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2 Applied Mechanics and Engineering

2 1999

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A rheological constitutive equation for suspensions of microcrystalline cellulose

100%

Jakobsons E. , Faitelson L. , Laka M. , Chernyavska S.

1999

tom Vol. 4, no spec.

17-20

The steady and oscillatory shear flow behaviors were investigated for the suspension of 8 wt.% microcrystalline cellulose in water. The values of dynamic viscosity higher than those of effective viscosity at 'gama'='omega' are observed in the range of the used frequency and shear rate (0.063-50 s-1). Modified Akay-Leslie anisotropic liquid model is proposed for quantitative account of the test data.

Rheological peculiarities of microcrystalline cellulose gels

100%

Laka M. , Chernyavska S. , Faitelson L. , Jakobsons E.

1999

tom Vol. 4, no spec.

351-355

Rheological properties of MCC hydro- and alcogels have been studied. MCC gels were obtained by way of dispersing in water, ethyl alcohol and propyl alcohol media the wood pulp destructed to the levelling-off degree of polymerization (LODP) of cellulose by a method developed by us. At a sufficiently high cellulose concentration which was dependent on the liquid medium, MCC gels with rheological properties typical for liquid crystalline polymers (flow curves with three characteristic regions, viscosity concentrations curves with a local maximum, etc.) were obtained. These properties are more pronounced for hydrogels. MCC hydrogels are characterized also by a higher liquid phase retention volume (~ 380%), which is an important characteristic of a stable gel. For MCC alcogels, it makes up 40-65%. Inferior properties of MCC alcogels are connected with the chemical structure of alcohol molecules which, as compared to water molecules, are less favourable for bonds formation among cellulose microcrystallites and the liquid medium.