Preparation And Properties Of Electromagnetic Shielding Functional Polyurethane Damping Material

The operation of mechanical equipment will produce vibration and noise.For a long time,damping materials have been continuously developed and applied to achieve the purpose of shock absorption and noise reduction,with the development of human industry and the progress of science and technology,more and more electronic devices are widely used in mechanical equipment in the fields of automobiles,ships,aerospace and others.These electronic devices will be seriously interfered by electromagnetic radiation,and the stability and safety of the equipment will be threatened.Therefore,developing a new material with electromagnetic shielding and good damping performance is an effective way to solve the above problems.Polyurethane is a flexible,designable,oil-and wear-resistant damping material.However,it is difficult to meet the problems of wide damping temperature range and good mechanical properties of single component polyurethane material.Based on the above background,a polyurethane damping material with electromagnetic shielding function was prepared in this thesis.Fourier transform infrared spectroscopy（FTIR）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）and X-ray photoelectron spectroscopy（XPS）were used to characterize the synthesis and preparation of the damping materials and fillers.The damping properties,crystallization properties,thermal properties,electromagnetic shielding properties and mechanical properties of the materials were analyzed by dynamic thermomechanical analysis（DMA）,X-ray diffraction（XRD）,thermogravimetric analysis（TG）,electromagnetic shielding performance test（EMI）and universal tensile test.The main contents are as follows:（1）Epoxy-terminated hydroxyl polybutadiene（EHTPB）,diphenylmethane diisocyanate（MDI）and 1,4-butanediol（BDO）were used as raw materials to synthesize polyurethane material（EPU）with epoxy groups in the main chain.By changing the R value,the damping and mechanical properties of EPU were tested,the influence of R value on the properties of EPU material was explored,and the best raw material ratio was determined.When R=2.0,the comprehensive performance of EPU is the best,tanδextreme value is 0.91,effective damping temperature range is 35.8℃,tensile strength is8.5 MPa,and elongation at break is 267.1%.（2）Modified basalt fiber（MBF）was synthesized by surface treatment of basalt fiber（BF）withγ-aminopropyl triethoxysilane（KH550）.Then MBF and EPU were connected by chemical bonding to make EHTPB/modified basalt fiber damping material（EPU/MBF）,Compared with pure EPU and polyurethane material with unmodified BF（EPU/BF）,the damping and mechanical properties of the material were tested.The results show that compared with pure EPU,the damping performance and mechanical properties of EPU/MBF are improved to a certain extent.Among them,the effective damping temperature range of EPU/10MBF is increased the most,reaching 85.4℃,while the tensile strength and elongation at break are increased by 7.7%and 24.9%respectively,which has the best comprehensive performance.（3）The MAX phase material Ti₃Al C₂was etched with hydrofluoric acid（HF）to prepare MXene materials.SEM,TEM,XRD were used to characterize MXene.By adding different contents of MXene to EPU/10MBF（BFEPU）,the damping material with electromagnetic shielding function was successfully prepared,and the electromagnetic shielding,damping and mechanical properties of the material were tested.The results show that the damping materials with electromagnetic shielding function were successfully prepared,and the composites with 12 wt%MXene addition had the best electromagnetic shielding performance.In the test range of 8.2-12.4 GHz,The EMI-SE_Tof the materials reached 22.7 d B in the test range of 8.2-12.4 GHz,the damping property of the composite decreased slightly with the addition of MXene.The tanδextreme value of BFEPU@12MXene is 0.53,and the effective damping temperature range is 112.3℃.The mechanical properties of BFEPU@4MXene are slightly improved,the tensile strength and elongation at break are 9.2 MPa and 295.3%,respectively.