The goal set for this paper was to investigate the relationship between gradation of filler particles content in the epoxy matrix and the gradation of electric properties. In order to characterize the electric properties, the surface resistivity was selected, because it determined the surface ability to electrostatic charging, important in expected applications. In particular, the influence of conditions of centrifugal casting technique and microstructure parameters on electric resistivity was searched. Experimental models were elaborated that juxtapose the dependence of surface resistivity on the volumetric content of the filler, as well as casting rotational velocity. Investigations results confirmed that achieved graded composites were characterized by the reduced ability of electrostatic charging on one side and good insulating properties on the other side. Measured surface resistivities of order 10⁹–10¹¹ Ω allow to classify them as surfaces with reduced susceptibility to static electricity accumulation. These composites may be applied in areas where antistatic properties of the surface, with preservation of insulating properties in the remaining volume of the composite, are beneficial.

The aim of the work was to achieve assumed gradation of hard coal particles distribution in epoxy matrix and thus gradation of properties. It was done by proper selection of compounds composition and conditions of the gradation formation. The graded composites were produced using centrifugal casting. Two types of epoxy resins as a matrix and two types of hard coal of various granulation as a filler were used. Samples in the form of bushings with radial carbon filler gradation were produced by changing filler type, its volumetric content and parameters of centrifugal casting. The first part of the paper presents results of graded materials structure investigations. The microscopic observations of the structure of composites prepared according to elaborated experimental program show that the composites are characterized by continuous change of the filler particles content in radial direction, so they can be classified as graded materials. Results also show that gradation of particles content and thus gradation of properties may be planned and foreseen when mechanisms of gradation formation are known.

This article presents the technology of making an adhesive joint using two primers: Corrosion Inhibiting Primer BR127 (previously used, containing chromium compounds) and, as a potential substitute, Structural Adhesives Primer EW 5000 AS (which does not contain any compounds harmful to the environment). An adhesive film and a sol–gel primer were used to make the joint of two aluminum sheets, and various technologies were used for applying adhesion promoters. The mechanical properties of the prepared samples were tested using two test methods: wedge tests and shear strength tests. In both cases, the samples were aged in laboratory conditions in tap water, and in a climatic chamber (with increased temperature and humidity). The obtained results indicate that the best technology for preparing the joint using each primer is the technology that assumes heating the primer and hardening the adhesive film in one operation. The results of the strength tests indicate that the samples made using the EW 5000 AS primer have higher strength properties under all tested seasoning conditions compared to samples made using the BR 127 primer. It was also confirmed that the presence of moisture and/or water reduces the mechanical strength of the adhesive joints independently of the primer used. The results of the polymer coatings tests to protect the aluminum substrate against corrosion showed that the coatings are only effective for a certain period of time, and, as a result of the NSS test, after 480 h, all the samples were subject to corrosion.

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.

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.

The influence of the storage time on the useful properties (cohesion, adhesion, stickiness) of silicone pressure-sensitive tapes (Si-PSA) was investigated. Two types of silicone resins PSA 529 and PSA 590 (Momentive, USA) were used and crosslinked with bis (2,4-dichlorobenzoyl) peroxide (DClBPO). There was no significant effect of tapes long-term storage (7 years) on their properties. The tapes based on PSA 590 resin were more resistant to aging than PSA 529.