Synthesis and characterization of magnetorheological polyimide gels

Abstract

Magnetorheological polymer gels (MRPGs) are composite fluids containing ferrous particles suspended in a polymer gel. In addition to modification of the carrier fluid, the polymer gel, which includes crosslinked copolyimide (CCPI) and solvent N-octylpyrrolidone, also changes the surface properties of the ferrous particles, thus reducing the particle settling and improving particle redispersion. The viscosity of MRPGs can be easily adjusted by controlling the concentration of CCPI in the carrier medium. High thermally resistant CCPI is synthesized from dianhydride, diamine, diaminobenzonic acid, and crosslinker and has a high glass transition temperature because the crosslinking ratio can be controlled by the molar ratio of diamine to diaminobenzonic acid. The redispersion and rheological properties are also investigated.

Study on the properties of magnetorheological gel based on polyurethane

“…As the addition of magnetic particles, the material shows non‐Newtonian behavior and higher viscosity. This result is in a good agreement with Fuchs' report 22…”

“…This result is in a good agreement with Fuchs' report. 22 From this figure, it can also be seen that the viscosities of PU MRG samples decreased with the increment of NCO/OH ratio. This result is due to the change of PU carrier as the NCO/OH ratio increased.…”

“…Figure 6 shows the viscosity of the sample 1 (carbonyl iron particle: 60 wt %) with the same weight concentrations of carbonyl iron particles under various magnetic fields. The phenomenon of the decreasing apparent viscosity with increasing shear rate is known as shear thinning behavior and is due to the presence of micrometer‐size particles 22. The constant value of viscosity increased with the increment of magnetic field when the shear rate is high.…”

“…The phenomenon of the decreasing apparent viscosity with increasing shear rate is known as shear thinning behavior and is due to the presence of micrometer-size particles. 22 The Figure 4 The viscosity of the samples for different reaction molar ratio in PU MRG. Figure 5 The viscosity of the samples for different molar mass of PPG in PU MRG.…”

Improved rheological properties of dimorphic magnetorheological gels based on flower-like carbonyl iron particles

“…It can also be seen from this figure that the viscosities of the MRG samples mainly increased with the increment of the flower-like CIPs weight ratio. It is known that, as the addition of particles, the increase in viscosity of the polymer systems is caused by the energy dissipation which occurs in the thin liquid film between neighboring particles as they move past each other [30]. The roughened surface of the flower-like particles increases the dissipation energy of the MRGs, which results in an increased viscosity in the MRG samples.…”