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Data evaluation in light scattering from solutions of branched polyethylene
Author(s) -
Helmstedt Martin,
Stejskal Jaroslav,
Burchard Walther
Publication year - 2000
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/1521-3900(200012)162:1<63::aid-masy63>3.0.co;2-z
Subject(s) - radius of gyration , exponent , polyethylene , solvent , gyration , dissolution , materials science , light scattering , thermodynamics , scattering , polymer chemistry , tetralin , chemistry , polymer , organic chemistry , physics , mathematics , optics , philosophy , linguistics , geometry
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 a 2 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.