Reducing Material Costs with Microcellular/Fine-celled Foaming

Abstract

Over the past few years, the steady increase in the cost of oil has resulted in higher resin prices. This market trend has imposed a significant burden on plastic parts manufacturers since resin typically accounts for 50—60% of the total manufacturing cost of plastics. In turn, many companies have been looking for ways to reduce the amount of resin they employ in order to compensate for their losses. In this study, high-density foaming experiments using polyethylene (HDPE) and polypropylene (PP) are carried out, demonstrating the extent to which these foaming processes represent breakthrough alternatives for plastics producers. N2 and talc are used as a blowing agent and as a nucleating agent, respectively. Two different pressure-drop rates are applied to study the effects of pressure-drop rates on HDPE and PP foams. It has been found that the cell density is the governing factor that determines the void fraction: the higher the cell density, the higher the void fraction. The authors successfully produced plastic foams that exhibited void fractions of up to 50% for HDPE and 40% for PP; these void fractions accounted for 40—50% reduction in material cost.