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  • Author: Marek Jałbrzykowski x
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Abstract

This paper presents the problem of thermal degradation of thermoplastic materials processed using the injection method. Attention was paid to the issue of the optimal selection of a dye for modifying the base materials. For the selected materials and dyes, derivatograph tests were performed in order to assess their thermal characteristics and breakdown kinetics. Additionally, tribological tests and microscope observations of selected samples were performed. The obtained test results suggest a diverse level of thermal processes in the analyzed materials. This is crucial for the appropriate selection of dyes for plastic materials. As it turned out, the tribological properties of materials can also influence the technological quality of the injected alloy.

Abstract

The paper presents results of microbiological research of plastic elements. Plastic elements were made of the polystyrene composition with addition of nanosilver and nanocopper with a laboratory extruder EHP 25ELine. Microbiological research was carried with regard to evaluation of antifungal impact of nanoadditives according to international standards with Cryobank (Mast Diagnostica). A positive impact of nanoadditives on antifungal properties of polystyrene elements produced by means of extrusion which is very favourable in the aspect of their use in agri-food processing.

Abstract

The paper presents example tests of the functional quality of selected designs of dental bridges. These were: porcelain bridges on a metal base (cobalt based alloy), porcelain bridges on a zirconia base (zirconia ceramic – Zirkon Zahn), and full zirconia bridges (Zirkon Zahn). For the purpose of the study, durability of bridges in cyclic fatigue testing was adopted as a measure of their quality. The tests were carried out on a Zwick Roell Z010 universal testing machine. They consisted in cyclic loading and unloading of dental bridges mounted on gypsum models at a loading force of F= 400 [N] and a frequency of load of f= 1 [Hz]. Each bridge was subjected to a cycle of 7200 loads. The results show that there are no significant differences in the functional quality of the bridges.

Abstract

We report the results of studies for the radiation-stimulated changes in electro-physical characteristics of surface-barrier Al–Si–Bi structures based on p-Si. We demonstrate that the X-ray irradiation is accompanied by different processes which depend on the density of the dislocations in the original silicon crystals. A usual evolution of the existing structural defects and their radiation-stimulated ordering dominate when the concentration remains low enough. Increase in the concentration causes the increasing role of generation of additional radiation defects. Modelling of the underlying physical processes has testified that the near-contact Si layers are strained. They act as getters for the structural defects and impurities.