Preparation And Properties Investigation Of Organic/Inorganic Doped Polyether Polyurethane Low Damping Materials

Polyurethane elastomer has many excellent properties,which is widely used in industry and daily life.When it is used as damping material,it is required to have high dissipation factor and wide damping temperature range.In cold areas,the different parts of snowboards and other polar skiing equipment(such as board and track)often require different damping property to satisfy various applications.Generally,the application of polyurethane elastomer in these equipments should fufill the following conditions:the working temperature is within-40?-5 ?,the glass transition temperature is low,and the loss factor is less than 0.3.The damping factors of polyurethane elastomer should be adjustable when it is used in different parts of skiing equipment and snow transport.Therefore,the proprty of polyurethane elastomer should be modified to satisfy the requirements of using in cold areas.In this thesis,the low damping polyether polyurethane materials doped with ultraviolet absorber,rubber vulcanization accelerator(DZ)and multi-wall carbon nanotubes were prepared by solution blending method combined with the rapid cooling process,furthermore,the damping properties,mechanical properties and storage stability were systematically studied.It provides theoretical basis for design and synthesis of polyurethane elastomer.Dynamic mechanical thermal analysis(DMA)tests prove that for binary low damping materials doped with UV absorbers(THUV-328 or UV-329),with increasing content of the UV absorbers,the glass transition temperature(Tg)and loss factor of the binary low damping material gradually decreased to-28.6?(THUV-328),-25.2 ?(UV-329)and 0.15(THUV-328),0.14(UV-329),respectively.The storage modulus is gradually increased with the increase of THUV-328(or UV-329)content.For THUV-328 doped materials,when the testing temperature is higher than 30?,the loss factor of the binary low damping material increases as the doping amount increases.For UV-329 doped materials,when the testing temperature is higher than 20?,the loss factor of the binary low damping materials firstly flattens and then rises as the doping amount increases.The results show that as the THUV-328(or UV-329)content increases,the dopants in the composite system transform from plasticization to fiber-like reinforcements.The results of DSC,FTIR and SEM show that THUV-328 exists in the matrix in the form of micron-sized short fibers,and there is no hydrogen bonding between the matrix and THUV-328.The UV-329 exists in the matrix in a micron strip shape,and there is a weak hydrogen bonding between the matrix and UV-329.The SEM results show that the compatibility of UV-329 and the matrix is better than that of THUV-328 and the matrix,resulting from the low migration of UV-329 small molecules in the system.Tensile tests show that as the doping amount increases,the elastic modulus increases when the binary low damping materials is under low strain conditions(elongation is less than 10%).When the binary low damping materials is at high strain(elongation is higher than 250%),as the doping amount increases,the tensile stress is reduced(THUV-328 doping)or remains unchanged(UV-329 doping),but the plasticity of the both materials is enhanced.For the ternary low damping materials doped with UV absorber(THUV-328 or UV-329)and accelerator DZ,the effect of accelerator DZ on the damping properties and mechanical properties are studied with fixed UV absorber content.The results show that the damping performance of the ternary system changes with the variation of proportion of UV absorber and accelerator DZ.When the THUV-328 content is fixed,the maximum loss factor of the ternary low damping materials in the temperature range of-40?-5 ? has no obvious change.When the UV-329 content is fixed,the maximum loss factor of the ternary low damping materials in the temperature range of-40?-5? increases firstly and then decreases with the increase of the doping amount of the accelerator DZ.The results of FTIR,DSC and SEM tests show that,the above damping results are mainly caused that there is an intermolecular force between adjacent DZs,and between DZ and the matrix in the ternary system,in which the force belongs to effect of the secondary bond.This indicates that DZ exists in the ternary system in the form of independent particles,or combined with the matrix,or aggregated into clusters.Therefore,in the ternary system,by adjusting different ratios of the accelerator DZ and the ultraviolet absorber(THUV-328 or UV-329),damping values which actually required in the temperature range of-40? to-5? can be obtained.For quaternary low damping materials composed of polyether polyurethane,UV absorber(THUV-328 or UV-329),accelerator DZ and multi-walled carbon nanotubes,the doping of multi-walled carbon nanotubes in the system can reduce the glass transition temperature and loss factor of the materials(maximum loss factor can be reduced to 0.18).The tensile properties test shows that the mechanical properties of the material are enhanced when the system is doped with carbon nanotubes.The SEM results show that the small molecule content of the quaternary low damping materials doped with UV-329 is higher than that of the quaternary low damping materials doped with THUV-328.The reason is that THUV-328 and DZ are easy to combine with carbon nanotubes in the system,resulting in relatively lower content of THUV-328 and DZ at the fracture surface.However,UV-329,DZ and carbon nanotubes are well dispersed in the quaternary system,resulting in high content of small molecules at the fracture surface.The different composition of damping materials results in different storage stability.The results show that there is no chemical change or appearence of hydrogen bonding in the accelerated aging process of ternary and quaternary low damping materials.The changes of thermal behavior,damping performance and mechanical properties happened due to the migration of small molecules to the surface layer.In ternary system the instability of low damping materials after aging is mainly caused by the precipitation of small molecular particles and the redissolution of the precipitated small molecular particles to the system.In the quaternary system,the main reason is that the network structure formed by carbon nanotubes hinders the migration of small molecules.In summary,the difference of the damping properties and mechanical properties of the material after accelerated aging is determined by the environment,the external influencing factors(such as force,time,etc)and the raw material itself.