Low Frequency Damping Polyurethane Materials:the Preparation And Characterization

Vibration on the one hand affect the accuracy of equipment,for some military facilities such as submarines,the noise from vibration is easy to be detected by detection equipment on the other hand.Hence,high damping materials are essential for vibration and noise reduction.The increasing requirement of precision and concealment of equipment calls for excellent damping materials in various frequency bands.Polyurethane is one of the widely used damping material,however,its damping performance of low frequency vibration has not been reported yet.Current study focus on the response of frequency to damping performance of polyurethane,the influence of the structure at the molecular level and the interaction between filler and polyurethane on damping performance in the low frequency region was discussed.The research contents are as follows:(1)Relationship between molecular structure and damping properties of polyurethane.2,4-toluene diisocyanate(TDI),diphenylmethane-4,4-diisocyanate(MDI)were selected as the hard phase,while polyether polyol(PPG2000)and polyester polyol(FA2817p)as the soft phase,tuning the damping performance by designing the hard and soft phase of the molecular structure.The results showed that the maximum loss factor obtained in the low frequency band(0～1Hz)of the polyurethane with MDI as hard segment and polyester polyol(FA2817p)as soft phase can reach 0.46.It was further found that MDI/FA2817 p polyurethane system can form hydrogen bonds in the molecule because of the soft end ester group,thus improving the viscosity of the substrate and therefore enhancing the damping performance of polyurethane composites(2)The relationship between inter-molecular hydrogen bonds and damping properties of polyurethane.Selecting the phenolic compound AO-80 as filler.The effects of different mass fractions of AO-80 on the damping properties of polyurethane were studied.The results show that the maximum loss factor of MDI/FA2817p/20%AO-80 polyurethane can reach0.87 in the low frequency band of 0～1Hz.The maximum loss factor of MDI/L3010/50%AO-80 polyurethane can reach 1.4 in the frequency band of 1～200Hz.Through the formation of hydrogen bond between AO-80 and polyurethane,the dissociation/reconstruction of hydrogen bond under vibration is conducive to the consumption of vibration energy and the improvement of damping performance.(3)The influence of piezoelectric effect on damping performance of polyurethane.Using piezoelectric PVDF as the second phase.The PVDF/PU blends nanofiber membrane,and PVDF@PU shell core structure composite fiber membrane were prepared by electrostatic spinning,comparing with solution blends PVDF/PU membrane.It was found that polyurethane core-shell fiber materials prepared by coaxial spinning showed better damping performance owing to strong interface effect of the composite materials,which enables micro-phase separation and thus improves the damping performance of materials.In this study,the structure,filler and piezoelectric damping of polyurethane materials were demonstrated,which provides a new way for low frequency damping materials designing.