Magnetic responsive materials can be used in a variety of applications. For structural applications, the ability to create tunable moduli from relatively soft materials with applied electromagnetic stimuli can be advantageous for lightweight protection. This presentation will discuss work involving ferromagnetic carbonyl iron particles (CIP) embedded into two different systems. The first material system is a model cementitious system of CIP and kaolinite clay dispersed in mineral oil. The magnetorheological behaviors were investigated using parallel plates with attached magnetic accessory to evaluate deformations up to 1 Tesla. Slurries were formulated to have a consistency similar to freshly mixed cement pastes with CIP loadings up to 50 wt. %. Magnetic small amplitude oscillatory time sweeps on the slurries indicated the CIP interactions were leading to a stiffening of the slurry signified by the increase in the storage modulus. The yield stress of these slurries was measured using rotational and oscillatory experiments and was found to be controllable based on CIP loading and magnetic field strength with yield stresses ranging from 10-10<sup>5</sup> Pa. The second material system utilizes a polystyrene-butadiene rubber solvent casted films with CIP embedded. The flexible matrix can be stiffened and become rigid when an external field is applied. Composite sample films were formulated with CIP up 5 wt. % to understand polymer-particle interactions on rheological and mechanical properties.

Magneto-rheology for tunable structural design

2019 Fall National Meeting

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