This work is aimed at evaluating the effects of weathering on the surface properties of plastic materials intended for outdoor use. Changes in contact angles, surface energy, thermal stability and hardness were compared before placement in a test chamber, after a 288-hour test according to ASTM G 154-00a and after 6 months in a real atmosphere. Samples made of polypropylene (PP), polyethylene (PE) and a combined plastic of polypropylene and polystyrene (PP+PS) were used. The results of the thermal analysis show that the least stable material was PP, where the thermal stability decreased by more than 1.4 °C after 288 hours in the test chamber. The most thermally stable sample was the sample made of the combined plastic PP+PS. The hardness of the sample made of PP+PS was also the highest of the samples studied. From the obtained values ​​of contact angles and surface energies for individual samples, we can conclude that there were no significant changes in the values ​​in the test chamber after 288 hours. However, significant changes occurred when comparing the samples before and after exposure to real weather conditions for 6 months. The surface of the samples changed to hydrophilic. From the obtained data, we can conclude that the plastic sample combination of polypropylene and polystyrene (PP+PS) is the most suitable of the investigated materials, because it achieved the highest thermal stability and the highest hardness. Also, from an economic point of view, it was the most advantageous and there were no visible changes on its surface even after exposure to direct atmospheric conditions and accelerated weather conditions.

Acknowledgement: The work was supported by the project KEGA 008TnUAD-4/2025.