Preparation and characterization of isotropic polyurethane magnetorheological elastomer through in situ polymerization

Abstract

ABSTRACT:The highly filled isotropic polyurethane (PU) elastomer with a magnetorheological (MR) effect was prepared through an in situ polycondensation method. The carbonyl iron particles were treated by coupling agents and then the dispersions of polyol/carbonyl iron particles was prepared by a ball milling process. The dispersion problem of magnetizable particles at a high content in PU matrix was tried to overcome by the combination of surface modification, ball milling, and in situ polymerization. The microstructure and properties of the composite were examined in detail. With increasing the content of carbonyl iron particles, the degree of phase separation of PU increased and the glass transition temperature (T g ) of PU soft segment decreased. Highly filled carbonyl iron particles led to the decrease in the thermal stability of PU matrix, especially in the heating air atmosphere. The MR effect appeared when the content of carbonyl iron particles was higher than 50 wt %, and became relatively pronounced at a 70 wt % of carbonyl iron content. The mechanical properties of PU MR elastomers were deteriorated significantly at a high content of carbonyl iron. Surface modification of carbonyl iron particles can improve the mechanical properties to some extent; however, it was also found that surface modification led to a decrease in the MR effect because of the improved interfacial adhesion. The MR test showed that the maximum absolute MR effect and relative MR effect of PU composite were $ 0.31 MPa and $ 8.1% at 1 Hz and 400 mT with 70 wt % of carbonyl iron, respectively.

Fatigue life prediction of magnetorheological elastomers subjected to dynamic equi-biaxial cyclic loading

“…A magnetorheological elastomer (MRE) is a composite material that comprises an elastomeric matrix and magnetic particles. The matrix of MREs can be soft materials, such as silicone rubber [2,3], relatively harder materials, such as natural rubber [4], or elastomers with easily adjustable properties, such as polyurethane [5,6].…”

Physicochemical Properties and Stress-Strain Compression Behaviors of a Waste based Magnetorheological Elastomers

“…Thermal analyses such as Di erential Scanning Calorimetry (DSC), thermogravimetric analysis (TGA/DTA), Dynamic Mechanical-Thermal Analysis (DMTA), aging test, thermal oxidation, and UV oxidation are usually conducted to investigate the performance of the elastomeric materials including MREs as their response to thermal loads. The studies on thermal ans of the MREs based on virgin rubber and/or saturated elastomers can be found in some previous works [27,41,57,[79][80][81][82]. However, since the specimens studied in this report are made of waste rubber as the MREs matrix, there is no report that precisely explains their stability and degradation.…”

“…Meanwhile, the unsaturated elastomers are less interesting since they need longer fabrication processes and more various devices involved. To date, the utilized unsaturated elastomers have been natural rubber [39][40][41] and synthetic rubber, i.e. styrene butadiene rubber [42], chloroprene rubber (CIIR) [43], Bromo butyl rubber (BIIR) [44], isobutylene-isoprene [39], cispolyisoprene [45], cis-polybutadiene [27,[46][47][48][49][50], acrylonitrile rubber [51][52][53][54], and ethylene-propylene rubber [53,54].…”

Mechanical Properties of Magneto‐Sensitive Elastomers in a Homogeneous Magnetic Field: Theory and Experiment

“…Another important topic is the influence of the magnetic field on the mechanical moduli of MSEs. Many experimental works studied the dependence of the static mechanical moduli of MSE on the magnitude of external magnetic field . The experimental works show that the static shear moduli of MSEs increase with increasing strength of the magnetic field and depend on the microstructure of these materials, e.g., on the volume fraction and spatial distribution of magnetic particles …”