Influence Of Polyurethane Molecular Design And Gradient Structure Construction On Damping Performance

Damping materials can convert mechanical energy into thermal energy under the action of external force,which has the function of vibration and noise reduction,reducing the resonance amplitude of material structure and prolonging the service life of material,and has important application value in modern industry.Polyurethane,as a block copolymer,has the advantages of a wide range of raw materials,high structural designability and excellent controllability of preparation process,which has attracted much attention in the research of viscoelastic damping materials.However,polyurethane elastomers have the disadvantages of narrow glass transition zone(20-30?)and the damping peak value(tan?max)is not high enough,which make it difficult to be directly applied as damping materials.In this study,we prepared polyurethane damping materials with wide temperature range and high damping through molecular design and gradient structure construction to investigate the effects of molecular structure and gradient structure on polyurethane damping performance.The main contents are as follows.(1)The influence of the molecular structure on the damping properties of polyurethane was investigated by varying the type of raw material and the hard segment content.It was found that the PMPU-type polyurethane prepared by MDI/IPDI-PTMG/PPG had the best damping performance at 35.3 wt%of hard segment content,with tan?max reached 0.65 and effective damping temperature range(TR)reached 175.1?(-32.5??142.6?).(2)The effect of different additions of hindered phenol(AO-80)on the damping performance of polyurethane was investigated.As the amount of AO80 added increased,the tan?max of polyurethane increased,and the TR showed a trend of broadening first and then narrowing.Among them,the tan?max of polyurethane sample with AO-80 addition of 5%reached 0.74,and the TR reached 224.0?(-24.0??200.0?),both tan?max and TR were significantly improved.(3)The effect of the introduction of ionic bonds on the damping properties of polyurethane was investigated.The infrared spectral characterization results proved the existence of ionic bonding in the system.A comparative study of the effect of ionic bonding was conducted by static mechanical and dynamic mechanical thermal analysis(DMTA)tests,and the change pattern of the damping properties of polyurethane with different ionic bonding contents was analyzed.It was found that the introduction of ionic bonding enhanced the tan?max and TR of polyurethane materials;with the increase of ionic bonding content,the tan?max of polyurethane showed a trend of first increasing and then decreasing,while the tensile strength was significantly improved,indicating that the introduction of ionic bonding led to the simultaneous improvement of the damping properties and mechanical properties of polyurethane.(4)The polyurethane material with hard segment content gradient without interface and non-composite structure was prepared by the two-component injection method.It was found that the successful construction of the gradient structure enabled the polyurethane to broaden the TR from 40.7? and 66.6?of pure components to 139.5?(-20.6??118.9?)while maintaining a high loss value,and the overall damping performance was greatly improved.