Because of their large surface to volume ration, nanoparticles have a different effect on properties of matrix materials in comparison with the same additives of larger dimensions. In this thesis dynamic-mechanical analysis (DMA) of the unsaturated polyester with the addition of TiO2 nanoparticles was carried out in the temperature range from room temperature to 125 ° C, after which the samples were slowly cooled to room temperature. Within this temperature range the transition from a glassy to a rubbery state takes place in which the module is reduced by two orders of magnitude. The samples were exposed to UV radiation of great intensity for 5 and 15 minutes and by means of DMA analysis the effects of heat and irradiation on modulus of elasticity and on the glass-to-rubbery transition were observed. The changes in the spectrum result from structural changes caused by radiation, as well as the slow heating and cooling during the DMA analysis. It has been shown that the addition of nanoparticles to the unsaturated polyester reduces the modulus at the whole temperature range and at room temperature it drops for 42 % whereas the glass transition temperature decreases for 25 °C. The properties of the composite can vary under the influence of UV radiation and thermal history in which the growth of the modulus and glass transition temperature was observed. Three successive measurements of the non-irradiated and irradiated composites were carried out wherein a large effect of the previous measurement was observed in the second measurement, while in the third run this effect is much lower. This leads to the conclusion that the second heating to 125 ° C and slow cooling leads to saturation.