Polyoxymethylene (POM) is one of the most popular thermoplastic polymers used in the industry. Therefore, the interest in its potential applications in rapid prototyping is understandable. Nevertheless, its low dimensional stability causes the warping of 3D prints, limiting its applications. This research aimed to evaluate the effects of POM modification with ethylene-vinyl acetate (EVA) (2.5, 5.0, and 7.5 wt.%) on its processing (by melt flow index), structure (by X-ray microcomputed tomography), and properties (by static tensile tests, surface resistance, contact angle measurements, differential scanning calorimetry, and thermogravimetric analysis), as well as very rarely analyzed emissions of volatile organic compounds (VOCs) (by headspace analysis). Performed modifications decreased stiffness and strength of the material, simultaneously enhancing its ductility, which simultaneously increased the toughness even by more than 50% for 7.5 wt.% EVA loading. Such an effect was related to an improved linear flow rate resulting in a lack of defects inside the samples. The decrease of the melting temperature and the slight increase of thermal stability after the addition of EVA broadened the processing window for 3D printing. The 3D printing trials on two different printers showed that the addition of EVA copolymer increased the possibility of a successful print without defects, giving space for further development.

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Electrostatic hazards are considered a category of technical hazards occurring in hard coal mining. These hazards are related to the generation of excess electric charges forming as a result of most technological processes. Products manufactured from plastics that are classified as non-antistatic materials pose the greatest hazard. The article discusses the Polish and European legal regulations concerning the requirements for materials regarding their antistatic properties. It also presents the results of studies conducted at GIG concerning the systematization of the antistatic processing of plastics. Furthermore, the article proves that the procedure of applying antistatic properties to plastics is neither easy nor homogeneous. The introduced antistatic processing systematics (i.e., the identification of various antistatic processing realization methods) is meant to make both the manufacturers and customers aware of the various (often undesired) properties of modified plastics.

The article describes an attempt to assess the electrostatic properties of mechanical friction-induced sparking. Such sparks are the cause of numerous accidents in hard coal mines. The article summarizes accidents in hard coal mining in Poland in recent years. In most cases, the initials were mechanical sparks. Mechanical sparks contain energy, a part of which is related to their excess electrostatic charge, whereas the other part is of a different origin (kinetic or thermal energy, for example). The article tries to estimate how much of this energy is energy impact generated by electrostatics impact. It is hard to measure the dynamic electrostatic parameters like electric charge. Authors select four measuring methods. This test methods are prepared based on authors knowledge of electrostatic parameters and European standards dedicated to measure the electrostatics parameters. These circuits were prepared for four different spark parameters. Measurement methods of electrostatic field of sparks stream are not able to measure field potential of sparks. The measuring instruments do not have such a fast response time, adequate to the speed of the sparks. Spark generation and parameter measurement experiments were performed. The only method to determine the amount of electrostatic charge on sparks is to measure the entire charge by collecting sparks at the measuring electrode. The measuring system requires that the entire stream of sparks falls on the electrode. Tested transferred electrostatic charge of stream of sparks is about 10 nC. It means that this charge can be an effective ignition source for some explosive atmospheres. Electrostatic charge with Certain methods were rejected as inadequate following result analysis. A claim for one of the methods was submitted to the Patent Office of the Republic of Poland.

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