FRLP - I+D+i - CENTROS - CITEMA - TRABAJOS DE INVESTIGACIÓN

Permanent URI for this collectionhttp://48.217.138.120/handle/20.500.12272/1750

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    Chitosan-graft-poly(n-butyl acrylate) copolymer Synthesis and characterization of a natural synthetic hybrid material
    (2016) Anbinder, Pablo; Macchi, Carlos; Amalvy, Javier; Somoza, Alberto
    Two chitosan polymers with different deacetylation degree and molecular weight were subjected to graft- ing reactions with the aim to enhance the properties of these bio-based materials. Specifically, n-butyl acrylate in different proportions was grafted onto two different deacetylation degree (DD%) chitosan using radical initiation in a surfactant free emulsion system. Infrared spectroscopy was used to confirm grafting and products grafting percentage and efficiency were evaluated against acrylate/chitosan ratio and DD%. Thermal and structural properties and the behavior against water of the raw and grafted biopolymers were studied using several experimental techniques: differential scanning calorimetry, transmission electron microscopy, dynamic light scattering, water swelling, contact angle and positron annihilation lifetime spectroscopy. The influence of the grafting process on the morphological and physicochemical properties of the prepared natural/synthetic hybrid materials is discussed.
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    Effect of antioxidant active films on the oxidation of soybean oil monitored by Fourier transform infrared spectroscopy
    (2014) Anbinder, Pablo; Peruzzo, Pablo; Martino, Miriam; Amalvy, Javier
    An active film prepared from waterborne polyurethane incorporated with different concentrations of butylated hydroxytoluene (BHT) and a-tocopherol was developed, and the films’ antioxidant character- istics were studied using soybean oil as food model. The release behavior of additives from such films was studied using isooctane as a simulant fatty food. Antioxidant activity of the films into soybean oil at three experimental conditions was monitored by FTIR spectroscopy. Induction time and the kinetics of the oxi- dation process were followed using different bands of the FT-IR spectra. Films incorporated with 2 wt.% of BHT or a-tocopherol showed enough antioxidant activity to preclude oil oxidation during 60 days at 60 °C in the dark. The results showed that this type of active films could be used for food preservation as part of a packaging containing oils or oily related products.
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    Morphology and properties of neutralized chitosan-cellulosenanocrystals biocomposite films
    (2016) Corsello, Flavia Anahí; Bolla, Patricia Araceli; Anbinder, Pablo; Serradell, María de los Ángeles; Amalvy, Javier; Peruzzo, Pablo
    Chitosan/cellulose nanocrystals (CH-CN) films were obtained by casting of dispersions, and treated with NaOH for neutralization proposes. The composition of films was varied from 1 to 10 wt.% of CN. Changes in the morphology of the systems were correlated with the different properties studied. FTIR revealed the presence of a weak interaction between the polymer matrix and nanofiller, confirmed by a slightly increase in thermal stability. SEM images suggested that incorporating CN amounts higher than 3 wt.% generates phase-segregated systems, and SAXS showed that CH avoid the typical organization of CN at concentrations below 5 wt.%. Improved performance against water was obtained in composite materials comparing to the pure polymer matrix, as well as CH and CH-CN films did not show antibacterial activity demonstrating that remnant acetic acid, when no neutralization step is done, plays an important role in this property.
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    On the strategies for incorporating nanosilica aqueous dispersion in the synthesis of waterborne polyurethane silica nanocomposites, Effects on morphology and properties
    (2016) Peruzzo, Pablo; Anbinder, Pablo; Pardini, Francisco; Pardini, Oscar; Plivelic, Tomas; Amalvy, Javier
    In this work the synthesis of waterborne polyurethane/nanosilica nanocomposites by using two differ- ent strategies is presented, starting from a vinyl terminated polyurethane prepolymer (PUP) based on isophorone diisocyanate and polypropylene glycol, and varying the nanosilica content. In one case, the PUP was dispersed in an aqueous solution containing glycerol-functionalized colloidal nanosilica parti- cles and the dispersion was further polymerized; in the other case, the PUP was dispersed in an aqueous media, then colloidal nanosilica was added to the dispersion and then polymerized. A physical mixture was also prepared for comparative purpose. Films were prepared by casting of the aqueous dispersion. The morphology of the dispersions and films depended on the incorporation route of nanoparticles as was observed by SAXS, SEM and TEM. While the blends had significantly less hydrogen bonding between the hard segments of the PU and nanosilica particles, samples prepared by the two different methods proposed in this work showed an strong interaction between both materials in agreement with FTIR and DSC results. Synthesis pathway plays an important role in order to obtain high performance waterborne polyurethane/nanosilica composites, since final properties of the films also depended on the nanoparticle incorporation strategy.
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    Surface, thermal, and mechanical properties of composites and nanocomposites of polyurethane PTFE nanoparticles
    (2014) Anbinder, Pablo; Peruzzo, Pablo; de Siervo, A.; Amalvy, Javier
    Films from blends of polyurethane and nano-polytetrafluoroethylene aqueous dispersions (PU/nanoPTFE) were prepared, and the effect of the addition of different amounts of PTFE nanoparticles (50 nm) was studied. The changes in the superficial properties of the films were studied by means of XPS, ATR/FTIR, and contact angle measurements. SEM and TEM results are also included. The contact angle values confirm the surface hydrophobicity of com- posite films. Even though nanoparticles are present in the bulk, higher concentrations of particles appear at the surface in samples with lower nanoPTFE content (up to 10 wt%), as revealed by XPS. Higher amounts of nanoPTFE particles cause aggregation. The mechanical and thermal properties of composites are also discussed.