Preparation and Characterization of Chitosan/Poly(Vinyl Alcohol) Blended Films: Mechanical, Thermal and Surface Investigations (original) (raw)
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P oly (vinyl alcohol)-chitosan blend films were prepared by casting the respective polymer solutions. The glutaraldehyde was used as a cross-linking agent. A series of PVA-chitosan blends were prepared by varying the ratio of the constituents. Mechanical and physical properties of blended films such as tensile properties in the dry and wet states, water uptake, surface tension and contact angle were characterized. Blending PVA and chitosan improved strength and flexibility of the films in the dry and wet states. Cross-linking with glutaraldehyde improves tensile strength and decreases elongation of the films. PVA Content in the blends increases water uptake while cross-linking the films with glutaraldehyde causes less hydrophilicity. Water uptake in PVA-chitosan blends can be controlled by variation of their contents, cross-linking agent and the pH of solution. Blending of PVA and chitosan improves bulk and surface hydrophilicity of blended films.
Mechanical, Thermal and Surface Investigations of Chitosan/Agar/PVA Ternary Blended Films
E-Journal of Chemistry, 2011
The mechanical and thermal properties of chitosan/agar/poly vinyl alcohol (CS/AG/PVA) ternary blended films having various proportions considering chitosan as the main component were investigated. The various variables static water contact angle such as contact angle, drop base area, drop volume and drop height was also studied in correlation with the variation of time. Results obtained from mechanical measurements showed a noticeable increase in the tensile strength (TS) coincided with a sharp decrease in elongation percent at break (E%) of blended films with increasing agar and PVA contents. The DSC results prevailed the development of an interaction between chitosan individual components: agar and PVA. Moreover, an enhancement of the wettability of the blends was obtained with increasing agar and PVA contents. It was also found that the pure CS film and the blended films with 90/05/05 and 80/10/10 compositions were more affected by time than blended films with other compositions when the contact angle, the drop height and the drop length were studied as a function of time. In addition, when the drop is initially placed on the substrate, the drop area and the drop volume of all films remained almost constant up to a certain time after which they showed a slight difference with the elapse of time.
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The present study deals with the preparation of polyvinyl alcohol (PVA)/chitosan (CS) blends with different compositions. The physico-chemical characterization and compatibility have been studied by means of polarized light optical microscopy, FT-IR spectroscopy, DSC, DMTA, TG/DTG and rheological measurements. The film-forming ability of the blends was confirmed by rheological tests, as they showed higher viscosity and improved viscoelastic properties in comparison with pure PVA. The obtained films were transparent and homogenous with enhanced mechanical properties and thermal stability.
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In the present study, we report the development of poly (vinyl alcohol) (PVA) and chitosan oligosaccharide (COS)-based novel blend films. The concentration of COS was varied between 2.5–10.0 wt% within the films. The inclusion of COS added a brown hue to the films. FTIR spectroscopy revealed that the extent of intermolecular hydrogen bonding was most prominent in the film that contained 5.0 wt% of COS. The diffractograms showed that COS altered the degree of crystallinity of the films in a composition-dependent manner. As evident from the thermal analysis, COS content profoundly impacted the evaporation of water molecules from the composite films. Stress relaxation studies demonstrated that the blend films exhibited more mechanical stability as compared to the control film. The impedance profiles indicated the capacitive-dominant behavior of the prepared films. Ciprofloxacin HCl-loaded films showed excellent antimicrobial activity against Escherichia coli and Bacillus cereus. The pr...
Miscibility and thermal stability of poly(vinyl alcohol)/chitosan mixtures
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The miscibility and the thermal behaviour of chitosan acetate (ChA) with poly(vinyl alcohol) (PVA) have been investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Chitosan is blended with poly(vinyl alcohol) in acetic acid solution and this solution is cast to prepare the blend film. From thermal curves the thermal transitions: T g , T m and characteristic temperatures of decomposition: T di , T max have been determined and compared. The influence of the degree of PVA hydrolysis on the thermal properties of blend systems has been discussed.
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Transparent films of chitosan (CH), carboxymethyl chitosan (CMCH), and their blends were prepared using water or acetic acid as solvent and glycerol as plasticizer. Scanning electron microscopy micrographs of crosssection of the films indicated a multilayer structure for CH film and a compact and continuous one for CMCH film. In both solvent systems, increasing of concentration of plasticizer resulted in decreasing of tensile strength (TS) and increasing of elongation at break (% e b) of CMCH films. Moreover, CMCH films exhibited water vapor and oxygen barrier properties in the range of the values accepted for food packaging films (0.59-0.89 9 10-14 kg/s m Pa and 0.8-3.1 9 10-3 ccO 2 /m day atm). Although the barrier properties of CMCH films were comparable with that of CH films, CH film had significantly higher TS and % e b. Blending of CMCH with CH (75 and 25 %, respectively) significantly enhanced the TS and % e b of the obtained film compared to CMCH films (2.1 and 1.7 times, respectively). The water vapor and oxygen permeabilities (1.25 9 10-14 kg/s m Pa and 3.4 9 10-3 ccO 2 /m day atm, respectively) were still comparable with films of CH and CMCH.
