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Yerevan, Armenia

Hambardzumyan A.,French National Institute for Agricultural Research | Hambardzumyan A.,University of Reims Champagne Ardenne | Hambardzumyan A.,State Erevan University | Foulon L.,French National Institute for Agricultural Research | And 5 more authors.
Biomacromolecules | Year: 2012

Novel nanocomposite coatings composed of cellulose nanocrystals (CNCs) and lignin (either synthetic or fractionated from spruce and corn stalks) were prepared without chemical modification or functionalization (via covalent attachment) of one of the two biopolymers. The spectroscopic properties of these coatings were investigated by UV-visible spectrophotometry and spectroscopic ellipsometry. When using the appropriate weight ratio of CNC/lignin (R), these nanocomposite systems exhibited high-performance optical properties, high transmittance in the visible spectrum, and high blocking in the UV spectrum. Atomic force microscopy analysis demonstrated that these coatings were smooth and homogeneous, with visible dispersed lignin nodules in a cellulosic matrix. It was also demonstrated that the introduction of nanoparticles into the medium increases the weight ratio and the CNC-specific surface area, which allows better dispersion of the lignin molecules throughout the solid film. Consequently, the larger molecular expansion of these aromatic polymers on the surface of the cellulosic nanoparticles dislocates the π-π aromatic aggregates, which increases the extinction coefficient and decreases the transmittance in the UV region. These nanocomposite coatings were optically transparent at visible wavelengths. © 2012 American Chemical Society. Source


Hambardzumyan A.,French National Institute for Agricultural Research | Hambardzumyan A.,University of Reims Champagne Ardenne | Hambardzumyan A.,State Erevan University | Foulon L.,French National Institute for Agricultural Research | And 11 more authors.
Chemical Engineering Journal | Year: 2015

Within the framework of research on the valorization of by-products from 2nd generation biorefineries, we designed novel nanocomposite materials composed of lignin and cellulose nanocrystals. These nano-composites were in the form of thin films which could be self-supported or supported on glass or quartz slides. These materials were prepared by coating or casting the polymer mixtures at ambient conditions. The lignins used included synthetic lignin oligomers as standards and organosolv lignin fractions from maize stalks and spruce wood. The Fenton's reagent was incorporated into the polymeric mixture to improve the dispersion of lignin and to facilitate its grafting onto the surface of cellulose nanocrystals. This grafting process improved the anti-UV property, water resistance, water retention of the thickener films and micromechanical properties of cellulose/lignin films. On the nanocomposite market, the combination of these physico-chemical properties with known antibacterial property of lignin on one hand and oxygen barrier property of cellulose nanocrystal films on the other hand, would make relevant the use of these films in food and non-food (medical, packaging, surface coverings) application fields. © 2014 Elsevier B.V. Source

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