I Congreso - Convergencias y divergencias. Hacia educaciones y desarrollo otros.

La presente colección, en su primera publicación, recoge la experiencia del I Congreso Internacional de Educación para el Desarrollo en Perspectiva Latinoamericana- EpDl “Convergencias y divergencias. Hacia educaciones y desarrollos otros.” organizado por el Centro de Educación para el Desarrollo-CED de UNIMINUTO, específicamente en relación con las ponencias, libros e iniciativas fotográficas presentadas en las seis líneas temáticas de este evento académico, a saber: (a) experiencias y prácticas pedagógicas; (b) acciones colectivas, movimientos y redes sociales; (c) perspectivas críticas al desarrollo; (d) producción de conocimiento; (e) diferencias, identidades y ciudadanía; (f) cuerpos, emociones y espiritualidades; a partir de éstas propuestas y en el marco de estas líneas, se reflexionó sobre las dinámicas y problemáticas derivadas del desarrollo hegemónico, así como sobre la posibilidad de diálogo entre saberes y conocimientos construidos de forma contextualizada, que permitan agenciar apuestas y proyectos alternativos disidentes en la búsqueda de “desarrollos y educaciones otras” desde América Latina

FLAME IGNITION MECHANISMS IN POLYMER NANOCOMPOSITES: EXPERIMENTAL EVIDENCES AND INTERPRETATION

In this work, flaming ignition of montmorillonite clay polymer nanocomposites and microcomposites was addressed, showing variable trends in the time to ignition, as compared with the reference polymers. Temperatures on the surface layer of specimens irradiated in the cone calorimeter were measured during the test, to investigate the surface temperature at ignition. Viscosity measurement and in depth radiative absorption measurements were also carried out and correlated with ignition of polymer. Additionally, physical and chemical characterization of the condensed phase at different time, either before or after ignition, were carried out to investigate the evolution of the material during the combustion proces

Ignition of polypropylene/montmorillonite nanocomposites

This paper addresses the flaming ignition of polypropylene and polypropylene-based nanoclay composites, under irradiation in a cone calorimeter. The surface temperature as a function of time was measured using thermocouples on the surface and the chemical changes occurring in the polymer leading to evolution of volatiles were studied by means of spectroscopic analyses of the surface. Thermogravimetric analyses were also carried out to study thermal and thermoxidative volatilization at variable heating rates, which correlate to the production of the critical concentration of combustible volatiles for ignition. The effect of both microdispersed and intercalated nanoclays on ignition time and ignition temperature is addressed and analysed in detail

DNA Coatings from Byproducts: A Panacea for the Flame Retardancy of EVA, PP, ABS, PET, and PA6?

One of the most important challenges for thermoplastic polymers is to find flame retardants (FRs) capable of efficiently protecting them. At the same time, these desired FRs should be environmentally sustainable, cheap, and suitable for most of the polymers employed on the industrial scale. Obviously, it is almost impossible to design such a universal FR to be used for polymers having different chemical structures. We have recently demonstrated the efficiency of a deoxyribose nucleic acid (DNA) coating as a FR solution for cellulose and ethylene-vinyl-acetate (EVA) copolymer. Pursuing this research, in the present study we investigate the FR effect of different DNA amounts on 3 mm EVA samples in order to optimize its cost/effectiveness ratio. FR performances were evaluated with a cone calorimeter under 35 and 50 kW/m². Then, the optimized DNA amount was tested on EVA samples having different thicknesses (namely, 1 and 6 mm) in order to establish whether a correlation between DNA amount and sample mass exists. Finally, the DNA potentialities as “universal” FR have been investigated on samples of polypropylene (PP), acrylonitrile-butadiene-styrene (ABS), polyethyleneterephthalate (PET), and polyamide 6 (PA6) and compared with some of the best FR solutions found in the literature or on the market

How much the fabric grammage may affect cotton combustion?

The present article is addressed to investigating the effect of different fabric grammages (mass per area unit) on cotton combustion. To this aim, 100, 200 and 400\ua0g/m2 cotton fabrics were tested when exposed to (1) two different heat fluxes (25 and 35\ua0kW/m2) under a cone calorimeter, (2) a methane flame in horizontal or vertical flame spread tests or (3) a propane flame in Limiting Oxygen Index tests, and (4) when pyrolysed and further oxidised in pyrolysis-combustion flow calorimetry (PCFC). The collected results demonstrated a precise relationship between fabric grammage and cotton combustion behaviour. Indeed, when exposed to a 35-kW/m2 heat flux, the higher the fabric grammage, the higher the total heat release during combustion was; the opposite trend was observed when the same fabrics were pyrolysed and further oxidised in PCFC. This finding was ascribed to the different scenarios described by these instrumentations; indeed, the cone calorimeter was able to reproduce cotton combustion in a well-ventilated context in the presence of air (thus, oxygen), while PCFC only represented the combustion of pyrolysis products. However, both techniques indirectly evidenced a linear dependence of char formation as a function of fabric grammage: the higher the fabric grammage, the larger the amount of char formed was. The same trend was also observed during horizontal and vertical flame spread tests. In conclusion, the present article is intended to show how cotton combustion may be affected by fabric grammage as well as how such behaviour is influenced by the experimental conditions in which it is investigated

Advanced biobased and rigid foams, based on urethane-modified isocyanurate from oxypropylated gambier tannin polyol

Rigid and biobased urethane-modified isocyanurate (PUIR) foams with an isocyanate/hydroxyl molar ratio equal to 3, were synthesized from glycerol-based and/or gambier tannin-based polyols, obtained by oxypropylation process. The content of each polyol was varied progressively and respectively from 0 to 100%. The synthesized PUIR foams were fully characterized and compared. Density, compressive modulus, thermal conductivity and closed-cell content were studied. Cell morphology was also observed by scanning electron microscopy. Furthermore, thermal stability and flammability were investigated to study the impact of the aromatic structure provided by the tannins. The results show that the tannin-based polyol favors some PUIR foams properties such as fire retardancy and high compressive strength behavio