Reducing Material Costs with Microcellular/Fine-celled Foaming

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.

[1]  Chul B. Park,et al.  Use of Nitrogen as a Blowing Agent for the Production of Fine-Celled High-Density Polyethylene Foams† , 2006 .

[2]  Chul B. Park,et al.  Challenge to Extrusion of Low-Density Microcellular Polycarbonate Foams Using Supercritical Carbon Dioxide , 2005 .

[3]  Gregory L. Branch,et al.  Extrusion of Microcellular Foams Using Pre-Saturated Pellets and Solid-State Nucleation , 2004 .

[4]  Chul B. Park,et al.  Fundamental foaming mechanisms governing the volume expansion of extruded polypropylene foams , 2004 .

[5]  Chul B. Park,et al.  Effects of die geometry on cell nucleation of PS foams blown with CO2 , 2003 .

[6]  R. Gendron,et al.  Continuous extrusion of microcellular polycarbonate , 2003 .

[7]  Chul B. Park,et al.  Study of Shear and Extensional Viscosities of Biodegradable PBS/CO2 Solutions , 2001 .

[8]  Jingyi Xu,et al.  Microcellular foam processing in reciprocating-screw injection molding machines , 2001 .

[9]  M. Liang,et al.  Production of Engineering Plastics Foams by Supercritical CO2 , 2000 .

[10]  Chul B. Park,et al.  Challenge to fortyfold expansion of biodegradable polyester foams by using carbon dioxide as a blowing agent , 2000 .

[11]  R. D. Venter,et al.  Low density microcellular foam processing in extrusion using CO2 , 1998 .

[12]  R. D. Venter,et al.  Challenge to the production of low-density, fine-cell HDPE foams using CO2 , 1998 .

[13]  Chul B. Park,et al.  The effect of talc on cell nucleation in extrusion foam processing of polypropylene with CO2 and isopentane , 1998 .

[14]  Chul B. Park,et al.  A study of cell nucleation in the extrusion of polypropylene foams , 1997 .

[15]  R. D. Venter,et al.  Extrusion of polypropylene foams with hydrocerol and isopentane , 1996 .

[16]  Chul B. Park,et al.  Effect of the pressure drop rate on cell nucleation in continuous processing of microcellular polymers , 1995 .

[17]  Shau‐Tarng Lee,et al.  Shear effects on thermoplastic foam nucleation , 1993 .

[18]  J. Martini,et al.  The Production and Analysis of Microcellular Thermoplastic Foam , 1982 .