Study on off-state characteristics of polyurethane based magnetorheological gels

Magnetorheological gel(MRG) has variable off-state viscosity and it's anti settling performance is very good. Four different ratios of polyurethane based MRGs were prepared (The mass fraction of iron particles was 10%, 25%, 50%, 75%, respectively), and at room temperature (25 ℃) flow characteristics and viscosity characteristics of off-state of samples was tested. The results indicated that both in the rising and falling stages there is a linear relationship between shear rate and shear stress except shear rate above 110 s^-1 of MRG-75. The shear stress increases with the increase of particle content. All samples shown obvious shear thinning characteristics, and the viscosity increases with the increase of particle content. (paper)