Mechanical Properties of Iron Powder-Reinforced Polyurea Elastomer

This study investigated the enhancement of the mechanical and acoustic properties of polyurea (PU) composites by incorporating iron microparticles (Fe). The Fe/PU composites were prepared using a mixing process, where iron microparticles were evenly distributed within the polyurea matrix via mechanical stirring. The primary purpose of this study was to explore how varying volumes of iron microparticles influence the viscoelastic properties and acoustic performance of the composites, with a particular focus on applications in underwater acoustic stealth technology. Dynamic mechanical analysis was conducted to study the effect of the iron powder volume fraction on the mechanical properties of the composites, i.e., on the temperature-dependent storage moduli (E′), loss moduli (E″) and loss factor (tanδ). The intrinsic properties of the components and the nature of the interface between the phases determined the dynamic mechanical properties of the composite. It was found that the storage and loss moduli of the composite both increased as the iron volume fraction increased, which indicates that the incorporation of iron powder in a polyurea matrix appreciably induces reinforcing effects. Moreover, the tanδ curve of the Fe/PU composite generally had broader widths of the tanδ peak than those of pure polyurea, which showed better damping behavior. The height of the damping peaks depended on the iron powder content, and the glass transition temperature (measured as the temperature at the maximum value of the tanδ) shifted toward higher temperatures as the iron volume fraction increased. Also, the compression stress–strain curves of the composites obtained by a universal testing machine indicated that the addition of iron powder improved the compressive strength and the energy storage capacity of the composite. In addition, the acoustic absorption coefficient was found to increase with the addition of iron powder, and the increase in sample thickness was found to be the effective in improving low-frequency sound absorption.