Preliminary evaluation of risks related to waste incineration of polymer nanocomposites.

If nanotechnology proves to be successful for bulk applications, large quantities of nanocomposites are likely to end up in municipal solid waste incineration (MSWI) plants. Various studies indicate that nanoobjects might be harmful to human health and the environment. At this moment there is no evidence that all nanoobjects are safely removed from the off-gas when incinerating nanocomposites in MSWI plants. This paper presents a preliminary assessment of the fate of nanoobjects during waste incineration and the ability of MSWI plants to remove them. It appears that nanoobject emission levels will increase if bulk quantities of nanocomposites end up in municipal solid waste. Many primary and secondary nanoobjects arise from the incineration of nanocomposites and removal seems insufficient for objects that are smaller than 100nm. For the nanoobjects studied in this paper, risks occur for aluminum oxide, calcium carbonate, magnesium hydroxide, POSS, silica, titanium oxide, zinc oxide, zirconia, mica, montmorillonite, talc, cobalt, gold, silver, carbon black and fullerenes. Since this conclusion is based on a desktop study without accompanying experiments, further research is required to reveal which nanoobjects will actually be emitted to the environment and to determine their toxicity to human health.

Comparative life cycle studies on poly(3-hydroxybutyrate)-based composites as potential replacement for conventional petrochemical plastics.

A cradle-to-grave environmental life cycle assessment (LCA) of a few poly(3-hydroxybutyrate) (PHB) based composites has been performed and was compared to commodity petrochemical polymers. The end products studied are a cathode ray tube (CRT) monitor housing (conventionally produced from high-impact polystyrene, HIPS) and the internal panels of an average car (conventionally produced from glass-fibers-filled polypropylene, PP-GF). The environmental impact is evaluated on the basis of nonrenewable energy use (NREU) and global warming potential over a 100 years time horizon (GWP100). Sugar cane bagasse (SCB) and nanoscaled organophilic montmorillonite (OMMT) are used as PHB fillers. The results obtained show that, despite the unsatisfying mechanical properties of PHB composites, depending on the type of filler and on the product, it is possible to reach lower environmental impacts than by use of conventional petrochemical polymers. These savings are mainly related to the PHB production process, while there are no improvements related to composites preparation. SCB-based composites seem to be environmentally superior to clay-based ones.