Chemical modification of chitosan under high-intensity ultrasound

Cravotto, Giancarlo; Tagliapietra, Silvia; Robaldo, Bruna; Trotta, Michele

doi:10.1016/j.ultsonch.2004.03.005

Cited by 71 publications

(35 citation statements)

References 21 publications

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“…Mechanical, thermal and active effects generated by ultrasonic and liquid medium make ultrasonic wave applied in surface engineering and electrochemistry [25]. At the same time, ultrasound is beneficial to inducing chemical modification on many materials [26,27]. Ultrasound would have cavitation effect when the ultrasonic power density is equal to or greater than 0.3 W/cm 2 .…”

Section: Introductionmentioning

confidence: 99%

Microstructure and corrosion resistance of ultrasonic micro-arc oxidation biocoatings on magnesium alloy

Liu

et al. 2013

J Adv Ceram

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Abstract:The ultrasonic micro-arc oxidation (UMAO) was used to fabricate ceramic coatings on magnesium alloy. UMAO coatings were produced at 60 W input ultrasonic. The effects of the ultrasound on the microstructure, phase composition, elemental distribution and corrosion resistance of the coatings were extensively investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectrometry (EDX) and electrochemical workstation. The results showed that ultrasound improved the homogeneous distribution of micro-porous structure. The coatings were mainly composed of MgO ceramic and small amount of calcium and phosphorus with porous structure. The Ca/P ratio of the coatings increased when 60 W ultrasonic was used. The corrosion potential in simulated body fluid (SBF) changed from 1.583 V of bare magnesium alloy to 0.353 V of magnesium alloy coated under 60 W ultrasonic. The corrosion resistance of UMAO coatings was better than that of MAO coatings.

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Section: Introductionmentioning

confidence: 99%

Microstructure and corrosion resistance of ultrasonic micro-arc oxidation biocoatings on magnesium alloy

Liu

et al. 2013

J Adv Ceram

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“…Chitosan is an insoluble substance in aqueous solutions with pH values corresponding to neutral or alkaline characters (Cravotto, Tagliapietra, Robaldo, & Trotta, 2005). Then, the use of this substance is limited to processes using this polymer in organic acid solutions.…”

Section: Introductionmentioning

confidence: 99%

Physicochemical characterization of chitosan derivatives

Seoane

Abuín

Gómez‐Díaz

et al. 2013

CyTA - Journal of Food

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The present work analyses different chitosan synthesized derivatives from the point of view of their chemical structure (Fourier transform infrared spectroscopy, deacetylation degree, elemental analysis and average molecular weight) as well as different physicochemical properties such as density, kinematic and dynamic viscosity, intrinsic viscosity and surface tension. The characterization of different solutions of these solutes has a high importance due to the large potential uses of these compounds. Chitosan has low solubility in water, and for this reason, the present work has synthesized soluble chitosan derivatives. Important differences between original chitosan and synthesized derivatives have been found in different properties.Keywords: chitosan; derivatives; viscosity; surface tension El presente trabajo analiza distintos derivados sintetizados del quitosano desde el punto de vista de su estructura quı´mica (FTIR, grado de desacetilacio´n, ana´lisis elemental y peso molecular medio), ası´como de distintas propiedades fı´sico-quı´mica como son la densidad, viscosidad cinema´tica y dina´mica, viscosidad intrı´nseca y tensio´n superficial. La caracterizacio´n de las disoluciones acuosas de estos solutos tiene una elevada importancia debido al gran potencial en el uso de estos compuestos. El quitosano tiene una baja solubilidad en agua y por este motivo este trabajo ha sintetizado derivados solubles de quitosano. Se han encontrado diferencias importantes en algunas propiedades entre los resultados experimentales correspondientes al quitosano y a sus derivados.

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“…In addition, chitosan amino nucleophilic sites on the polymer backbone provide means of easier and selective synthetic transformations of these polymers to obtain various derivatives as may be necessary toward developing targeted applications, thus chitosan derivatives have been prepared and their antioxidant properties were studied [18][19][20][21][22][23][24]. A series of chemical modifications of chitosan, comprising N-or O-selective functionalization was carried out [25]. The chemical modifications of chitosan by introducing new functional groups not only enlarge its applications, but also enhance chitosan's solubility in slightly acid, neutral and alkaline media and improve its water solubility [26].…”

Section: Introductionmentioning

confidence: 99%