Indentification of the factors controlling the relaxation behavior of silicone elastomers

The main purpose of this thesis is to examine the parameters controlling the relaxation properties of silicone elastomers prepared using vinyl-methyl-polysiloxane (VMQ). For this purpose, the speeds of the rotors used in the mix and the mixing time values have been tried to be optimized so that the mixture to be prepared in the first stage is homogeneous and chain cutting is not experienced. The mixtures were prepared in a lab-type torque rheometer mixer with a banbury type mill. A number of mixtures were prepared using different types and proportions of peroxide. The compound obtained in the second step were cured at different temperatures using the Moving Die Rheometer (MDR). The rheological parameters of the rubber were determined from the obtained torque-time graphs. The rheometer curves were analyzed at first degree by kinetic model and the effect of vulcanization temperature on the vulcanization rate and the effect of peroxide type, peroxide ratio on the activation energy of vulcanization were elucidated. Then the compound are cured using the hot press at the temperatures and times determined by the obtained rheological information. In the next step, the crosslink density of the samples was calculated using Pulse-NMR technique. In addition, the relaxation behaviors of cured elastomer were observed using the Temperature Scanning Stress Relaxation (TSSR) technique. Physico-mechanical tests and aging tests in different aqueous media were applied to these samples cured at the last stage of the thesis. Factors controlling the aging stability of elastomers have been identified.