Silikon Elastomerlerin Sönümleme Özelliğini Kontrol Eden Yapısal Parametrelerin Belirlenmesi

Abstract

Silicone elastomers are one of the sytnthetic elastomer used in many areas. Silicone elastomers have many advantages comparison to other elastomers. The main ones are that their properties do not change at high and low temperatures, not affected by climate conditions, and also they show very high insulation properties. Because of this and many such advantages, silicone elastomers often used today in the electrical-electronics sector, automotive sector, food, medicine and construction sector. Sound is a phenomenon that is created by pressure fluctuations. Continuous sound has caused waste of energy in machines. Silicone elastomers also have play a very important role in preventing wasted energy in machines due to their high damping capacity. Aim of this thesis is to identificate of structural parameters controlling damping property of silicone elastomer. Six different silicone elastomer mixtures have been prepared. The vulcanization properties of the mixtures were examined in the moving mold rheometer (MDR) device for 180 oC and 20 minutes. The Silplus 80 has the highest delta torque value, the R752 / 50 has the lowest delta torque according to the results of MDR device. According to the result of tensile test, the maximum elongation was found to belong to R752/50. Silplus 80 and Ravasil 70 also have minimum elongation values. Silplus 80 and Ravasil 70 are harder material and the R752 / 50 is more flexible. The crosslink density was determined by using frequency sweep in the rubber process analyzer (RPA) device. According to the result of frequency sweep, the sample with the highest crosslink density is Silplus 80 and the sample with the lowest cross-link density is R752 / 50, which is 0.0967. The strain sweep was performed to examine the Payne effect on the material. The difference between the largest delta G’ values were observed in the Silplus 70 sample. The difference between the lowest G’ values belong to R752/ 50. A smaller G ' value also means lower Payne effect, stronger filler-polymer interaction and better filler distribution. As a results of thermal gravimetric analysis (TGA), the highest distortion temperature belongs to Ravasil 70 sample and the temperature value is 606.03 oC. The lowest distortion temperature is 532.50 oC which belongs to R752/50. Energy damping properties of silicone elastomers were studied after these basic characterization studies. For this purpose, To observe the compressive behavior of the mixtures, a 10-cycle compression test was applied under 10%, 20%, 30%, 40% and 50% compression ratio. Curves obtained from compression test, the absorbed energy values of the mixtures were calculated and the damping properties of the mixtures were determined. Silplus 80, which has the highest delta torque value on the moving die rheometer, has the highest absorbed energy value. To conclude, it was observed that there was a relationship between the energy damping properties and the structural parameters of silicone, such as hardness and crosslink density, and the energy damping properties. It was concluded that the energy damping property would be increased by increasing the crosslink density. Keywords: Silicone elastomer, payne effect, crosslink density, thermal analysis ,rheology, damping.