Preparation and Characterization of Chitosan/Agar Blends: Rheological and Thermal Studies

Abstract

In this work, a number of mixture aqueous solutions of chitosan/agar (CS/AG) at different ratios (considering chitosan as the main component) were prepared. The rheological properties i.e. shearing viscosity and shear stress of the blend solutions as a function of shear rate as well as the thermal properties of the blend films were investigated. Among the parameters studied were temperature, shearing time and storage time. Results showed that almost Newtonian behavior was observed at temperatures from 40 o C to 55 o C for the ratios 100/0, 90/10, 80/20 and 70/30. However, the proportions 60/40 and 50/50 showed a clear shear thinning behavior (pseudoplastic non-Newtonian behavior). It was also found that all the blend solutions obeyed the Arrhenius equation. In addition, the effect of shearing time on the shearing viscosity of all blends did not show any significant differences at all shearing times applied in this study except the proportion 50/50 wherein decreasing in shearing viscosity and shear stress was observed as the shearing time increased. Furthermore, different behaviors were observed for the blend solutions when the period of storage was extended to three weeks. The FTIR results and the differential scanning calorimetery (DSC) curves showed that the interaction between chitosan and agar can occur.

Facile preparation of agarose–chitosan hybrid materials and nanocomposite ionogels using an ionic liquid via dissolution, regeneration and sol–gel transition

“…[3][4][5] Since CH is a good interacting polymer having amine groups, it can combine or interact with an AG hydroxyl group to form an AG-CH complex, forming environmentally safe composite materials with combined advantages suitable for different applications. [6][7][8] However, the preparation of composites of these biopolymers in water or common organic solvents under mild conditions is not an easy process due to the presence of many hydroxyl groups, intra-and intermolecular hydrogen bonding and molecular close chain packing which creates difficulties in their effective solubilization. Besides solubility limitations, there are several other problems, such as solvent handling, volatility, generation of poisonous gases or waste and solvent recovery generally encountered while processing the biopolymers in common organic solvents.…”

Efecto del almacenamiento sobre las propiedades físicas de las películas de quitosano con inclusión de aceites esenciales de tomillo y romero

“…El efecto endotérmico se puede atribuir a la pérdida de peso por la evaporación del agua y de las trazas de disolvente [29]. La temperatura de cristalización más alta es causada por la inclusión de los aceites esenciales, así como al aumento de sus concentraciones [27].…”

Preparation of Chitosan Beads for the Adsorption of Reactive Blue 4 from Aqueous Solutions

“…This reduction could be due to the increased intermolecular entanglement of chitosan chains at higher chitosan concentration (>2 wt.%). Thus, the freedom of movement of the individual chains became restricted because of the increased extent of entanglement, which resulted in a significant change in the porous network and decrease in the number of available functional groups and consequently reduced adsorption capacity [13]. Thus, the dye removal gradually decreased with increasing chitosan concentration.…”