Measurement of solvent-independent polymer–polymer Flory–Huggins interaction parameters with the use of non-random partitioning solvents in inverse gas chromatography

Flory–Huggins interaction parameters of two well-known immiscible binary polyolefin blends consisted of high-density polyethylene (HDPE) and isotactic polypropylene (i-PP) and of HDPE and atactic polystyrene (a-PS) were measured by inverse gas chromatography (IGC). In particular, the data analysis approach recently proposed by the authors was used to test whether non-random partitioning solvents could be one of the causes for the solvent dependence problem commonly observed in IGC measurements. Current results reinforced our previous claim that the solvent dependence problem is mainly attributed to the use of the molar volumes of the solvents used in the experiment concurrently for the calculations of the solvent–stationary phase interaction parameters and not to the use of non-zero Δχ (Δχ=χ12−χ13) (i.e. non-random partitioning) solvents. In other words, solvent independent χ23 can be obtained so long as a single common reference volume is used for the data analysis. The interaction parameters for the HDPE/i-PP and HDPE/a-PS blends were found to be in the range of 0.03–0.10 and of 0.03–0.13, respectively. In the cases of 50/50 blends, the results were comparable to those obtained from neutron reflectivity measurements.