Abstract
This study involved preparation of hybrid polymer systems based on chitosan-poly(vinyl alcohol) (PVA) blends and modified Montmorillonite. These structures were characterized through microscopy and infrared spectroscopy; swelling measurements were performed to explore polymer absorbency. The behavior of polymer systems was studied through steady and oscillatory shear rheology. Results showed that more stable blend membranes were formed due to the strong interaction between chitosan and PVA. The membranes exhibited appreciable water uptake and were sensitive to saline solution with a slight shrinking.Shear viscosity was described by Cross model to characterize non-Newtonian behavior of all polymer solutions, the shear thinning increases with PVA content, while viscosity increases with chitosan extent. In oscillatory experiments, it was observed that all measured viscoelastic properties were influenced by blends composition and clay content. For all samples, results show a typical behavior of an entangled system in the case of semi-dilute macromolecular viscoelastic fluids. The dynamic moduli exhibited higher values for blends, compared with values of neat polymers, which are an indication of a good stability and a tendency of gel formation. Therefore, the prepared chitosan-PVA systems, which exhibited high swelling degrees and suitable viscoelastic properties, have promising applications in tissue engineering and membrane processes.
Highlights
Biopolymer membranes offer excellent biocompatibility and degradability; because of the significant sensitivity to water, their mechanical properties after swelling are poor
The polymer membranes prepared at different percentages of chitosan were studied by scanning electron microscopy (SEM)
The macromolecular chains are mainly entangled in the polymer network; after mixing, poly(vinyl alcohol) (PVA) and chitosan develop physical and chemical bonds that are responsible of these droplet effects
Summary
Biopolymer membranes offer excellent biocompatibility and degradability; because of the significant sensitivity to water, their mechanical properties after swelling are poor. Blends of chitosan and poly(vinyl alcohol) (PVA) have been reported to provide suitable mechanical properties for drug release control [5], food packaging films [6] and liquid mixtures separation [7, 8]. These valuable properties are due to inter-molecular interactions between the blended polymers chains. Most of the blend hydrogels are brittle and do not show high viscoelastic performance and thermal stability To overcome these intrinsic weaknesses, polymer based nanocomposites have been developed by dispersing fine ratio clay particles in the polymeric matrix [9]. Rheological properties of polymer solutions need to be controlled in order to initiate steady and dynamic flow in favorable conditions
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