Processing of expandable polystyrene using microwave energy

Abstract

Expandable polystyrene (EPS) commonly known as styrofoam, is used widely in the packaging industry for the protection of goods. The styrofoam cushion is produced commercially by a steam injection process from pre-expanded EPS beads. This process, which requires the cyclic heating of the aluminum mould for expansion of the EPS and the subsequent cooling of the same mould before the ejection of the product, is highly inefficient in terms of energy utilization. In the presently reported investigation, microwave energy was used to process the EPS. Experimentation was carried out in three phases comprising: (a) pre-expansion of the EPS; (B) moulding using pre-expansion beads; and (c) direct moulding from EPS raw material, i.e. by-passing the pre-expansion stage. Various properties of the pre-expanded beads and of the moulded products produced under various settings of the process parameters were explored, including the determination of the compressive strength of the moulded product to assess its potential as a protective cushion. The results for the three phases have been evaluated and discusses, the conclusion from which is that microwave energy can offer a good alternative to steam in the processing of EPS.