Membrane Preparation And Characterization Of The Magnetorheological Elastomers

Magnetorheological elastomer (MRE) is a new branch of MR materials whosemechanical property can be changed quickly and reversibly by the application of anexternal magnetic field and can be classified into two groups: anisotropic MRE andisotropic MRE. MRE consists of two main parts: the matrix and the magnetic particle,When applying an external magnetic field to the polymer composite during curing, theinside magnetic particles can be grouped to form chain-like structure, the structure of aMRE can be considered as anisotropic while the other kind can be considered asisotropic without an external magnetic field[1]. So far MREs have been used in tons ofscientific filed owing to their significant advantages and MREs will have morepromising applications.In this paper, we fabricate Polydimethylsiloxane (PDMS) thin films based onMagnetorheological elastomer (MRE) using the spin coating method. PDMS used inthis experiment is non-cross-linked two-part form: base and curing agent (Dow CorningSYLGARD184). Firstly, the PDMS mixture is prepared by adding the curing agent tothe base in a ratio of1:10by weight. Secondly we add the Chloroform to the mixture ina desired ratio of0.5:1and1:1. Finally we add the magnetic particles into theconcentrations in a ratio of15%and20%by weight and then shake the container fortwo minutes with an ultrasonic oscillator until the mixtures are well mixed completely.So we make the thin films after the solution is prepared.Different spin speeds can give us thin films of different thickness, usually the higherthe spin speed is, the thinner the thickness of the films is. The thickness of the films wefabricated is between15-30microns. We observe the microstructure of the anisotropicMRE thin films with an optical microscope and find that they have the chain-likestructure while the magnetic particles are randomly distributed in the PDMS. Beforemeasuring the thickness of the films, we should make a step by cutting a hole in thefilms with a knife so that the profilometer can work well. Then we do the I-V test andget some data to analyze the electronic properties. We find that the mechanicalproperties of the thin films can be tested by the nano-indentor and hope that we can do the nanoindentation experiments in the future to get good experiment data.