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When processing and operating polymer materials under the influence of environmental factors (ultraviolet radiation, moisture, oxygen, ozone, etc.), a change in their properties is often observed. This research is devoted to the study of the effect of chalk additives on morphology and topography, as well as the physical and mechanical properties of samples based on recycled polypropylene raw materials after exposure to UV radiation in air. In order to confirm the occurrence of photo oxidative processes, the data of two methods were used: modified iodometric analysis and IR spectroscopy. The physical and mechanical properties of polymer composites before and after photo aging were determined on standard 1 mm thick blades. To study the surface changes of experimental polymer composites under the influence of ultraviolet radiation, atomic force microscopy was used. The result of the experiment is the proof that the chalk additive interferes with the intensive course of photo-oxidative degradation. In general, the introduction of a chalk additive in a small amount (2 to 10 weight parts) allows maintaining the strength characteristics of composites based on recycled polypropylene raw materials after exposure to UV radiation in air, probably because of crosslinking of macromolecules due to the intermolecular interaction of hydro peroxide groups accumulated by the polymer, as well as involving only surface layers of composite samples in the photo oxidation process. Moreover, the analysis of AFM images of samples subjected to ultraviolet irradiation for 18 hours shows that the surface becomes smoother. This is confirmed by the calculation of the root mean square roughness and the maximum height of the roughness. Further irradiation for additional 18 hours leads to an increase in roughness, which indicates a change in the supra molecular structure in the surface layers of polypropylene as a result of photo oxidative transformations. Therefore, from the obtained composites, one can expect the maintenance of operational characteristics during the period of consumption, followed by decomposition under the influence of environmental factors.

Recently, the development of modern technology for producing biodegradable polymers is one of the most topical issues. Filling the polymer with natural components increases the interfacial contact boundary, through which moisture and aggressive chemicals can penetrate into the material, which accelerates the decomposition of the composite in natural conditions. This study is devoted to the study of the thermophysical properties of biodegradable composite materials based on recycled polypropylene with various natural fillers of plant origin. In this work, we measured the thermal conductivity and resistivity depending on temperature, filler concentration and residence time in the recovered soil in which the samples were biodegraded, shows the relationship between the change in thermal conductivity and resistivity of the studied samples and proposed preliminary conclusions about the mechanisms of thermal conductivity of the materials considered. Adding natural fillers of plant origin to composites based on recycled polypropylene gradually increases the thermal conductivity coefficient with increasing filler content. In this case, the resistivity decreases, and, with an increase in the content of the filler, this decrease becomes more significant. This means that with an increase in conductivity, the coefficient of thermal conductivity also increases, which is typical for materials in which charge transfer occurs at the expense of electrons. As a result of destruction under the influence of the environment, the thermal conductivity of the samples decreases, and the change is most significant for samples with a high content of filler.

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