Rotational Foam Molding of Metallocene Catalyzed Polyethylene: CBA Screening and Process Characteristics

The objective of this work is to investigate the effects of different chemical blowing agents (CBAs) and processing conditions on the cellular structure of foamed metallocene polyethylene and characterize an appropriate blowing agent. An experimental study was conducted to produce metallocene polyethylene foams in dry-blending-based rotational foam molding. The critical processing parameters that optimize the foam structure have been identified through modifications of the molding conditions. The physical properties and cellular structure of the final foamed parts were also examined. The foaming performance of exothermic and endothermic CBAs was studied. It was revealed that selecting a suitable CBA is crucial as the foam structure depends significantly on the properties of the blowing agent. Exothermic blowing agents resulted in greater foam density reduction and exhibited a wider processing window compared to endothermic blowing agents. It was found that a balance between different properties of the blowing agent is required to achieve control over the foam structure.