Solubility And Diffusivity Of Carbon Dioxide In Solid-state Polypropylene Composites

Gravimetric method has been adopted to measure solubility and diffusivity of CO2 in pure polypropylene (PP), PP/talcum (talc) composites and PP/active carbon (AC) composites at temperatures 343.15K,373.15K and 393.15K respectively and pressure range of 0-16MPa. The effect of different fillers and the interface between polymer and fillers have been investigated and analysised. Crystallinity of these materials dissolved by CO2 was calculated by DSC curves and solubility of CO2 in unit mass of amorphous region was deduced. Compared with the solubility of CO2 in pure PP, it is larger at lower pressure in PP/talc composites without interface modification but smaller at higher pressure. Solubility of CO2 in interface modified PP/talc composites is less than that in pure PP and PP/talc composites without interface modification. Diffusion coefficient of CO2 in PP/talc composites decreases as the talcum content increases. Solubility of CO2 in PP/AC composites increases as the active carbon content increases, and the solubility in PP/AC composites without interface modification is more than that in interface modified PP/AC composites. Diffusion coefficient of CO2 in PP/AC composites, which also increases with the increasing of active carbon content, is higher than that in pure PP. Solubility of CO2 in amorphous region of pure PP and interface modified PP composites were correlated with the Sanchez-Lacombe state equation in conjunction with the interaction parameters. The swelling degree of polymer matrix by CO2 was also predicted, which could prove the filler hinderance to the movement of polymer chains.