3 resultados para KRAFT

em AMS Tesi di Dottorato - Alm@DL - Università di Bologna


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The thesis focuses on Karl Kraus’s rewritings of some Shakespeare plays and copes with the concepts of “translation” and “quotation” as commensurable forms of intertextuality. Building his Shakespeare’s Bearbeitungen as a montage of quotations of previous German translations, Karl Kraus creates a new kind of hybrid intertextuality that goes beyond the boundaries between quotation and translation. In my opinion, Karl Kraus understands quotation and translation as spatial concepts: in his rewritings he puts Shakespeare’s text into his geometrical and critical “perspective”. The thesis focuses also on the evolution of quotation and translation in Karl Kraus’s work: even maintaining their satirical and destruens function, they develop an “affirmative” role and are used in order to redefine the literary canon. The thesis investigates this form of intertextuality from a comparative point of view, referring to the translation studies (Hermans, Bassnett, Lefevere, Apel, Berman, Meschonnic), theories of intertextuality (Genette, Barthes, Worton, Orr), studies on quotation and montage (Compagnon; Möbius, Hage), and studies on Karl Kraus (Kraft, Ribeiro, Scheichl, Fischer, Timms, Canetti and the famous essay of Walter Benjamin). It also contains a survey of Theater der Dichtung’s historical framework and several comparisons between Karl Kraus’s and other early 20th translations of Shakespeare’s plays.

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After the development of power electronics converters, the number of transformers subjected to non-sinusoidal stresses (including DC) has increased in applications such as HVDC links and traction (electric train power cars). The effects of non-sinusoidal voltages on transformer insulation have been investigated by many researchers, but still now, there are some issues that must be understood. Some of those issues are tackled in this Thesis, studying PD phenomena behavior in Kraft paper, pressboard and mineral oil at different voltage conditions like AC, DC, AC+DC, notched AC and square waveforms. From the point of view of converter transformers, it was found that the combined effect of AC and DC voltages produces higher stresses in the pressboard that those that are present under pure DC voltages. The electrical conductivity of the dielectric systems in DC and AC+DC conditions has demonstrated to be a critical parameter, so, its measurement and analysis was also taken into account during all the experiments. Regarding notched voltages, the RMS reduction caused by notches (depending on firing and overlap angles) seems to increase the PDIV. However, the experimental results show that once PD activity has incepted, the notches increase PD repetition rate and magnitude, producing a higher degradation rate of paper. On the other hand, the reduction of mineral oil stocks, their relatively low flash point as well as environmental issues, are factors that are pushing towards the use of esters as transformer insulating fluids. This PhD Thesis also covers the study of two different esters with the scope to validate their use in traction transformers. Mineral oil was used as benchmark. The complete set of dielectric tests performed in the three fluids, show that esters behave better than mineral oil in practically all the investigated conditions, so, their application in traction transformers is possible and encouraged.

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This work mainly arises from the necessity to support the rapid introduction of different biobased polymers that the industrial sector has been facing lately. Indeed, while considerable efforts are being made to find environmentally and economically sustainable materials, less attention is paid to their need to be properly compounded to fulfil increasingly rigorous technical and quality requirements. Therefore, there is a strong demand for the development of a novel generation of compatible additives able to improve the properties of biobased polymers while respecting sustainability. With this in mind, a new class of biobased plasticizers is herein proposed. Five different ketal-diesters were selectively synthesized starting from levulinic acid, a promising renewable chemical platform. These molecules were added to poly(vinyl chloride) as model polymer to test their plasticizing effectiveness. Complete morphological, thermal and viscoelastic characterizations showed a clear correlation between the structural features of the ketal-esters and the properties of the material. In addition, no significant leaching was found in both hydrophilic and lipophilic environments. Importantly, the proposed ketal-diesters performed comparably and, in some cases, even better than commercial plasticizers. The same molecules were then added to bacterial poly(3-hydroxybutyrate), a semicrystalline polyester characterized by poor thermal and mechanical properties. Morphology assessments showed no phase separation and the plasticizing effectiveness was confirmed by thermal and viscoelastic analyses, while leaching tests showed low extraction values. Readily usable fractions with controlled structure and tailored properties were obtained from highly heterogeneous industrial grade Kraft lignin. These fractions were then added to poly(vinyl alcohol). Promising preliminary results in terms of compatibility were achieved, with thermograms showing only one glass transition temperature. Finally, a fully biobased glycerol-trilevulinate was successfully synthesized by means of a mild and solvent-free route. Its plasticizing effectiveness was evaluated on poly(vinyl chloride), showing a significant decrease of the glass transition temperature of the material.