Disintegrability under composting conditions of plasticized PLA–PHB blends

The disintegration under composting conditions of films based on poly(lactic acid)–poly(hydroxybutyrate) (PLA–PHB) blends and intended for food packaging was studied. Two different plasticizers, poly(ethylene glycol) (PEG) and acetyl-tri-n-butyl citrate (ATBC), were used to limit the inherent brittleness of both biopolymers. Neat PLA, plasticized PLA and PLA–PHB films were processed by melt-blending and compression molding and they were further treated under composting conditions in a laboratory-scale test at 58 ± 2 °C. Disintegration levels were evaluated by monitoring their weight loss at different times: 0, 7, 14, 21 and 28 days. Morphological changes in all formulations were followed by optical and scanning electron microscopy (SEM). The influence of plasticizers on the disintegration of PLA and PLA–PHB blends was studied by evaluating their thermal and nanomechanical properties by thermogravimetric analysis (TGA) and the nanoindentation technique, respectively. Meanwhile, structural changes were followed by Fourier transformed infrared spectroscopy (FTIR). The ability of PHB to act as nucleating agent in PLA–PHB blends slowed down the PLA disintegration, while plasticizers speeded it up. The relationship between the mesolactide to lactide forms of PLA was calculated with a Pyrolysis–Gas Chromatography–Mass Spectrometry device (Py–GC/MS), revealing that the mesolactide form increased during composting.

Combined Effect of Poly(hydroxybutyrate) and Plasticizers on Polylactic acid Properties for Film Intended for Food Packaging

Poly(lactic acid) PLA, and poly(hydroxybutyrate) PHB, blends were processed as films and characterized for their use in food packaging. PLA was blended with PHB to enhance the crystallinity. Therefore, PHB addition strongly increased oxygen barrier while decreased the wettability. Two different environmentally-friendly plasticizers, poly(ethylene glycol) (PEG) and acetyl(tributyl citrate) (ATBC), were added to these blends to increase their processing performance, while improving their ductile properties. ATBC showed higher plasticizer efficiency than PEG directly related to the similarity solubility parameters between ATBC and both biopolymers. Moreover, ATBC was more efficiently retained to the polymer matrix during processing than PEG. PLA–PHB–ATBC blends were homogeneous and transparent blends that showed promising performance for the preparation of films by a ready industrial process technology for food packaging applications, showing slightly amber color, improved elongation at break, enhanced oxygen barrier and decreased wettability.

La representación mediática del deportista con discapacidad en el reportaje televisivo. Informe Semanal, un estudio de caso

El tratamiento informativo de los Juegos Paralímpicos de 2008 en los medios españoles aparece ligado casi exclusivamente a los valores asociados al universo deportivo, según un estudio previo. Los paralímpicos son atletas, no personas con discapacidad. Ni se tendió al sensacionalismo ni se ofreció una imagen estereotipada. Debido a la particularidad del acontecimiento, también desaparecen reivindicaciones y problemas. Se trata de información deportiva en la que importa el resultado, los éxitos, las medallas. Para profundizar en la comprensión de la representación televisiva de los deportistas con discapacidad, el objeto de estudio es ahora la información televisiva al margen de la dinámica noticiosa de la cobertura diaria de los Juegos. El análisis de otro tipo de piezas, reportajes, ha permitido descubrir marcas tendentes a la estereotipación vinculadas al campo semántico periodístico, aquel que se hace visible a través del uso de recursos que propician la emotividad y la espectacularización. Emergen las historias de vida y detalles íntimos. Los protagonistas muestran una gran autoestima y una autoidentidad positiva al alejarse de las representaciones sociales habituales de la discapacidad.