Untersuchung zur Flockungsfähigkeit von Polyacrylamid-co-acrylaten (0 – 100 mol-% Acrylamid)

The flocculation activity of poly(acrylic acid), poly(acrylamide-co-sodium acrylates) and polyacrylamide, which were prepared in our laboratory, was investigated. The flocculation speed of polyacrylamide was found to increase with increasing molecular weight. The aqueous polyacrylamide solutions as well as the samples stored in the solid state showed, when M_η ≥ 1,5 · 10⁶ g/mol, a time-dependent decrease of the intrinsic viscosity and simultaneously a decrease of flocculation speed. This was accompanied by a diminution of the radius of gyration. These time-dependent facts were caused by a conformational change of the molecular structure and not by molecular degradation. Linear polyacrylamides were better flocculation agents than branched ones (20 branches) with the same total molecular weight. Poly(acrylamide-co-sodium acrylates) exhibited a maximum of flocculation activity at a comonomer degree of about 70 mol-% acrylate.