RESUMEN
In the present study, poly(3-hydroxybuturate-co-3-hydroxyvalerate) (PHBV) and plasticized polylactide acid (PLA) blends were processed by melt extrusion with different weight ratio (up to 20 wt.% of PHBV). Bionanocomposites were obtained through the incorporation of an organomodified montmorillonite (C30B) at 3 wt.%. The main features of the processing and physico-chemical characterization of films and injected samples were assessed and the influence of the components on the chemical, thermal and mechanical properties of the bionanocomposites was investigated. The results indicated that plasticized PLA/PHBV/C30B bionanocomposites present optimal mechanical properties for sanitary applications. Moreover, plasticized PLA/PHBV could lead to finely tuned biomaterials able to form electrospun nanofibers.
RESUMEN
Microalgae were considered in this work as a new resource for developing starch-based bioplastics. Ten green microalgae strains were screened at lab-scale for their ability to produce starch. A long run (800 h) two-stage accumulation strategy was designed with successive cultivation in sulfur-replete, then sulfur-depleted medium in autotrophic conditions. Starch content was assessed on cell lysate by enzymatic digestion of extracted starch into glucose. Chlamydomonas reinhardtii 11-32A strain was selected as it displayed a maximum starch-to-biomass ratio of 49%w/w, 460 h after being switched to a sulfur-deprived medium. Small-scale pilot production (30 L tubular photobioreactor) with C. reinhardtii 11-32A yielded sufficient biomass quantity to investigate its direct plasticization with glycerol in a twin-screw extruder. Microstructural characterization confirmed the ability for starch-enriched microalgae to be homogeneously plasticized, and hence the possibility to use microalgae as a new platform for the development of bioplastics.
RESUMEN
Semi-opaque to opaque films containing small amounts of various aluminium particles to decrease emissivity were easily prepared and coated onto low-density polyethylene (LDPE) sheets. The thermal-radiative properties (reflectivity, transmissivity and absorptivity) of the films were measured and related to the aluminum particles' content, size and nature. Time-to-ignition of samples was assessed using a cone calorimeter at different heat flux values (35, 50 and 75 kW/m²). The coatings allowed significant ignition delay and, in some cases, changed the material behaviour from thermally thin to thick behaviour. These effects are related both to their emissivity and transmissivity. A lower emissivity, which decreases during the degradation, and a lower transmissivity are the key points to ensure an optimal reaction-to-fire.