Caracterização de quitosana em ácido pirolenhoso destilado com potencial uso como coberturas protetoras

Abstract

Chitosan acid films can be used as coatings for vegetal tissues due to their antifungal and antimicrobial properties and, also, can act as an antiperspirant.Chitosan in pyroligneous distilled acid had been characterized comparatively to systems of this polymer in acetic acid 2 % (v/v). It was evaluated pH, conductivity, thermal behavior, molecular weight, gyration radio and second virial coefficient and rheological behavior. Auto supported films, obtained from chitosan in acetic acid, were evaluated with respect to the protection against the ultraviolet/visible radiation, resistance to water immersion, swelling degree and thermal degradation. The pyroligneous distilled acid is better solvent for this polymer comparatively to acetic acid solution. Chitosan, in both solvents, presented Newtonian behavior in the range of temperature from 10 to 40 °C at studied range of concentration and the system is thermally stable in the range of temperature from -40 to 60 °C. Films increased around 400 % of their weight, when immersed in water, being stable up to than seven days. Although a small loss of water under heating occurred, films are thermally stable up to 300 °C. The films block radiation efficiently UV-C (279-200 nm) and part of UV-B (319-280 nm), being able to be used as photo protectors. The molar absorptivity diminishes exponentially with the increasing of wavelength, these results show it is possible to obtain coating with different thicknesses to produce the desired protection against UV radiation. The films of chitosan in pyroligneous distillate acid will not be discussed in this paper.