Foams produced from blends of an ethylene‐vinyl acetate copolymer (EVA) with high VA (vinyl acetate) content (28%) and corn starch have been successfully fabricated using an improved compression molding technique. A detailed characterization of the structure and physical properties has been carried out. The results showed that the corn starch acts as filler for EVA, showing a good compatibility with the polyolefin. Different types of cellular structure (closed, partially interconnected, and fully interconnected) and cell sizes were obtained depending on the relative density and the amount of starch included in the composition. Besides, the addition of starch allows tailoring the physical properties of the composite foams. An increase in the starch content leads to an increase of the density, compressive strength, hardness, and thermal conductivity and a decrease of the elasticity. Finally, biodegradability tests showed how increases the biodegradation with the amount of starch in the foam, which reaches 60% at 100 days for the foam with 70% of starch. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers

Composites of etylene vinyl acetate (EVA)/aluminum trihydroxide (ATH) (up to 70 wt%) were foamed to create new materials with good fire retardancy properties and low weight, proving the feasibility of developing cellular structures when high levels of halogen-free flame retardants (HFFR) are included. An experimental study was carried out to explore the effects of chemical composition on cellular structure as well as the effect of structure on thermal stability, mechanical and combustion properties. Sample fabrication was carried out using an improved compression molding route consisting of polymer compounding, precursor preparation and foaming under pressure. The polymer matrix consisted of EVA as well as certain amount of linear low-density polyethylene-maleic anhydride as coupling agent. The inorganic filler used was ATH ranging from 0 wt% to 70 wt%. Furthermore, azodicarbonamide was used as chemical blowing agent. Foamed samples with cell sizes below 100 µm were produced. These samples showed similar fire retardancy than their solid precursors. The compatibilization was proved indispensable to achieve a good adhesion between mineral filler and polymer and to improve the cellular structure. The increase of the amount of filler has an interesting effect on the cellular structure, going from a closed-cell (up to 50 wt% of ATH) to an open-cell cellular structure (60 wt% of ATH or more). The feasibility of producing HFFR cellular materials has been demonstrated as a result of this investigation, leading to a notable reduction of material compared to the solid one and to new properties which can result in new applications.

Composites of LDPE/ATH (up to 70 wt.%) were foamed to create new materials with good fire retardancy properties and low weight, proving the feasibility of developing cellular structures when high levels of inorganic fillers are included. An experimental study was carried out to explore the effects of chemical composition on cellular structure as well as the effect of structure on their thermal, mechanical and combustion properties. Samples fabrication was carried out using an improved compression moulding route consisting of polymer compounding, precursor preparation and foaming under pressure. The polymer matrix consisted of low density polyethylene as well as certain amount of LLDPE-g-MAH as compatibilizer agent. The inorganic filler used was aluminium trihydroxide (ATH) ranging from 0 wt.% to 70 wt.%. Furthermore, azodicarbonamide (ADC) was used as chemical blowing agent. Foamed samples with cell sizes below 100 microns were produced. These samples showed similar fire retardancy than their solid precursors. The compatibilization was proved indispensable to achieve a good adhesion between mineral filler and polymer and to improve the cellular structure. The increase of the amount of filler has an interesting effect on the cellular structure, going from a closed-cell (at low contents) to an open-cell (at higher contents) cellular structure. As a result of this investigation, halogen-free flame retardant cellular materials were processed, leading to a notable reduction of material compared to the solid one and to new properties which can result in new applications.

Mayor advances have been made in the field of halogen-free flame retardant composites in the last years, mainly due to increasing regulatory pressures. This paper focuses in aluminium trihydroxide (ATH) as the halogen-free flame retardant and low density polyethylene (LDPE) as the polymer matrix of the fire retardancy foam. The attempt of this article is to achieve a cellular structure by foaming these materials, when high loading levels (up to 60wt %) of ATH are introduced. This is a difficult task due to the high amount of filler in the formulation. The aim is to reduce density without losing thermal and mechanical properties. In order to characterize the cellular structure as well as the thermal, mechanical and combustion properties, a complete study of the foamed samples was made by means of scanning electronic microscopy (SEM), thermogravimetric analysis (TGA), melt flow index (MFI), air pycnometry, mechanical testing at low strain rates, limiting oxygen index (LOI) and calorimeter bomb tests.

For many years, coal has been the main economic engine of several European regions, including the province of León in the northwest of Spain. However, the ongoing energy transition has led to a massive closure of coal mines and high uncertainty within the mining industry. The current decline of the mining sector in these regions has triggered severe depopulation, jobs losses and a general industrial decay. Valorisation of tailings has proved effective as a way of revitalising these areas, but more knowledge is needed in order to fully exploit this potential. This study presents a method for the development of a new database with information on existing tailings in the province of León, based on scattered data extracted from public resources. The database includes a comprehensive set of data related to these tailings, including administrative, geographical and geological data. The purpose of this database is to constitute a valuable source of information of the existing mineral resources of the region, as well as to raise awareness on the great potential for technological valorisation of these raw and specific materials. Preliminary results and conclusions are reported. Further development of this work is expected to have positive effects regarding transfer and generation of knowledge, business opportunities and social recovery of the region, all in line with the UN Sustainable Development Goals, the priorities of the European Commission on raw materials and the Circular Economy strategy.