Browsing by Author "Kortaberria, Galder"

Now showing 1 - 7 of 7
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    Biocomposites with increased dielectric constant based on chitosan and nitrile-modified cellulose nanocrystals
    (2018) Bonardd Salvador, Sebastián Ignacio; Robles, Eduardo; Barandiaran, Irati; Saldias, Cesar; Leiva Campusano, Ángel; Kortaberria, Galder
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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.
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    Interaction of dendronized polymeric nanocomposites with isomeric cyclohexanediols
    (2015) Alvarado Almonacid, Nancy Alicia; Fuentes, Irma; Leiva Campusano, Ángel; Radić Foschino, Deodato D.; Alegría Aguirre, Luz Katiushka; Kortaberria, Galder; Eceiza, María Arantxa; Gargallo Gómez, Ligia Teresita
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    Molecular Weight Enables Fine-Tuning the Thermal and Dielectric Properties of Polymethacrylates Bearing Sulfonyl and Nitrile Groups as Dipolar Entities
    (2021) Bonardd, Sebastian; Saldias, Cesar; Leiva, Angel; Diaz Diaz, David; Kortaberria, Galder
    In this work, polymethacrylates containing sulfonyl and nitrile functional groups were successfully prepared by conventional radical polymerization and reversible addition-fragmentation chain-transfer polymerization (RAFT). The thermal and dielectric properties were evaluated, for the first time, considering differences in their molecular weights and dispersity values. Variations of the aforementioned properties do not seem to substantially affect the polarized state of these materials, defined in terms of the parameters epsilon'(r), epsilon"(r) and tan (delta). However, the earlier appearance of dissipative phenomena on the temperature scale for materials with lower molecular weights or broader molecular weight distributions, narrows the range of working temperatures in which they exhibit high dielectric constants along with low loss factors. Notwithstanding the above, as all polymers showed, at room temperature, epsilon'(r) values above 9 and loss factors below 0.02, presenting higher dielectric performance when compared to conventional polymer materials, they could be considered as good candidates for energy storage applications.
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    Polyitaconates a new family of all polymer dielectrics
    (2018) Bonardd Salvador, Sebastián Ignacio; Alegria, Angel; Saldías, César; Leiva Campusano, Ángel; Kortaberria, Galder
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    Synthesis of new poly(itaconate)s containing nitrile groups as high dipolar moment entities for the development of dipolar glass polymers with increased dielectric constant. Thermal and dielectric characterization
    (2019) Bonardd, Sebastian; Alegria, Angel; Saldias, Cesar; Leiva, Angel; Kortaberria, Galder
    This work presents the synthesis of new poly(itaconate)s containing one or two nitrile pendant groups through conventional radical polymerization. To the best of our knowledge, this is the first time in which the synthesis of poly(itaconate)s containing nitrile groups is reported in the literature. The effect of nitrile groups on the main properties is analyzed. Polymer structures were confirmed by Fourier transform infrared spectroscopy (FTIR), H-1 and C-13 NMR. Molecular weights were measured by size exclusion chromatography (SEC), while thermal characterization was achieved by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Dielectric properties were measured using broadband dielectric spectroscopy at different temperatures. Polymers with one or two nitrile groups presented dielectric constant values (at 25 degrees C and 1 kHz) of around 7 and 12.5, respectively, with relatively low dielectric losses with values below 0.02. BDS measurements showed notorious sub-glass transitions attributed to the movement of the dipolar groups under the electric field, even below - 100 degrees C, allowing to achieve dielectric constant values above the average for polymers even at extremely low temperatures. Therefore, these materials could be considered as good candidates for energy storage applications.