Sorption of olefins in high impact polypropylene - experimental determination and mass transport modeling

Gas solubilities as well as sorption rates are measured for ethylene and propylene in high impact polypropylene samples. As sorption rates are influenced by material properties and powder morphology, non-porous polymer films are analyzed for the determination of effective diffusion coefficients of the material. These sorption rates are afterwards adopted for modeling of powder sorption experiments. In that way, integral sorption lengths in the polymer powders are determined. Results reveal that subdomains in the order of 250–500 μm are the rate determining unit for mass transport. The size of the clusters can be described by a correlation to polymer yield; sorption rate of the material can be described as a function of crystallinity