Data evaluation in light scattering from solutions of branched polyethylene

The molecular dimensions of branched polyethylene published in the literature were re‐evaluated to obtain the radii of gyration R_G and other relevant topological parameters. By means of the exponent a_s in the relationships R_G = b · M_s^a the reliability of the data and reasons for deviations were discussed. Linear and branched polyethylenes are molecularly dissolved only in the good solvent, tetralin, whereas in 1‐chloronaphthalene and 1,2,4‐trichlorobenzene the exponent a₂ is lower than expected for good solvents. Microgels and aggregates affect the exponents. After correction of the data by a two component separation method in combination with model calculations and the analysis of scattering curves, a consistent picture is obtained. This procedure is demontrated with fractions of branched polyethylene in the theta solvent diphenylmethane, which are indicating incomplete molecular dissolution.