Rheological properties of solutions of chitosan and its graft copolymer with N-vinylcaprolactam

Kholmuminov, A. A.; Kudyshkin, V. O.; Futoryanskaya, A. M.; Avazova, O. B.; Milusheva, R. Yu.; Рашидова, С. Ш.

doi:10.1134/s0965545x10090099

Cited by 5 publications

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“…This reaction was performed under homogeneous conditions using a mixture of solvents at 60 °C. Unfortunately, this reaction is reported to be accompanied by a decrease in the molecular weight of chitosan, probably caused by the cleavage of the glycoside bonds by potassium persulfate [76,77]. In the grafting from technique, the radical chain polymerization of a monomer is triggered by the thermal decomposition of the initiator.…”

Section: Synthesismentioning

confidence: 99%

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Chitosan-Based Thermosensitive Materials

Argüelles‐Monal¹,

Recillas-Mota²,

Fernández‐Quiroz³

2017

Biological Activities and Application of Marine Polysaccharides

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Thermosensitive polymers are materials capable of undergoing a reversible phase transition in aqueous media in response to a variation of the temperature. They have attracted high scientific interest for advanced applications in diverse areas, such as biotechnology, biomedical, environmental, food industry and other fields. At the same time, chitosan is a promising marine polysaccharide that has long been used in applications such as drug, peptide or gene delivery systems. Being the most abundant marine polysaccharide, chitin and chitosan do not exhibit thermoresponsive properties, but some of their derivatives do. In the present chapter, the efforts to produce chitosan-based thermosensitive materials are reviewed. Particularly, the properties and applications of chitosan-glycerophosphate thermogelling system are examined; the methods of synthesis of chitosan copolymers grafted with poly(Nisopropylacrylamide) or poly(N-vinylcaprolactam), their physicochemical properties and most of their prominent applications are discussed as well.

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Section: Synthesismentioning

confidence: 99%

“…These authors suggested that this behaviour is related to the presence of flexible PVCL chain blocks that easily unwind and orient in a flow when increasing the shear rate [77].…”

Section: Propertiesmentioning

confidence: 99%

Chitosan-Based Thermosensitive Materials

Argüelles‐Monal¹,

Recillas-Mota²,

Fernández‐Quiroz³

2017

Biological Activities and Application of Marine Polysaccharides

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“…These factors determine the very complicated behavior of chitosan macromolecules in the solution [17][18][19][20][21][22]. This explains partly the discrepancy between certain literature data on the concentration modes and the critical rheological parameters ( C * , C e ) of chitosan solutions and the diffi culty of comparing them.…”

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confidence: 99%

Rheological Properties of Aqueous Acid Solutions of Chitosan: Experiment and Calculations of the Viscometric Functions on the Basis of a Mesoscopic Model

Shipovskaya

Abramov

Pyshnograi

et al. 2016

J Eng Phys Thermophy

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The rheological properties of chitosan solutions in acetic acid at 20 o C in the range of polymer concentrations from 0.5 to 8 mass% and acid concentrations from 2 to 70% have been investigated. With the use of a modifi ed Vinogradov-Pokrovskii model based on the microstructural approach to the description of polymer fl uid dynamics, numerical solutions of gradient dependences of viscometric functions of aqueous acid solutions of chitosan have been obtained. It has been established that the numerical solution describes with good accuracy the experimental viscosity rheograms. The values of the highest Newton viscosity η max have been calculated. The concentration modes of semidiluted and concentrated solutions have been determined by the dependence of η max on the polymer concentration, and the range of concentrations in which the mass transfer mechanism changes and a fl uctuation network is formed has been found. It has been shown that the concentration of acetic acid practically does not infl uence the structure and character of fl ow of chitosan solutions, the formation concentration of a network, and the effi ciency of its labile nodes.Introduction. Chitosan -a product of partial or complete deacetylation of chitin -is an aminopolysaccharide of linear structure exhibiting in an acid medium the properties of an ionogenic polymer. It shows promise as a substance that can be used in a wide variety of spheres of human life due to a complex of practically valuable properties, as well as a practically inexhaustible (annually renewable) source of raw materials [1][2][3][4][5]. Because of the high adhesion energy, the thermal decomposition temperature of chitosan is lower that its melting temperature. Therefore, processing the given polymer into fi nished articles involves the stage of dissolution in organic or inorganic acids.It is known that the concentration mode is one of the major factors infl uencing many properties of polymer solutions and, consequently, determining the conditions of their processing into a fi nished product [6][7][8]. Such polymer materials as fi lms, fi bers, capsules, etc. are obtained mainly from concentrated solutions. For inorganic polymers, chitosan among them, the diagnostic variable of going from the mode of diluted solutions to the mode of concentrated solutions is the formation concentration of a network C e which in absolute value can exceed several times the crossover concentration C * -overlap of coiled molecules [9][10][11][12][13]. The parameter C e in combination with the concentration and gradient dependences of viscosity η permits not only estimating the features of the structure formation of solutions of polyelectrolytes, but also predicting the conditions for the formation of a polymer material, as well as its structure and properties [14][15][16]. Therefore, the investigation of the rheological characteristics of a chitosan-containing system is of interest both for analysis of the structure of chitosan solutions in various concentration modes and for the technology of obta...

