Berlin 2008 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 25: Polyelectrolytes
CPP 25.3: Vortrag
Mittwoch, 27. Februar 2008, 15:00–15:15, C 230
Small-angle x-ray scattering studies on lignosulfonate, a complex polyelectrolyte — •Ulla Vainio1,3, Rolf Andreas Lauten2, and Ritva Serimaa3 — 1HASYLAB at DESY, Notkestr. 85, D-22603 Hamburg, Germany — 2Borregaard Lignotech, P.O. Box 162, NO-1701 Sarpsborg, Norway — 3Department of Physical Sciences, P.O.Box 64, FI-00014 University of Helsinki, Finland
Lignosulfonate is a colloidal polyelectrolyte produced during sulfite pulping process of plants. Plant cell walls consist mostly of cellulose, hemicelluloses and lignin. During pulping lignin is made soluble and removed from the cell walls as lignosulfonate. Various uses have been invented for this byproduct of the pulping process, but even more could be possible once the behaviour of lignosulfonate in solution can be correlated to its structure.
Lignosulfonate particles of mass weighted molar mass 18 000 g/mol were studied in water and salt solutions using small-angle x-ray scattering and rheology. The concentration of the polyelectrolyte was varied from semidilute to concentrated.
Combined with molecular mass distribution obtained from gel permeation chromatography the model shape of an average lignosulfonate particles was discovered to be a flat ellipsoid by fitting different models to SAXS data. At water solutions below 0.1 mass fraction positions of the correlation peak observed in SAXS patterns scaled with concentration of lignosulfonate through a scaling law with exponent 0.28. Selfassociation of lignosulfonate particles was observed at higher concentrations from the SAXS data.