İyonlaştırıcı Radyasyonun Platinle Kürleştirilmiş Silikon Elastomerlerin Kimyasal ve Fiziksel Özelliklerine Etkisi

Abstract

The main purpose of this thesis is to investigate the change in mechanical, dynamic mechanical, and structural properties of platinum-cured VMQ and PVMQ elastomers irradiated with ionizing radiation. Firstly, silicone compounds with different platinum and curing agent ratios were prepared, and the rheological and mechanical properties of these compounds were examined in order to determine the optimum curing agent ratio, as well as the optimum curing temperature and time. Then, the thermally cured VMQ and PVMQ elastomers were irradiated with ionizing radiation in the range of 0-100 kGy. The stress-strain behaviour, hardness, and permanent deformation properties of the irradiated and unirradiated samples were examined to reveal the effect of irradiation on the mechanical properties. To examine the effect of irradiation on damping capacity, cyclic compression tests under static conditions were conducted using a universal testing machine's compression apparatus. The hysteresis curves obtained from compression tests were thoroughly evaluated, revealing how irradiation affects the energy dissipation capacity of both VMQ and PVMQ elastomers under static conditions. Dynamic mechanical tests at different temperatures were applied to all VMQ and PVMQ elastomers by using an Elastomer Test System to examine in detail how the energy dissipation properties change under dynamic conditions. The results obtained from ETS showed the effect of both ionizing radiation and temperature on dynamic mechanical properties. In addition to all these studies, the changes in the dynamic mechanical properties at the natural frequency of both VMQ and PVMQ elastomers with ionizing irradiation were examined in detail using DMYO. Finally, the crosslink density of both VMQ and PVMQ elastomers was calculated using the equilibrium swelling method and it was revealed the changes in the network structures of VMQ and PVMQ elastomers with irradiation. To sum up, it was observed that the main effect of ionizing radiation on platinum-cured VMQ and PVMQ elastomers is to increase the crosslink density. Furthermore, it has been demonstrated that it is possible to selectively alter the mechanical properties of platinum cured VMQ and PVMQ elastomers by using ionizing radiation. Detailed information has also been obtained regarding the effective operating ranges of vibration damping materials prepared using silicone rubbers, such as frequency and temperature, and detailed information has been provided about the changes in damping capacity that may occur when exposed to radiation.