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The premise of this work is the modification of the properties of chitosan-based film for possible use in food packaging applications. The biofilm was prepared via thermal and mechanical treatment through blending polymers with chitosan using Polyvinyl Alcohol (PVA) and loading different types of chemical agents, i.e., citric acid (CA), succinic acid (SA), and tetraethoxysilane (TEOS). The modification was carried out under high-speed homogenization at elevated temperature to induce physical cross-linkage of chitosan polymer chains without a catalyst. The findings showed that PVA improved the chitosan films’ Tensile strength (TS) and elongation at break (Eb). The presence of chemicals caused an increase in the film strength for all samples prepared, in which a 5% w/w of chemical in the optimum composition CS/PVA (75/25) provided the maximum strength, namely, 33.9 MPa, 44.0 MPa, and 41.9 MPa, for CA-5, SA-5, and TEOS-5, respectively. The chemical agents also increased the water conta...
Preparation and Characterization of Chitosan/Polyvinyl Alcohol Blends-A Rheological Study
E Journal of Chemistry, 2010
Blends of chitosan (CS) and polyvinyl alcohol (PVA) of different proportions (considering chitosan as the main component) were prepared. The rheological properties of the obtained blend solutions such as the shearing viscosity and the shear stress were investigated as a function of shear rate under various temperatures, shearing times and solution storage times using a digital viscometer. The CS/PVA solutions showed a Newtonian behavior at temperatures in the range of 40-55 o C regardless of the blend composition. This was accompanied by a general decrease in the viscosity with increasing PVA content in the blend. The heatdependant viscosity changes of the blend solutions were found to follow Arrhenius equation. The shearing time was found to have no significant effect on the shearing viscosity of all blended solutions. However, the variation of solution storage period was found to have a mixed effect when time was extended to 3 weeks.
Rheological and morphological studies of chitosan/agar/ poly (vinyl alcohol) blends
2010
In this study, a number of ternary mixture aqueous solutions of chitosan/agar/poly vinyl alcohol (CS/AG/PVA) at different proportions (considering chitosan as the main component) were prepared. The effects of temperature, shear rate, shearing time and storage time on the rheological properties, i.e., the apparent viscosity and the shear stress as a function of shear rate were investigated for the ternary system. Results showed that a Newtonian behavior was observed at temperatures from 40 C to 55 C for the ratios o o 90/05/05 and 80/10/10. The mixture solutions become pseudoplastic (shear thinning) when the concentrations of agar and PVA were higher than 10 % each. It was also found that all the blend solutions obeyed the Arrhenius equation. In addition, the effect of the shearing time on the shearing viscosity did not show any significant change at all shearing times applied for lower concentrations than 15% of each of agar and PVA in this study. However, at higher concentrations of agar and PVA, a rheopectic behavior was observed. Furthermore, different behaviors were observed for the blend solutions when the period of storage was extended to three weeks. The observations obtained from the rheological measurement suggested the existence of interaction between the three polymers. Finally, the morphology of the blended films confirmed the interaction between the functional groups of the blend components.
Surface studies of microcrystalline chitosan/poly(vinyl alcohol) mixtures
Applied Surface Science, 2012
In the present study, the surface properties of microcrystalline chitosan (MCCh), poly(vinyl alcohol) (PVA) and MCCh/PVA blends (made from acetic acid solutions with the MCCh concentration ranging from 20% to 80%) have been studied by the tapping-mode atomic force microscopy (AFM), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The changes of topography images are considered by determining the root mean square (RMS, R q ) deviation in the image data. For PVA samples, the transition between adjacent lamellae occurs through holes, islands, and bicontinuous structures. The AFM images showed also the lamellar structure of PVA in the blend. The crystalline topography of MCCh/PVA film surface suggests the presence of PVA on the top surface. The FTIR spectra of film blends, in the amide I and II region of MCCh and the hydroxyl stretching bands of PVA have been analyzed. FTIR analysis showed the existence of a weak interaction of the hydroxyl or amino groups of microcrystalline chitosan with hydroxyl groups of PVA.