Study On The Preparation And Properties Of Magnetorheological Elasticity Cement

Magnetorheological material, as a kind of magnetic controlled smart material, mainly includes magnetorheological fluids, magnetorheological elastomers, magnetorheological plastomer, magnetorheological grease, etc.. It can be used in vibration isolator and buffer for construction, automotive, medical, military and other fields. However, the defects of magnetorheological materials limit their applications. For the problems of sedimentation, low shear yield stress of magnetorheological fluids, narrow controllable range of magnetorheological elastomers and magnetorheological plastomer, oil separation and poor stability of the temperature of magnetorheological grease. In this paper, based on the preparation of magnetorheological materials, we proposed a new kind of magnetorheological material, magnetorheological elasticity cement(MREC). It adopted elasticity cement as carrier, the main component of which is a high degree of polymerization of linear polysiloxane. And we carried out the relevant studies about magnetic induced properties, preparation technology, mechanical properties, viscoelastic properties. Specific as follows:①Magnetorheological materials and their application prospects were analyzed. To solve problems of magnetorheological materials in the engineering application, a new kind of magnetorheological material which named MREC was put forward. The main component of elasticity cement is a high degree of polymerization of linear polysiloxane.②Based on the microstructure of MREC and field-induced magnetic dipole theory, a model for magnetic induced shear stress of single chain was proposed. And the angle between chain and the magnetic field direction was assumed to be exponential distribution, then the analysis model of magnetic induced shear stress was obtained. It is shown that the magnetic induced shear stress is proportional to the volume fraction of particles, the square of the magnetic field. Other factors such as magnetization characteristic of particle, distribution of particle are also related to the magnetic induced shear stress. Magnetic shear stress increases fast when magnetic particle of1mm~ 5mm,while over 5mm, the effect of magnetic particle on the shear stress is small. The model can be used for the selection of raw materials during the preparation of MREC, and the description of the experimental phenomena.③The selection principle of carrier, magnetic particles and additives were analyzed. Combining with the synthetic technology of MREC and the preparation of magnetorheological materials, twelve kinds of MREC sample were prepared. Infrared spectrum testing, optical microstructure observation, natural sedimentation rate and magnetization properties of MREC indicated that the MREC prepared possessed good dispersion, low remanence and small coercive force, the sedimentation rate was less than 5% after standing 300 days.④Rheological properties of MREC were tested by MCR-301 rheometer. H-B model was adopted to fit the constitutive relation of MREC and identify its constitutive relation parameters. Influence on shear stress by magnetic particle concentration, carrier viscosity, temperature, and magnetic field were analyzed. It is shown that the increase of magnetic particles content, magnetic field, and carrier viscosity can improve the shear stress, while the increase of temperature may lower the shear stress. In addition, when shear rate of 200 s-1, magnetic field of 0~1 T, sample of carrier viscosity 200,000 centipoise and magnetic particle mass fraction of 60%, the shear stress of the adjusting range is 14.1 k Pa to 128 k Pa.⑤The viscoelastic properties of the MREC were tested by using the rheometer of MCR-301 in oscillation shear mode. The relationship between the storage modulus, loss factor and strain, the magnetic field, frequency were analyzed. It is shown that the relative magnetorheological effect of 20wcp20 % sample can reach 1400%. Increasing the magnetic field can broaden the linear viscoelastic region. The linear viscoelastic region in 1T is 20 times of which in 0T. In the linear viscoelastic region, MREC is mainly shown elasticity and storage modulus has nothing to do with the frequency. In the nonlinear viscoelastic region, MREC is mainly shown viscosity and storage modulus is linearly connected with frequency approximation.