Development and characterization of magnetorheological elastomers

Abstract

A new class of materials termed magnetorheological elastomers (MREs) are developed that respond to externally imposed magnetic fields. Magnetic particles are embedded in viscoelastic solids or liquid elastomeric precursors. This kind of composite demonstrates a unique combination of good magnetic controllability and elastic properties. Polybutadiene (hydrocarbon based) based polyurethane MREs are developed because of their thermooxidative, hydrolytic, and chemical resistance. The structure-property relationships of polyurethaneMREs are investigated using several characterization techniques. Morphological features such as interdomains of soft and hard segments are identified with tappingmode atomic force microscopy. The thermal and mechanical behavior is evaluated with dynamic mechanical analysis, differential scanning calorimetry, and stressstrain tests.

Estimation of Mucus Clearance in Pulmonary Airways by Means of a Regression Model

“…There are several studies in the literature for coughing experiments. In some studies, to simulate pulmonary airway, a tygon tube [7], a rigid channel [8], or an endotracheal tube [3][4][5][6][7][8][9] were used. Airflow limitation is due to excess mucus and the effectiveness of the mucociliary clearance depends on rheology and the quantity of mucus as well as activity of the cilia indicated by King [11].…”

“…Airflow limitation is due to excess mucus and the effectiveness of the mucociliary clearance depends on rheology and the quantity of mucus as well as activity of the cilia indicated by King [11]. Mucus simulants were prepared by cross-linking locust bean gum with sodium tetra borate, 12% to simulate more gel-like mucus with a low V/E (viscosity/elasticity) ratio [1][2][3][4][5]. Aliquots of 3% simulant resemble to normal lung mucus and the stimulant obtained by mixing a higher amount of sodium tetra-borax correlate with diseases such as cystic fibrosis, chronic bronchitis, and asthma [12].…”

“…Aliquots of 3% simulant resemble to normal lung mucus and the stimulant obtained by mixing a higher amount of sodium tetra-borax correlate with diseases such as cystic fibrosis, chronic bronchitis, and asthma [12]. Mucus clearance was investigated mechanically and experimentally (in vitro) for different air velocities, coughing angles and surfaces using different simulants in references before [3][4][5][6][7][8][9]. Other references will be explained in the text as appropriate.…”

“…In this study, we have performed a multivariate regression analysis on the data set obtained from the tracheal model [4][5][6][7][8][9][10] where air flow was controlled by a 3-way solenoid valve between a constant pressure source and the test section, and the duration of flow was 0.2-0.3 seconds. Two different mixtures were used as mucus simulant (MS).…”

Creep and recovery behaviors of magnetorheological elastomers

“…Three components, the matrix, particles, and additives, are used in the sample of MRE. Both anistropic and isotropic MREs were fabricated and tested by a number of groups [5][6][7][8][9][10][11].…”