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Blends of poly(ε-caprolactone) (PCL) with chitosan and a whey-protein-isolate (WPI) were prepared by solution mixing and film casting. The purpose was to increase the water vapour resistivity of chitosan and whey by blending them with a hydrophobic biodegradable polymer. The water vapour transmission rate was determined by a standard technique and by a new technique based on microcalorimetry. The...
The use of infrared spectroscopy for characterization of the composition of chitin and chitosan covering the entire range of degree of acetylation (DA) and a wide variety of raw materials is examined further. The ratio of absorbance bands selected was calibrated using 1 H liquid and 13 C CP-MAS solid-state NMR as absolute techniques. IR spectra of the structural units of these...
There are a few communications concerning the relaxation temperature corresponding to the glass transition temperature of chitosan. We succeeded in observing the T g of chitosan (to be ca. 203 o C) by the direct and careful measurement of differential scanning calorimetry (DSC), which had been assumed not to be sensitive enough to detect it. In addition to this observation, the dynamic...
The thermal degradation properties of chitosan and lactic and/or glycolic acid grafted chitosan have been studied by differential scanning calorimetry (DSC) and thermogravimetric analyses (TG) in the range of 25–500°C. Both DSC and dynamic TG results show that the samples are thermal degraded easily after grafting the lactic and/or glycolic acid. From the isothermal TG experiments, the initial activation...
Physically crosslinked chitosan hydrogels were synthesized by grafting d,l-lactic acid (LA) and/or glycolic acid (GA) with different feed ratios. The physical crosslinking was formed due to the hydrophobic side chains aggregation and intermolecular interactions through hydrogen bonds between side and main chains. The crystallinity of original chitosan decreased by grafting LA and GA. The structural...
Hydrogels were prepared from blends of poly(vinyl alcohol) (PVA) and chitosan in varying proportions. Electron spectroscopy analysis of the resulting hydrogel membranes, cast on glass plates, revealed that the chitosan component was concentrated on the surface of the air-surface side of the membranes and was nearly constant from 10 to 40wt% of chitosan content of the blends. The increasing water-contact...
Chitin was extracted from squid pens and the used conditions allow to obtain a completely N-acetylated β-chitin with a molecular weight large enough for the obtention of chitosans of high molecular weight. Deacetylation, leading to the obtention of chitosan, was performed according to two processes (Kurita and Broussignac conditions) and the physicochemical characteristics (degree of acetylation and...
The interpolyelectrolyte reaction between chitosan hydrochloride (CHI) and sodium polygalacturonate (NaPGA) has been investigated by conductimetric measurements. The composition of the reaction mixture, Z, was assessed by monitoring the conductivity when a CHI solution was added to a solution of NaPGA. It was determined to be unity at the equivalence point, indicating a 1:1 stoichiometry for the complex...
Recently we reported on chitosan hydrogel systems having excellent laser damage resistance. The measured laser damage threshold (LDT) was better than BK7 glass and quartz, commonly used inorganic optical materials, and 20 to 35 times higher than commercial PMMA, a popular polymer optical material. In this study, we continue our investigation of the phase transition behavior of water within the hydrogels...
Macromolecular interpolymer complexes were prepared by blending concentrated equimolar solutions of chitosan and poly(4-N-methacrylamidobenzoic acid) and evaporation of the solvents. The products obtained presented the structure of interpolymer complexes as indicated by FTIR spectroscopy. The thermal treatment of the solid products at 120 o C gives rise to a partial dehydration together...
Formation of Schiff's base between 2-O-(formylmethyl)-β-cyclodextrin and chitosan with an average molecular weight of 40 000 in acetate buffer at pH 4.4, followed by reduction with sodium cyanoborohydride produced a β-cyclodextrin-linked chitosan in a one-pot reaction. The product, which had a degree of substitution of 37%, was soluble in water at neutral and alkaline conditions. UV-visible and circular...
Chitosan (deacetylated chitin), which is a naturally occurring polysaccharide having primary amino groups, is known to be insoluble in water because of its strong intermolecular hydrogen bonds. We prepared water-soluble poly(ethylene glycol) grafted chitosan (PEG-g-chitosan) through the chemical modification of chitosan and investigated its aggregation phenomenon in aqueous solutions. The solution...
Chitosan functionalized with 2-pyridinecarboxaldehyde and 4-pyridinecarboxaldehyde were used to study the equilibrium constants of adsorption copper(II) in aqueous solutions. The degree of substitution of NH 2 groups of the chitosan was 0.85. The adsorption parameters K (adsorption constants Langmuir) and R T (maximum value of adsorbed copper(II) ions) were calculated using Langmuir's...
The gelation of the biopolymer chitosan in solution through crosslinking reactions with Pt(ii) has been investigated by simultaneously monitoring both the viscosity of the system and the number of metal-amine bonds formed per chitosan chain, as probed spectroscopically. The variables studied in the investigations included the chitosan to Pt(ii) concentration ratio, the pH of the reaction solution,...
One method of synthesizing new materials is to react functional pendant groups on an existing polymer. Here, an enzymatic strategy was investigated as a method of producing new polymers from chitosan. The enzyme used was tyrosinase which is known to oxidize a range of phenolic reactants, yielding reactiveo -quinones. The products of this enzymatic oxidation appear to react with, and alter the chemical...
Transition temperatures of water/chitosan systems with water contents ranging from 8 to 300% (weight per cent of water per dry polymer weight) are measured by differential scanning calorimetry (d.s.c.). Upon heating, three kinds of phases, which vary with the water content, are observed for the system: cold crystallization, melting of freezable water, and a birefringent to isotropic phase which occurs...
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