors fabriqués entièrement par impression jet d’encre. Des solutions ont été trouvées et de nouvelles idées sont proposées. / Present work deals with the new trend to get highly flexible electronics by using fully Organic Thin-Film Transistor (OTFT) as the basic element of this electronics. Fully organic n-type as well as p-type OTFT processed by inkjet printing are studied. Printing parameters of each ink, jettability, wetting, printability, and patterns optimization, leading to the deposition of conductive contacts, gate insulator and semiconducting active layer are studied. Process of n-type OTFT based on C60 is shown as unreliable, mainly due to the poor solubility of C60 in organic solvent. In the contrary, p-type OTFTs based on Tips-pentacene are much more reliable. The work is a large overview of the issues and the difficulties that have been to jump and to solve in the way to fabricate fully printed organic transistors. Some solutions have been given and new ideas have been proposed.

Hydrogen production via the electrolysis of water has gained a lot of attention in the last couple of years. Research related to electrolysers is mostly aimed towards decreasing the noble–metal catalyst content. In this study the presently used catalyst application techniques were reviewed and critically examined to find commercially applicable and effective methods. Selected methods were then practically applied to determine their feasibility and to gain “know–how” related to the practical application of these techniques. The selected techniques were the hand paint, inkjet print, screen print and spray paint techniques. Meaningful comparisons were made between the methods in terms of parameters such as practicality, waste of catalyst and microstructure. The results point out that the hand paint and spray paint methods are feasible methods although there are improvements to be made. The hand paint method was improved by applying a carbon micro porous layer to the gas diffusion layer before the painting is carried out. The addition of the carbon layer reduced the soaking of the catalyst–containing ink through the gas diffusion layer. A method not initially investigated was identified an evaluated and showed promising results in lowering the mass of catalyst applied. This method comprised of sputtering a layer of catalyst material onto a prepared gas diffusion layer. It also came to light from the results that electrodes, and therefore membrane electrode assemblies, can be produced at a much lower cost than the commercial available membrane electrode assemblies. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2012.

Hydrogen production via the electrolysis of water has gained a lot of attention in the last couple of years. Research related to electrolysers is mostly aimed towards decreasing the noble–metal catalyst content. In this study the presently used catalyst application techniques were reviewed and critically examined to find commercially applicable and effective methods. Selected methods were then practically applied to determine their feasibility and to gain “know–how” related to the practical application of these techniques. The selected techniques were the hand paint, inkjet print, screen print and spray paint techniques. Meaningful comparisons were made between the methods in terms of parameters such as practicality, waste of catalyst and microstructure. The results point out that the hand paint and spray paint methods are feasible methods although there are improvements to be made. The hand paint method was improved by applying a carbon micro porous layer to the gas diffusion layer before the painting is carried out. The addition of the carbon layer reduced the soaking of the catalyst–containing ink through the gas diffusion layer. A method not initially investigated was identified an evaluated and showed promising results in lowering the mass of catalyst applied. This method comprised of sputtering a layer of catalyst material onto a prepared gas diffusion layer. It also came to light from the results that electrodes, and therefore membrane electrode assemblies, can be produced at a much lower cost than the commercial available membrane electrode assemblies. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2012.