Magnetic properties of polymer matrix composites filled with ferrite powders

Purpose: The aim of this paper was to present magnetic properties research results of polymer matrix composites. The influence of the kind of fillers and amount of fillers on the magnetic properties of the composites was studied and is presented in this paper. Design/methodology/approach: Epoxy resin filled with three different amounts (15%, 25% and 35%vol.) of filler and three kinds of ferrite powders were prepared by gravitational casting in order to obtain gradient polymer matrix composites. Magnetic properties of polymeric composites were measured by SQUID magnetometer (MPMS XL7 Quantum Design). All measurements were carried out in the temperature 300 K and magnetic field up to 7 T. Findings: The research findings showed that addition of ferrite powders to epoxy resin caused increased values of magnetic remanence. Moreover it was observed that the higher values of remanence were for polymer composites with anisotropic filler than that with isotropic. Research limitations/implications: Presented studies have been limited to the content of 35%vol. of filler because of difficulties with casting of higher filled composites. Higher value of filler content caused dramatic increase of viscosity. Practical implications: Magnetic composites with different content of magnetic filler are still investigated by scientists in order to improve magnetic properties of composite materials, which are used in various industries. Originality/value: Presented results of magnetic properties dependence on content and type of filler of new gradient polymer matrix composites are novel and original

Shear-Induced Molecular Orientation of Compression Moulded PE-HD Sheets

The article presents experimental results on orientation of polymer macromolecules in compression moulded high density polyethylene sheets. Properties anisotropy of thermoplastic films or sheets, that are usually formed in the extrusion process, causes deformation of thermoformed products and is a serious technological problem. One of the possible solutions of this problem is application of compression moulded sheets. The paper presents the results of tests of selected strength characteristics of compression moulded PE-HD sheets. A static tensile test was performed and Charpy impact strength was determined. Additionally Chrystler’s orientation test was executed. For comparison the same experiments were performed on extruded sheets. Samples were cut in directions perpendicular and parallel to the direction of polymer flow in pressing and extrusion processes. The obtained results indicate that the compression moulding technique allows the production of sheets that do not exhibit statistically significant anisotropy of the tested strength properties

Prediction of Strength Properties of Filling Packets in Selected Cooling Towers

The operating conditions of thermoplastic polymer materials determine the changes in their functional properties. Accelerated aging tests do not give a full picture of the changes taking place in the polymer material, hence the conclusions drawn on the basis of exposure of these materials to damaging effects in real operating conditions are particularly important. The aim of the study was to determine the degree of degradation of polypropylene films used in the drainage blocks of cooling towers in a selected power plant in the Silesian voivodship, which allowed forecasting the operating time over a period of 10 years. A number of 600 mm high drip blocks were tested, on which 300 mm high blocks were mounted. The tests were carried out on films subjected to the aging process in the conditions of continuous operation of a cooling tower (almost 100% humidity). The water flow is accompanied by heat exchange, the side effect of which is deposits formation on the surface of the drip blocks, negatively affecting the operation of the cooling tower. The degree of degradation resulting from operational aging was assessed on the basis of the strength properties determined in the static tensile test, thermogravimetric analysis and FTIR spectra. Changes in properties during operation were determined on the basis of the obtained results of the strength tests, which were compared with the tensile strength and elongation at break of reference samples (not subjected to aging in the operating conditions of cooling tower drip blocks). The obtained results were related to the properties of the reference samples not subjected to the degradation process. Based on the collected data, the tensile strength and deformation at fracture after a 10-year service life were predicted