Preparation And Properties Test For Ploysiloxane Based Magneto-rheological Viscoelastic Materials

In our daily life, impact lives everywhere. The existing passive energy-absorbingcushioning devices cannot adjust the parameters of cushioning device according to thetype of impact strength and impact loads to protect the device structural health andsafety personnel. The mechanical properties of magneto-rheological material arecontrolled by magnetic field, the magneto-rheological buffer device can bring newsolutions for shock loading buffer. But the defects of the existing magneto-rheologicalmaterials limit the application of the field of shock absorber. From the problems of thepoor static stabilities of the magneto-rheological fluid, the temperature stability andcarrier separation of the magneto-rheological grease and the controllable narrow rangeof the magneto-rheological elastomer to be solved, the practical significance andacademic value of the paper is proposed.In response to these problems, combined with the characteristics of the linearpolysiloxane, a new magneto-rheological material, named magneto-rheologicalviscoelastic material (MRVM), based linear polysiloxane is proposed. Specific asfollows:(1) The engineering application in the field of impact load buffer and researchtheory under high speed of magneto-rheological materials were expounded. It is shownthat magneto-rheological materials have a broad development prospects in the field ofimpact load buffer. The shortcomings for preparation technology of currentmagneto-rheological materials and impact load buffer were analyzed. In order to solvethe above problems, and combine with the characteristics of linear polysiloxane, a newmagneto-rheological material based linear polysiloxane is proposed.(2) The characteristics of the linear polysiloxane were analyzed, the preparationtechnology and experiment device of MRVM were expounded, and selection principlesof magnetic particles were analyzed. Carbonyl iron powder of BASF-SQ series wasselected as the disperse phase. Surfactant and thixotropic agent were selected to dealwith the surface of the magnetic particles, and then12samples were prepared by ballmill dispersion. The microscopic dispersion morphology was observed throughVHX-600electron microscope, it is found that magnetic particles disperse evenly in thematrix, and have no harden.(3)Common test principles of rheological properties were compared and analyzed. The relationship of the plate rheometer between shear stress and torque, shear rate wasdeduced. The steady-state mechanical properties and dynamic mechanical properties ofMRVM were tested bythe rheometer of MCR-301, and the settlement of its stability wasobserved. It is shown that the content of carbonyl iron powder is a major factor for shearyield stress, the first differential stress, of magneto-rheological viscoelastic material.Thehigher content of carbonyl iron powder, the adjusting range and magnification ofmagnetic field is wider, but the relative adjustment ratio of elastic modulusdecreases.Molecule polymerization degree of substrate and the content of carbonyl iron powderdecide the initial viscosity of magneto-rheological viscoelastic materials. The adjustingrange of shear yield stress is14.1~128kPa under shear rate200s-1, magnetic inductionintensity of0~1t. H-B model was used for describing the constitutive relations and theparameters of the model was identified. There is noobvious sedimentation after6months observation. Magnetic field can broaden the linear viscoelastic area ofmagneto-rheological viscoelastic materials. In the linear area,0~80Hz frequency haveless impact on the dynamic mechanical properties.(4) The magnetization characteristics of MRVM-20wcp were tested by HH-15vibration sample magnetometer. The magnetization characteristics of the selectedcarbonyl iron powder and carbonyl iron powder manufactured by xx company wascompared. It is shown thatMRVM contain more carbonyl iron powder has the higherspecific magnetization（higher saturation magnetization）. Selected carbonyl ironpowder is with high saturation magnetization, low coercive force, which shows that theselected dispersed phase of carbonyl iron powder is reasonable.(5) Summarize the research work and the characteristics of this paper, and expoundthe problems need to be further studied in this paper.