Compost, oxidized films

The initiation of thermo-oxidation of polyethylene films by transition metal catalysts during composting proceeded slowly compared to oxidation at the same temperature in an oven (60-70 °C) [56]. The starch-filled polyethylene bags exposed on the surface of the compost broke down into small pieces while the buried bags remained intact after 49 days of exposure [55,... 

Applications currently promoted for oxidatively biodegradable plastics include, landfill covers and bags for landfill disposal, agricultural film and a route to alleviate litter. They do not currently meet compost bag use. 

Xylans from batch extraction are also good film formers even though the tensile properties of these films differ slightly from the twin-screw extracts. The difference might be a result of the compostion in minor compounds liable to oxidative cross linking in the twin-screw extract, thus leading to a more rigid film. Combined extrusion of wheat straw and bran leads to an extract witli a... 

The results all show that PE films modified by our additives are oxidatively biodegradable under composting conditions, yielding high-quality compost. No toxic effects could be detected on either seed germination or organism survival. 

Another impact on the environment is the possible production of micro fragments during the biodegradation process. To assess this micro fragment production, experiments conducted in laboratory conditions and real conditions have been set up (Charrier, 2003). Three films were tested (i) polyester aUph/ arom -l- starch, (ii) polyester aUph/arom -i- natural fibres and (iii) polyethylene + pro oxidant. The results are shown in Table 19.4. In test A, samples of films were ineorporated into pots containing a natural soil. These pots were put in an oven at 30 C for six months, and were regularly watered to ensure a constant soil humidity. A similar experiment, test B, was performed in compost... 

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