Bead Size and Rheological Properties of SEBS-Based Elastic Beads

Styrene-ethylene-butylene-styrene, (SEBS), is a thermoplastic elastomer that has applications in robotics and shock absorption. While SEBS as a bulk material as well as an additive to solid composites has been extensively studied, this work focuses on developing SEBS-based beads to enhance material, particularly fluid, elasticity; the first time this has been seen in literature. SEBS bead mixtures were developed by mixing SEBS elastomer, water, and surfactant (Triton X-100) at high temperature. Stability, rheology, and microscopy of SEBS bead mixtures were studied as a function of neat SEBS concentration in SEBS elastomer, SEBS elastomer concentration, and surfactant concentration. Resulting bead mixtures were classified as creamed, homogenous and stable, or aggregated bead mixtures based on the mixture's tendency to separate into layers and ability to disperse in excess water. Microscopic studies suggest that while bead mixtures exhibit size polydispersity, the average bead size is a strong function of neat SEBS, SEBS elastomer, and surfactant concentrations. Rheological studies suggest that all the bead mixtures exhibit shear thinning behavior, and the overall viscosity of a given bead mixture is a function of both SEBS elastomer and surfactant concentration. The developed SEBS elastic beads can be used as additives to enhance the viscoelastic properties of fluid-based systems like magnetorheological and damping fluids.