Preparation And Study Of Damping Material Based On Silicone Rubber

As the development of modern industry, noise reduction and attenuation ofvibration have become important issues. Viscoelastic materials are widely used in theattenuation of noise and vibration. The loss tangent (tan) can be used as ameasurement of damping properties of materials and that reflects the ability todissipate energy of elastomers. High performance damping materials should meet therequirement of tan>0.3over a broad temperature range of at least60–80°C. Thedamping properties of elastomers are related to the relaxation movement of polymerchain. As a result, elastomers generally exhibit high damping properties in their glasstransition temperature. That is a temperature range far below room temperature andcovers only20~40°C. The focus of the present research is to broaden the temperaturerange with large tan and to improve the damping properties of elastomers at roomtemperature or higher. Silicon rubber is widely used as aviation damping material fortheir excellent resisitance to high and low temperature.Damping materials based on the blending of Vinyl Methyl Silicone rubber(MVQ) and terpene resin are prepared in the present study. Dynamic MechanicalAnalysis (DMA) results indicated that the loss tangent in the temperature rangebetween the glass transition temperatures of the components in the blending increasedapparently despite the separation in the system. Magnetic Resonance CrosslinkDensity Spectrometer, Differential Scanning Calorimeter (DSC) and swelling capacitydetermination are introduced to explore the mechanism of the phenomenon. Theincrease of the content of free chain which is composed of pendant chains and terpeneresin chains results in the enhancement of relaxation resistance and the relaxationdiversification in the frequency range studied The changes of relaxation properties inthe blends are considered to be the reason of the variations in damping properties. Bystudying the influence of the content of terpene and precipitated silica, silicone rubberwith an effective temperature range (tan>0.3) of-40~200°C are prepared.Ethylene Acrylate rubber (AEM) is introduced in the blending system of MVQand terpene resin to increase the mechanical properties of the blends. The ternary blending system has excellent mechanical properties and effective temperature rangeof-7~185°C.Damping elastomers based on hydroxyl terminated poly(dimethylsiloxane) areprepared according to the relaxation mechanism of pendant chains. The influences ofthe molecular weight of PDMS, the structure of the cross-linker and the mole ratio ofcross-linker to PDMS on the damping properties of elastomers are studied in detail.By using PDMS with molecular weight of1.7×104as precursor and tetraethylorthosilicate (TEOS) as cross-linker, silicon elastomers exhibit high dampingproperties from-60~200°C are prepared.