Shape memory foam produced by an aqueous emulsifying technique

Abstract

Shape memory polymeric foam able to change from its secondary shape (memorized by polymer) back to its original shape when it is applied by external stimulus. Fabrication technique decides the morphology and properties of the foam and this process is strongly affected by type of blowing agent and foaming and curing temperatures. In this research, shape memory epoxy foam was produced by using aqueous emulsifying technique. In which, epoxy was dispersed in distilled water to form an epoxy-in-water emulsion system. Further curing was to set the epoxy into solid and to allow the evaporation of water; so the final epoxy foam was obtained. Two study effects were carried out in this research, which are effect of epoxy/water ratio and effect of blowing agent content on the physical properties, mechanical properties and shape memory property of epoxy foam. The sample was prepared by mixing epoxy and polyamide with water and ammonium bicarbonate by using mechanical stirrer in high emulsifying speed. After curing, the properties of epoxy foam were investigated by SEM, density, compression test, compression set and shape memory property test. It was found that morphology of epoxy foam was varied with the epoxy/water ratio. As the water level increase, the epoxy foam contained higher porosity and exhibited lower compressive load, modulus and compressive strength at 50% strain. Besides, higher water ratio also led in lower shape memory property. The blowing agent content was varied from 0, 5, 10, 15, and 20phr. The significant effect of blowing agent can be observed from the morphology of epoxy foam. BA0 performed different morphology compared to other formulations. Besides, epoxy foam with 15 phr ammonium bicarbonate has lowest porosity and performed high compression modulus and strength. BA 20 performed best shape memory property because it abled to remain its retained shape after 24 hours removing the load.