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“…The swelling of samples as a function of CS DD was judged from the d CS /d CT ratio. The behavior with shear flow of the selected samples in H 2 O and acidic solutions was studied on a Rheotest-2 instrument [3].The tests showed that increasing DD resulted in increased swelling of CS samples in H 2 O. The swelling was greater for DD ≥ 90% (Fig.…”

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confidence: 99%

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Flow Behavior of Chitosan Particles

Kodirkhonov

2015

Fibre Chem

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54-18:544.774 Chitin and chitosan with degree of deacetylation (DD) 57, 85, 89, and 90% were obtained as 250-μm microparticles. Their behavior with shear flow in aqueous and acidic solutions was studied. It was found that chitosan microparticles with various DD converted into gels as a result of swelling in water. Chitosan hydrogel particles with DD >85% were destroyed in shear flow without destroying the chains. The macromolecules were ordered in the direction of the flow.Powdered chitosan (CS) is an exceedingly practical product for preparing solutions with broad applications [1]. The powder particles are usually produced by milling CS produced by deacetylation of chitin (CT). This type of chemical transformation destroys the crystal structure of the starting CT. CS with a high degree of deacetylation (DD, >80%) is practically amorphous and dissolves in weakly acidic solutions, in particular HOAc (2%) [2]. Such CS samples swell and form hydrogels in H 2 O.A solvent is not always weakly acidic but often turns out to be closer to neutral or simply H 2 O. In such instances, CS inevitably swells and forms hydrogel particles. Studies of the behavior of CS in H 2 O are important because the hydrogel particles are exceedingly sensitive to the effects of external fields, especially deformations due to flow. The flow of such a solution is characteristically non-Newtonian and was studied in the present work taking into account swelling of CS in a shear flow.CT and CS with DD 57, 85, 89, and 90% were selected for the experiments. Microparticles (250 μm) were prepared by milling samples in a ball mill. The change in the size of CT (d CT ) and CS (d CS ) microparticles after swelling was determined using an optical microscope. The swelling of samples as a function of CS DD was judged from the d CS /d CT ratio. The behavior with shear flow of the selected samples in H 2 O and acidic solutions was studied on a Rheotest-2 instrument [3].The tests showed that increasing DD resulted in increased swelling of CS samples in H 2 O. The swelling was greater for DD ≥ 90% (Fig. 1). This indicated that there was a certain characteristic DD value above which the ability of H 2 O to penetrate into the bulk of the CS samples increased sharply. The CS appeared as hydrogel microparticles that were susceptible to deformations, especially with flow.A comparison of swelled microparticles in shear flow showed that CS had typical non-Newtonian behavior that was more apparent for samples with high DD under large shear stresses (σ) (Fig. 2). The appearance of such behavior, i.e., breaks in the curves for γ < 400 s -1 , was due to deformations of the microparticles. Then, the samples acted as Newtonian fluids for γ > 400 s -1 . Hydrogels with DD ≥ 90% became paste-like. Surely, this resulted from coalescence of compressed deformed hydrogel particles in the flow.In acidic solution, CS not only swelled but also dissolved. These processes were kinetic in nature, depended on the DD, and occurred evenly throughout the whole solution with vigorous ...

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Rheological properties of solutions of chitosan and its graft copolymer with N-vinylcaprolactam

Cited by 5 publications

References 0 publications

Chitosan-Based Thermosensitive Materials

Chitosan-Based Thermosensitive Materials

Rheological Properties of Aqueous Acid Solutions of Chitosan: Experiment and Calculations of the Viscometric Functions on the Basis of a Mesoscopic Model

Flow Behavior of Chitosan Particles

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