Poly composting conditions

PLA may be fabricated into film for packaging and is also made into fibers useful for carpeting (24). PLA is indeed biodegradable, but only under controlled composting conditions. Biodegradation of poly (lactic acid) requires temperatures of about 140 °F for many days to insure decomposition, ultimately into CO and water. Unfortunately, such conditions are not typical of landfills (3) or of most backyard compost heaps. Hence, even plastic bags made from PLA will not quickly disappear from the natural environment. Anaerobic decomposition of PLA results in liberation of methane, an even more potent greenhouse gas than CO (25-28). 

Ohtaki A, Sato N, Nakasaki K. Biodegradation of poly-e-caprolactone under controlled composting conditions. Polym Degrad Stab 1998 61 499-505. 

PLA Poly(lactic acid) commercial bottles and deh containers Composting under real conditions (compost pile temp. 65°C moisture 63%, pH 8.5) visual inspection molecular weight changes (GPC method) glass transition and melting temperature (DSC method) decomposition temperature (TGA method). Degradation of PLA containers <30 days under composting conditions [26]... 

Poly(lactic acid) (PLA) is a thermoplastic polyester characterized by mechanical and optical properties similar to polystyrene (PS) and polyethylene terephthalate (PET). It is obtained from natural sources, completely biodegradable and compostable in controlled conditions as already stated in previous chapters. PLA offers some key points with respect to classic synthetic polymers, since it is a bioresource and renewable, while raw materials are cheap and abundant compared to oil. From a commercial point of view, a non-secondaiy approach, it can embellish with the word green so fashioned for the major stream consumers. Legislation can also help the commercial diffusion of biopolymers. As an example, a decisive leap has been made with the control of non-biodegradable shopping bags distribution in the European Commission and many of its member states. In addition, PLA has received some interest from the industrial sectors because of its relatively low price and commercial availability compared with other bioplastics. This is the veiy key point for any successful polymer application. In fact, the current price of commercial PLA falls between 1.5 and 2 kg , which is sufficiently close to other polymers like polyolefins, polyesters or poly(vinyl chloride) (PVC). Clearly, the PLA market is still in its infancy, but it is expected that the decrease in the production costs and the improvement in product performance will result in a clear acceleration in the industrial interest for PLA uses. It is estimated that PLA consumption should reach... 

The biodegradabihty of native and compatibilized poly(e-caprolactone) (PCL)-granular starch blends in composting and culture conditions was studied. The inherent biodegradability of the host polyester has been shown to increase with compatibilization within the PCL-starch compositions [131]. It was observed that the weight loss during composting increased with the... 

Biodegradation of plastics was tested in the compost stored at -20°C, 4°C and 20°C for different periods [152], It was found that biodegradation of cellulose in the compost was almost independent of the storage time and temperature. In contrast, biodegradability of both polycaprolactone (PBS) and poly(butylene succinate) (PBS) depended strongly on the storage conditions. 

Kale G., Aura R., Singh S.P Comparison of the degradability of poly(lactide) packages in composting and ambient exposure conditions, Packag. Technol Sci. 20 (2007) 49. 

Using similar conditions in another study [57] the weight loss of 55 pm films of a BTA-based copolyester containing approximately 55 mol% terephthalic acid was tested in the same kind of soil and was compared with the degradation of poly(e-caprolactone) (PCL Tone787, Union Carbide, films of 75 pm thickness) (Figure 10.5) in soil and in compost... 

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