The polymer processing industry is paying more attention to biodegradable materials synthesized from renewable sources. One of the most popular of them is polylactide (PLA). Except the material from which a given product is made, particularly important is the process of manufacturing a polymer material, processing, use by the consumer, and finally, recycling it. Neither of these steps is indifferent to the environment. The processing of polymers can often lead to material degradation, which affects the properties of the material and leads to the generation of substantial amounts of post-production waste that cannot be reused by processors. The aim of this work is to evaluate selected properties of PLA subjected to the extrusion process under variable extrusion conditions. This is important due to the large losses of material and energy resulting from the extrusion of biodegradable polymers under poorly selected processing conditions, which, apart from the economic effects, has a negative impact on the environment. The research proved that both the temperature and the structure of the plasticizing system as well as the rotational speed of the screws affect the mechanical properties of the final product. For PLA optimization, this process will directly contribute to the improvement of the PLA processing process, and indirectly help to act for the benefit of the environment by reducing the consumption of energy, raw materials, and the amount of post-production waste. The obtained results allowed for the selection of appropriate parameters depending on the expectations regarding the properties of the final product. The conducted research will help to optimize processing processes and reduce the consumption of raw materials, which in the future will also affect the environment.

The aim of this study was to ascertain whether the combined action of metal nanoparticles (silver, copper, zinc oxide, iron oxide) would ensure the appropriate biocidal properties oflow-density polyethylene (LDPE) against pathogenic microorganisms. According to the research hypothesis, appropriately selected concentrations of the applied metal nanoparticles allow for a high level of biocidal activity of polymeric materials against both model and pathogenic bacterial strains (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Legionella pneumophila, Salmonella enterica subsp. enterica) and fungi (Aspergillus brasiliensis, Saccharomyces cerevisiae, Candida albicans, Penicilium expansum), whilst ensuring the safety of use due to the lack of migration of particles to the surrounding environment. Studies have shown that adding 4% of a biocide containing Ag, Cu, ZnO, and Fe₂O₃ nanoparticles is the most optimal solution to reduce the number of S. aureus, S. enterica and P. aeruginosa by over 99%. The lowest effectiveness was observed against L. pneumophila bacteria. As for E. coli, a higher biocide content did not significantly increase the antibacterial activity. The results showed a high efficiency of the applied biocide at a concentration of 2% against fungal strains. The high efficiency of the obtained biocidal results was influenced by the uniform dispersion of nanoparticles in the material and their low degree of agglomeration. Furthermore, a slight migration of components to the environment is the basis for further research in the field of the application of the developed materials in industry.

This study investigated the influence of commercially available food preservatives: Natamax^® (containing natamycin) and Nisaplin^® (containing nisin) on the antimicrobial properties of LDPE film, commonly used for food packaging. Studies have shown that the addition of 3% Natamax^® or, alternatively, the addition of 5% Nisaplin^® provides an LDPE film with effective antimicrobial protection. The applied biocides did not significantly affect the strength and rheological properties of LDPE. However, differences in optical properties were observed. The transparency of the samples decreased slightly with the addition of 3% or 5% Natamax^® (by approx. 1% and 3%, respectively). A significant change was observed in the film haze, the addition of 5% Natamax^® increased this parameter by approx. 80%, while 5% Nisaplin^® increased it by approx. 19%. Both Natamax^® and Nisaplin^® agents can be successfully used to manufacture food packaging materials with antimicrobial protection. Natamax^® showed a stronger bactericidal effect, while Nisaplin^® changed other properties less significantly.