İyonlaştırıcı Radyasyonun Farklı Ajanlarla Kürlenmiş Poli(Epiklorohidrin-Ko-Etilen Oksit-Ko-Allil Glisidil Eter) (Geco) Bazlı Elastomerlerın Enerjı Sönümleme Özellikleri Üzerindeki Etkisinin Araştırılması

Abstract

Epichlorohydrin-based rubbers are polymers developed as an alternative to butyl and chloroprene rubbers and have been increasingly used in recent years due to their superior properties. Compared to many other rubber systems, they are preferred due to their higher oil, fuel, ozone and chemical resistance, high heat resistance, as well as high vibration absorption and damping properties, and their usage area is gradually increasing. In previous studies, as a result of irradiation of poly(epichlorohydrin-co-ethylene oxide-co-allyl glycidyl ether (GECO) terpolymer in pure form without the addition of curing chemicals and other additives, it has been proven that GECO is a polymer with a tendency to cross-link with radiation. In this study, firstly, curing conditions of the terpolimer (poly(epichlorohydrin-co-ethylene oxide-co-allyl glycidyl ether) prepared with ethylene oxide and allyl glycidyl ether of epichlorohydrin) were determined with different curing chemicals, the structural changes of the cured GECO polymers were investigated, and the change in the energy absorption property was investigated. As a curing chemical, 0.8,1.2,1.6 phr 2,4,6-Trimercapto-s-triazine (TMT) and 0.8,1.2,1.6 phr hexamethylene diamine carbamate (HMDAC) were used, and the changes in physical and chemical properties of GECO elastomers as a result of changing the amount of cure agents were analyzed. For this purpose, dynamic mechanical properties of elastomers, stress-strain behavior, mechanical compression tests to determine their energy absorption capacity and temperature scanning stress relaxation properties for determination of service temperatures and swelling tests and lunar structure properties are clarified. As a result of the studies, it was determined that the cross-link density, hardness value and energy absorption capacity of elastomers increased due to the increase in the ratio of cure chemicals in both TMT and HMDAC systems. Crosslink densities calculated with TSSR measurements and the Money-Rivlin method; T3108-TMT08 < T3108-HMDAC15 < T3108-TMT12 < T3108-HMDAC25 < T3108-TMT16 < T3108-HMDAC40. It has been observed that the energy absorption capabilities increase depending on the increase of TMT and HMDAC cure chemicals, and the hysteresis losses per energy loaded into the system (Relative hysteresis loss) increase slightly depending on the amount of both TMT and HMDAC cure agents, but this difference is very small. In the literature, it was determined that there is no GECO elastomer’s polymer-solvent interaction constant(χ). In this thesis study, theoretically, this constant value was found to be 0.571 for acetone solvent by the group contribution method, and a contribution was made to the literature. Polymer-solvent interaction constants(χ) were calculated from the Flory Rehner equation using the equilibrium swelling polymer volume fractions (V2m) and crosslink density values obtained from TSSR of the GECO elastomers for which swelling experiments were performed in acetone solution. Compared to the unmodified GECO elastomer, it was found that the crosslink density increased and the polymer-solvent interaction constant(χ) of GECO elastomers containing TMT and HMDAC, which used various additives, increased, this result was found to be compatible with the changes that occurred on elastomers. In the second stage of the study, to determine the effect of ionizing radiation, which is another method used to improve crosslinking and structural properties in polymers and to prepare materials with superior properties, on crosslinked GECO elastomers, the prepared elastomers were exposed to ionizing radiation in the dose range of 0-100 kGy.Ionizing radiation has two main effects on polymers: chain scission and cross-linking. In order to understand how these structural changes affect the epichlorohydrin-based GECO polymer, the cured elastomers were irradiated with electron beams. As a result of the studies, it was observed that irradiation for GECO elastomers had a dominant effect in the cross-linking direction., Depending on this change, when a comparison is made from the mechanical test results by taking into account the same elongation values, the elastic modulus values increase as the irradiation dose increases, the crosslink densities increase depending on the irradiation dose, but the chain shear tendency also creates error points due to irradiation and/or ruptures as a result of the hardening of the structure. An exception to this situation was the T3108-TMT12 elastomers, the breaking strength values of these elastomers increased as the irradiation dose increased. The possible reason for this is that the increase in the amount of TMT, the cross-linking of T3108-TMT08 elastomers increases and a more homogeneous cross-linked structure is obtained with high cross-linking with irradiation. GECO elastomers which irradiated at different dose rates and non-irradiated sample, were compared, it was determined that the energy absorption capacity increased with increasing irradiation dose. As a result of all these studies, it has been proven that both mechanical and dynamic mechanical properties and damping properties of GECO-based polymers can be changed in a controlled manner depending on the structure and ratio of the curing TMT and HMDAC systems, and the ionizing radiation and the dose adsorbed during radiation treatment.