Measurement of N2 Solubility in Polypropylene and Ethene/Octene Copolymer

Determination of the solubility of a blowing agent, i.e. supercritical N₂, in polypropylene (PP) and elastomer material is crucial for achieving high-quality thermoplastic polyolefin (TPO) foams in automotive industry. A magnetic suspension balance (MSB) was employed in the experiments to measure the apparent solubility, while the swollen volume predicted by the Sanchez-Lacombe (SL) equation of state (EOS) was used to account for the buoyancy effect. The volume swelling of the polymer/gas mixture and the gas solubilities for both PP and polyolefin elastomer were discussed.