Browsing by Author "Castro, Cristian"

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    Blends containing chitosan and poly(sodium-4-styrene sulphonate). Compatibility behavior
    (ELSEVIER SCI LTD, 2011) Castro, Cristian; Gargallo, Ligia; Radic, Deodato; Kortaberria, Galder; Mondragon, Inaki
    The phase behavior of blends containing chitosan (CS) and poly(sodium-4-styrene sulphonate) (PSS) was analyzed by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), fourier transform infrared spectroscopy (FOR), dielectric spectroscopy (DRS) and atomic force microscopy (AFM). FTIR and DRS analysis seem to indicate the existence of interactions between sulphonate groups of PSS and -NH2 or -OH or both groups of CS. The study of blends by AFM showed a completely different morphology when compared with that of pure components as nanocrystalline domains appeared as globular agglomerates containing more or less spherical particles instead of the independent nanodomains seen in the neat components, possibly as consequence of interactions between both polymers. (C) 2010 Elsevier Ltd. All rights reserved.
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    Blends of chitosan and poly(sodium-4-styrene sulphonate). Compatibilization by lysine and glutamic acid
    (ELSEVIER SCI LTD, 2010) Castro, Cristian; Gargallo, Ligia; Radic', Deodato; Mondragon, Inaki; Kortaberria, Galder
    Polymer blends of chitosan (CS) and poly(sodium-4-styrene sulphonate) (PSS) have been compatibilized using lysine (LYS) and glutamic acid (GLU). Blends of CS/PSS containing LYS and GLU have been studied by thermal analysis. The values of T-g for CS/PSS-LYS blends could not be detected by thermal analysis but one single T-g was found for CS/PSS-GLU blends. Thermogravimetric analysis (TGA) showed that blends decompose at lower temperatures than that of pure components. Displacements in the main absorption bands in the FT-IR spectra were not clear to discern compatibility. Atomic force microscopy (AFM) indicated that addition of lysine or glutamic acid clearly modified the compatibility of the blends. The globular domains existing in the unmodified blend changed to more or less linear and smooth crystalline domains with parallel periodicity. Dielectric analysis revealed that compatibilizer addition changed the secondary relaxation process of PSS to higher temperatures as a result of the modification on interactions. No variation on the segmental dynamics of both polymers was observed as their main relaxations remained unchanged after the addition of lysine or glutamic acid. (C) 2010 Elsevier Ltd. All rights reserved.