Case study of raw materials substitution: Natural fillers substitution in plastic composites

Abstract

In the frame of European problems of raw materials availability, this chapter describe a new technology (COSMOS) that allows to produce safe materials, starting from toxic ash waste (derived from municipal solid waste incineration). It is shown that this technology was evolved in the years to reduce its environmental costs and to use local available by-products for stabilization. The by-products and wastes that can be used in the COSMOS technology are coal fly ash, flue-gas desulfurization residues, rice husk ash, silica fume, and wood ash. The sustainability of the obtained COSMOS materials is demonstrated on the basis of their embodied energy and carbon footprint values. These parameters are reported and discussed also for several natural and engineered materials used as fillers, with great attention also to their cost. Results show that the new proposed material is comparable to calcium carbonate, in term of sustainability. A rapid analysis of the European plastic market and the results about mechanical performances of the obtained composites, highlights the possibility to reuse COSMOS filler as a substitute of calcite and talc, in polypropylene composites. Embodied energy and carbon footprint of the already available polypropylene composites and the new proposed ones are presented and discussed. In this context, Ashby plot is used to investigate possible substitution of polypropylene fillers that are unsustainable or very expensive, exploring the potential of one material to replace another. Finally, in view of its thermal properties the COSMOS filler is proposed as a substitute of antimony, one critical raw material, that urgently need alternative.