Microwave moulding of expandable polystyrene foam with recycled material

Expandable Polystyrene (EPS) foam is used as a cushioning material for protective packaging of equipment and products to absorb the shock and to prevent the products from being damaged. The EPS foams must possess good compressive strength and cushioning property as indicated by their shock cushion curves which show the peak acceleration that will be transmitted by the foam of various thickness for different values of static stress. These curves are obtained by dropping a known weight onto various test samples of the cushioning material, and measuring the maximum acceleration transmitted. Traditionally, EPS foams are manufactured using the steam injection-moulding technique. EPS foams are not bio-degradable, and there have been some efforts made to recycle EPS material in the conventional steam process. Because cushioning properties of EPS foams with recycled materials are not known, they have not been used in protective packaging. These properties are being studied in this investigation. Earlier investigations by the researchers have shown that it is possible to produce EPS foams using microwave energy through rotational moulding to obtain uniform fusion. The compressive strengths of these mouldings were measured and found to be similar to those tested using the conventional steam process. It was found that addition of recycled EPS material reduced the compressive strength of the foam. However, the compressive strength is still within that accepted in the industry. The shock cushion curves of the foam were also affected. The minimum peak acceleration transmitted by the foams with recycled material are lower than those without.