Extrusion of a chemically foamed thermoplastic elastomer

A study was conducted to investigate the extrusion foaming of a thermoplastic elastomer (TPE) using a chemical foaming agent. The thermoplastic elastomer used was a polyethylene-co-octene and the blowing agent was an activated azodicarbonamide.; The experimental study focused on the establishment of the processing parameters to produce foams in the density range of 0.4--0.5 gr/cc. Effect of temperature, head pressure, and blowing agent level on foam density and morphology was verified. Dies with different aspect ratio (L/D) and entry angle were prepared and used to verify the effect of die geometry on pressure drop and foam properties. The results obtained are discussed in terms of similarities and differences between the foaming process of TPE and thermoplastics. Guidelines are also provided for TPE foaming on an industrial scale.