Propriedades viscosas e viscoelasticas de soluções e geis de quitosana

AUTOR(ES)
DATA DE PUBLICAÇÃO

2001

RESUMO

The chitosan biopolymer has recently being appointed as an important source of matrices used as adsorbents in processes for the recovery and purification of bioproducts, with new applications in areas such as biotechnology. An important advantage is that chitin occurs naturally and is commonly found in crustacean shells. The flexibility exhibited by these matrices became from the compatibility adsorbate/adsorbent and the possibility of structural modifications to satisfy diversified characteristics of chemical interaction and mechanical strength. In this work, the rheological characterization of chitosan solutions and gels was carried out in order to investigate viscosity and viscoelasticity properties. The concentrated solutions were prepared by dissolving chitosan with acid acetic solution and the gels were prepared by adding glutaraldehyde, solutions at different concentrations of 2,5g/100ml, 3,Og/100ml and 3,5g/100ml and temperatures of 10°C, 30°C and 50°C. The viscosity and viscoelasticity properties of chitosan samples were measured with a rheometer (model Haake CV20). The equipment can be operated in two different ways in order to obtain the experimental data. The first one is the steady shear rheological measurement, where the viscosity properties are described through values for shear stress, shear rate and shear viscosity. The second is the oscillatory shear rheological measurement, where the viscoelasticity properties are described through values for storage modulus, 1055 modulus and complex viscosity. The correlation between structure and properties exhibited by chitosan samples and gels modified by crosslinking with glutaraldehyde were studied. Rheological specific models were adjusted to the experimental data in order to describe the behavior of chitosan solutions and gels. The parameter determinations allow concluding that is possible to prepare and characterize chitosan samples as concentrated solutions and gels depending only on the concentration and the degree of crosslinking of the sample studied

ASSUNTO(S)

viscoelasticity viscosidade quitosana viscoelasticidade chitosan biopolimeros crosslinking biopolymers

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