The objective of this study is to determine selected properties of thin-walled rotationally moulded composite parts. Linear low-density polyethylene (LLDPE) filled with quartz flour (QF, 5–35 wt.%) was tested. High-density polyethylene functionalized with maleic anhydride (HDPE-g-MA) was used as a compatibility agent. Polymer samples were prepared with and without the compatibility agent (2 wt.% in relation to the QF content). The study investigated the effect of QF content and HDPE-g-MA on the properties of rotationally moulded parts, including their melt flow rate (MFR), thermal properties (DSC and TGA), thermomechanical properties (VST), mechanical and physical properties, microstructure, and geometry. Results showed that the properties of LLDPE/QF with HDPE-g-MA were significantly higher than those of LLDPE/QF without HDPE-g-MA. It was also found that the compatibility agent improved the composite material’s thermal stability. This improvement was attributed to interactions occurring between the composite material components due to the use of the compatibility agent. In addition to that, microscopic examination demonstrated that the use of HDPE-g-MA improved miscibility of the composite material components. The composite samples containing HDPE-g-MA had better surface geometry.

The extensive research on polymer composites is motivated by the fact that it can result in obtaining new materials with enhanced properties. This research primarily focuses on investigating basic mechanical properties which determine the use of a particular composite material. This paper presents the results of tests investigating the mechanical properties, i.e. tensile strength, hardness and impact strength, of hybrid injection mouldings produced at constant processing parameters. We used five metal powder fillers: aluminium, zinc, tin, iron and copper powders, with their contents ranging from 2.5 wt% to 15 wt% relative to a polypropylene matrix composite material. The relationships were determined between different contents of the aforementioned metal powder fillers and Young’s modulus, maximum tensile stress, tensile stress at break, strains, Shore hardness and Charpy impact strength. The research also involved investigating mould shrinkage. Relevant conclusions were drawn.

The paper presents the results of research on hybrid composites made of unsaturated polyester resin based on post-consumer recycled poly(ethylene terephthalate). The polymeric materials were reinforced with quartz flour, which is a common inorganic mineral filler. An environmentally friendly cobalt polymer solution was used to cure the polyester matrix. The results showed the quantitative influence of the quartz filler on the thermal, mechanical and morphological properties of the quartz–polyester composites. A change in the surface wettability and the polarity of the polymeric materials was also noticed, with some deterioration of their gloss.

This paper deals with rotational moulding. The relationship between mould speed and wall thickness in the upper, middle and lower areas of rotational moulded parts is investigated. Young’s modulus of moulded parts is determined via static tensile testing. A static compression test is performed to determine the maximum compressive force causing strain. The test is conducted on the wall of moulded parts, parallel to the main axis of rotation. Also, energy consumption in rotational moulding is investigated for different rotational speeds of the mould. Moulded parts are made of DOWLEX®2629UE linear low-density polyethylene (LLDPE). Experimental results are statistically analysed using STATISTICA 13. Non-parametric statistical tests are used for results analysis. The ANOVA method is employed to determine if there are any significant differences between obtained results. The statistical tests show that the range is much narrower for a speed ratio of 4:1. The narrowest range value is obtained for 12 3 rpm. The highest Young’s modulus values are obtained for the parts moulded at 12 3 rpm (1263.33 MPa) and 16 4 rpm (1263.67 MPa). The highest maximum compressive force is obtained for the parts moulded at 12 3 rpm (10 400 N). An analysis of the results demonstrates that the part moulded at 12 3 rpm has the most advantageous properties. For this mould speed, the power consumption amounts to 8.28 kWh. Experimental results and statistical analyses demonstrate that mould speed affects both moulded part quality and energy consumption in the rotational moulding process.

The paper presents the results of research on composites containing wood flour and vinyl ester resins as matrices. One of the resins was a commercially available vinyl ester resin (VER) based on bisphenol A, while the other (VPE)—not containing bisphenol A, was obtained by us in an innovative way protected by a patent, whereas light yellow wood flour (WF) powder was obtained from spruce (Picea) and fir (Abies). Due to the fact that vinyl ester resins are characterized by large mechanical and chemical resistance, they are used mainly in the form of composites for the production of everyday products. To verify the possibilities of their biomedical applications, our studies focused on the evaluation and comparison of cytotoxicity of both resins using human skin fibroblasts and their resistance to bacterial bio-film adhesion for the aerobic Gram-positive bacteria Staphylococcus aureus ATCC 25923, Enterococcus faecalis PCM 896 (Polish Collection of Microorganisms), and the aerobic Gram-negative bacteria Escherichia coli ATCC 25992.