Extrusion compounding of polyethylene with blowing agent

Abstract

Cellular plastics are very attractive for the production of lightweight, structural and/or large dimension parts, e.g., boats, floaters, decks, etc. For their production, polymers and chemical blowing agents are either mixed or compounded prior to processing by injection or rotational moulding. It is essential to ensure good dispersion of the blowing agent in the polymeric matrix, and prevent its activation from occurring during compounding, i.e., an optimal processing window must be used. The aim of this work is to produce medium density polyethylene with Azodicarbonamide (MDPE/ADCA) masterbatches in pellet form for further processing by rotational moulding. For that purpose, a set of experimental procedures was conducted to evaluate the correct processing window without premature expansion during extrusion. Upon melt compounding of the masterbatch in pellets of different sizes, foamed parts were produced and characterized in terms of visual aspect, expansion ability and morphology.