Study And Preparation Of A Novel Organosilicone Gradient Damping Material

The main chain of silicone rubber is composed of silicon atoms and oxygen atoms alternately,combining the excellent properties of inorganic molecules and organic polymers,which has attracted the attention of scientific researchers.On the one hand,the bond energy of the Si-O bond(443.5KJ/mol)is higher than that of the C-C bond(335KJ/mol),which makes the silicone rubber have better heat resistance,electrical insulation and chemical stability than other rubbers.On the other hand,silicone rubber has a wide glass transition temperature and can be used as a good matrix.But its low damping coefficient limits its application in the field of damping materials.Therefore,researchers have improved the deficiencies in the damping performance of silicone rubber through chemical or physical modification of silicone rubber.By observing the structural characteristics of natural organisms,a special gradient structure was found.This layered dispersion structure is good for energy dissipation and transmission,so it has better damping effect.Inspired by this gradient structure,in this paper,based on the design principles of bionic gradient structure materials,combined with grafting and compounding methods,a silicone damping gradient material with excellent comprehensive properties is prepared.The main research contents are as follows:(1)The hydrolysis and condensation reaction of diethoxydimethylsilane,phenyltriethoxysilane and vinyltriethoxysilane was used to prepare a linear polysiloxane polymer(PSI).It was grafted and cross-linked with butyl acrylate(BA)monomer to obtain composite material PBA-g-PSI.A new type of silicone gradient multilayer composite was prepared by stacking and assembling PBA-g-PSI with different contents.The effects of polybutyl acrylate content and the number of stacked layers on the damping properties of composite materials were studied.In addition,the thermal stability and thermomechanical properties of composite materials were also studied.The results show that phase separation exists in the gradient multilayer polymer,especially in the three-layer gradient polymer(GM-3)and the four-layer gradient polymer(GM-4)with high PSI and BA content.The peak value of tanδ of GM-4 is 1.43,which is about 55% higher than GM-1(0.92).(2)Using chloroprene rubber,hydroxyl-terminated hyperbranched polyester and silicone rubber as raw materials,an organic silicon gradient multilayer composite material is prepared by a compounding method.The effects of hydrogen bonding,microphase separation structure and gradient structure on the damping properties of composites were studied.In addition,the thermal stability and mechanical properties of materials are also studied.The results show that the gradient structure does effectively improve the damping performance to a certain extent.This is because when the gradient polymer is subjected to external forces,interlayer sliding occurs and consumes a part of the mechanical energy.In addition,there is a hydrogen bond between the hydroxyl groups at the end of the hydroxylterminated hyperbranched polyester(HP102)and the polar atoms on the siloxane backbone.Repeated rupture of hydrogen bonds during dynamic stress is beneficial to energy dissipation.However,the siloxane main chain contains only a certain number of polar atoms.In order to ensure the occurrence of hydrogen bonding,by introducing neoprene latex because the neoprene latex main chain contains a number of polar chlorine atoms that can attract hydrogen atoms.Hydrogen bonding will occur to achieve the intended experimental purpose.The DMA data shows that the tanδmax of the gradient multilayer polymer is 0.186,which is about 118% higher than the tanδmax(0.085)of the SR.