Untypical rheological behaviour of the lignite-carboxymethylcellulose-water dispersion system

Untypical rheological behaviour of the lignite-carboxymethylcellulose-water dispersion system

Peer-reviewed article not indexed in WoS or Scopus

CSuspensions of lignite in a solution of a high molecular weight carboxymethylcellulose show peculiar rheological behaviour. Unless the lignite concentration is sufficiently high apparent viscosity and viscoelastic moduli of the suspension are lower than those of the pure solution. This effect is not suppressed by changing pH and seems to be common for low concentrated suspensions in solutions of high molecular weight (bio)polymer. It is explained by specific structuring of suspensions. Lignite particles at lower concentration separate long cellulose chains and facilitate their movement under shear flow. The particles loosen inter-chain contacts, disturb and release elastic gel-like structure formed by the long cellulose chains, which results, in the low strain oscillatory deformation, in decrease of the moduli and in increase of the loss angle. If the amount of lignite particles is sufficiently high suspension stiffening occurs as usual. No such effect was observed for suspensions prepared from the low molecular weight derivative.

CSuspensions of lignite in a solution of a high molecular weight carboxymethylcellulose show peculiar rheological behaviour. Unless the lignite concentration is sufficiently high apparent viscosity and viscoelastic moduli of the suspension are lower than those of the pure solution. This effect is not suppressed by changing pH and seems to be common for low concentrated suspensions in solutions of high molecular weight (bio)polymer. It is explained by specific structuring of suspensions. Lignite particles at lower concentration separate long cellulose chains and facilitate their movement under shear flow. The particles loosen inter-chain contacts, disturb and release elastic gel-like structure formed by the long cellulose chains, which results, in the low strain oscillatory deformation, in decrease of the moduli and in increase of the loss angle. If the amount of lignite particles is sufficiently high suspension stiffening occurs as usual. No such effect was observed for suspensions prepared from the low molecular weight derivative.

carboxymethylcellulose, lignite, rheology

carboxymethylcellulose, lignite, rheology

KLIMOVIČ, M.; PEKAŘ, M.

01.01.2007

0303-402X

COLLOID AND POLYMER SCIENCE

285

8

Federal Republic of Germany

865

872

8

http://hdl.handle.net/