Structure Formation as a Method of Forming Physicomechanical Characteristics of Films Obtained from Aqueous Solutions of Certain Polysaccharides

Abstract

The aqueous solutions of chitosan, succinyl chitosan sodium salt, and carboxymethylcellulose sodium salt are studied by the rheological method. An increase in the polymer concentration in solution leads to a sharp increase in viscosity due to formation of the entanglement network, the transition of the polymer solution to the gel-like state, a sharp increase in the relaxation time, and the appearance of elasticity of solutions. These systems are characterized by time anomalies characterized by a hysteresis loop, the area of which depends not only on concentration but also on the rate of increase/decrease of the shear rate. Thixotropy is observed in the intermediate concentration range, where supramolecular structures are formed and the time required for their destruction is comparable to the time of the experiment. This makes it possible to regulate a number of properties of materials formed from solutions. According to DSC studies, the glass transition temperatures and the melting temperatures of films obtained from solutions of different concentrations are different. The tensile stress and the elastic modulus of film polymeric materials pass through a maximum corresponding to the polymer concentration at which the maximum degree of structuring is implemented while maintaining the fluidity.