Introduction. The disposal of automotive tires typically involves landfilling, stockpiling, or incineration. As a result, this causes soil and atmospheric pollution. Scientists have long and actively discussed the recycling of tire rubber as one of the approaches to solving environmental problems. It is known that the use of rubber crumb in composites can reduce their weight and thermal conductivity. However, materials based on unsaturated polyester containing rubber waste have been insufficiently studied. There are contradictions in the assessment of their mechanical and thermal insulation properties. Moreover, the optimal rubber content in the composite is unknown. The presented work addresses these gaps. The research objectives include the development and analysis of new materials based on unsaturated polyester with justification for the required proportion of rubber waste.

Materials and Methods. During the processing of tire rubber, a multistage grinding process was carried out, followed by magnetic and air separation. A powder with a density of 500 kg/m³ was obtained. The minimum particle size was 0.1 mm, and the maximum was up to 1 mm. The composite matrix was unsaturated polyester with a density of 1160 kg/m³. To fabricate the specimens, 0, 10, 20, 30, 40, and 50% rubber filler were added to it. Stable geometry was achieved through curing at room temperature and subsequent mechanical processing. For each composition, three specimens with an area of 0.021 m² and a thickness of 0.01 m were produced.

Results. The dependence of density, water absorption, and thermal conductivity of the samples on the volume of recycled tire rubber was shown. As its proportion increased, a noticeable decrease in density was recorded: at 0% — 1160 kg/m³; at 10% — 1074.3; at 20% — 1037.2; at 30% — 1017.8; at 40% — 963.7; at 50% — 905. Water absorption dynamics were determined by the weight of the samples after immersion in water. It took more than 8 hours for changes (even minor ones) to occur. The indicator in percentage terms increased from 0.024% to 0.47%, meaning the absolute maximum was <0.5%. As the rubber content increased, thermal conductivity decreased. The value for pure polyester was 0.254854 W/(m·K); for the composite with 10% rubber — 0.2510574; with 20% — 0.245156; with 30% — 0.238484; with 40% — 0.223062; with 50% — 0.207039. All samples withstood a load of 1300 kN.

Discussion. The incorporation of 50% rubber into unsaturated polyester results in a 22% reduction in sample density and a 19% decrease in thermal conductivity, with water absorption remaining under 0.5%. These properties suggest the suitability of the composite as an efficient insulation material, even in environments with elevated humidity. Its high compressive strength (>61.83 MPa) allows for its use in structures subjected to significant loads. Varying the rubber content will provide an optimal balance between mechanical properties and moisture resistance.

Conclusion. This work presents an approach for the sustainable recycling of tires to produce effective insulation materials. Promising directions for future study include investigating composites with larger rubber particles (>1 mm), evaluating their acoustic insulation properties, and assessing their fire resistance and chemical stability.