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Open access

I. Polowczyk, Z. Sadowski and D. Smoczyńska

Biomodification of plastic surfaces and depression process

Plastics from the municipal waste must be recycled on a large scale. This contribution describes the initial work to determine the surface energy of plastic waste. Results of such investigations were correlated with both sedimentation and flotation data. The penetration rate of a liquid into the horizontal powder layer was measured; basing on the rate of liquid penetration, the effective radius of the porous bed was calculated. For modification of the surface of plastics, tannic acid, sodium lignin sulfonate and microbial broth from Pseudomonas aeruginosa growth were used. In order to determine the effect of these reagents on the surface energy of plastic powders, the penetration and flotation experiments were carried out. For polystyrene and polyethylene the estimated surface energy was 28.6 [mJ/m2] and 24.5 [mJ/m2], respectively. These results were correlated with the sediment height extreme of plastic powders in solvent pairs. The adsorption of tannic acid, sodium lignin sulfonate and biosurfactants from microbial filtrate caused an increase of the surface energy of plastic particles. For instance, the free energy of polyethylene particles was 34.9 [mJ/m2] after the sodium lignin sulfonate treatment, and 35.57 [mJ/m2] for the tannic acid adsorption. The natural flotation of plastic particles in the presence of modifying reagents was shown to be dependent on the concentration of these reagents.

Open access

J. Bojarski, R. Smolenski, P. Lezynski and Z. Sadowski


The assurance of the electromagnetic compatibility of sensitive smart metering systems and power electronic converters, which introduce high-level electromagnetic interference is important factor conditioning reliable operation of up to date power systems. Presented experimental results have shown that currently binding, frequency domain tests are ineffective for the evaluation of data transmission error hazards. The proposed in this paper mathematical, time-domain model, based on Diophantine equation, enables evaluation of data transmission errors caused by interference introduced by DC-DC power electronic interfaces with deterministic modulation. In the paper there have been presented possible application areas for the proposed model.

Open access

Z. Gronostajski, M. Hawryluk, J. Jakubik, M. Kaszuba, G. Misiun and P. Sadowski

The paper presents selected examples of solutions and specific user applications associated with the industrial forging processes. Various process specific issues encountered during many years of bilateral collaboration with the forging industry are addressed and analysis methods are presented. As demonstrated in numerous articles and publications, the parameters influencing the die forging process are subject to complicated and mutually related dependencies, which can affect and complicate the methods of analysis. For this reason, researchers, more and more frequently, involve the use of additional support tools such as CAD / CAM / CAE, numerical modelling based on FEM, tool surface scanning methods, physical modelling, advanced microstructural research and dedicated control-measurement systems to validate engaged solutions. The research conducted by the authors included mainly: an analysis of the preform preparation, the impact of the geometry on the forging quality and the heating methods of the material and the tools, analysis of the tribological conditions, as well as an optimization of selected processes in respect of the force parameters, strain and temperature distributions and finally, a weight minimization of the input material. The issues discussed by the authors in the article intend, on the basis of the experience of its creators, to review the issues of the current forging technology and to indicate its possible solutions and development directions.