Microcellular structure development with microspheres in rotational molding

The use of microspheres for producing a microcellular foam structure is a new development in rotational molding. Microspheres are commercially available in the form of small hollow glass beads as well as heat expandable polymer microspheres. This work investigates the effects of resin properties and processing conditions on foamed rotationally molded parts containing rigid glass beads and expandable polymer microspheres. Parts were produced using a metallocene PE, EVA, metallocene PP and conventional PP resin. The mechanical and physical properties of these parts have been examined - including surface finish, density, cell distribution, stiffness and elongation at break.