Single-Step Rotational Foam Molding of Skin-Surrounded Polyethylene Foams

Abstract

This paper demonstrates howthe rotational foam molding process can be employed for the manufacture of plastic articles that have a distinct layer of nonfoamed skin surrounding a foamed core or layer. It is focused on the singlestep processing principle, the main feature of which is the simultaneous introduction of both the foamable and nonfoamable resin into the cavity of the mold at the beginning of the cycle. Although this advanced concept eliminates the need for process interruptions and the use of drop boxes or plastic bags, it requires an appropriate processing strategy that would assure that the execution of the adhesion of the nonfoamable thermoplastic resin to the internal surface of the mold always takes place prior to the activation of the foamable resin.