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OXO Biodegradable OXO-biodegradation is defined by CEN (the European Standards Organisation) as "degradation resulting from oxidative and cell-mediated phenomena, either simultaneously or successively." Whilst sometimes inaccurately described as "OXO-fragmentable" and as "OXO-degradable" this describes only the first or oxidative phase. These descriptions should not be used for material which degrades by the process of OXO-biodegradation defined by CEN, and the correct description is "OXO-biodegradable." For the sake of clarity, there are two very different types of biodegradable plastic. they are as follows: 1 - Oxo-biodegradable plastic - made from polymers such as PE (polyethylene) PP (polypropylene) and PS (Polystyrene) containing extra ingredients (NOT heavy metals) and tested according to ASTM D6954 or BS8472 or AFNOR AC T51-808 to degrade and biodegrade in the open environment. and 2 - Vegetable based plastics (also loosely knows as bio-plastics "bioplastics" or "compostable plastics") These are tested in accordance with ASTM D6400 or EN13432 to biodegrade in the special conditions found only in industrial composting or biogas facilities. XXXThis last point omits that various biomass plastics can biodegrade in sunlight and/or with water. OXO-bio plastic is conventional polyolefin plastic to which has been added small amounts of metal salts, none of which are "heavy metals" which are restricted by the EU Packaging Waste Directive 94/62 Art 11. These salts catalyze the degradation process to speed it up so that the OXO plastic will degrade abiotically at the end of its useful life in the presence of oxygen much more quickly than ordinary plastic. At the end of that process it is no longer visible, it is no longer a plastic as it has been converted via Carboxylation or Hydroxylation to small-chain organic chemicals which will then biodegrade. It does not therefore leave fragments of plastic in the environment. The degradation process is shortened from decades to years and/or months for abiotic degradation and thereafter the rate of biodegradation depends on the micro-organisms in the environment. It does not however need to be in a highly microbial environment such as compost. Timescale for complete biodegradation is much shorter than for "conventional" plastics which, in normal environments, are very slow to biodegrade〔http://cmore.soest.hawaii.edu/cruises/super/biodegradation.htm (Marine Laboratory, 1993 )〕 and cause large scale harm. The useful life of a product made using oxo-biodegradable plastic can be programmed at manufacture, typically 6 months for a bread wrapper and 18 months for a lighweight, plastic carrier bag to allow for re-use. Oxo-biodegradable plastic can be manufactured with the existing machinery and workforce in factories at little or no extra cost. They have the same strength and other characteristics as ordinary plastics during their intended lifetime. ==Degradation process== Degradation is a process that takes place in many materials. The speed depends on the environment. Conventional polyethylene (PE) and polypropylene (PP) plastics will typically take decades to degrade. But OXO-biodegradable products utilize a prodegradant to speed up the molecular breakdown of the polyolefins and to incorporate oxygen atoms into the resulting low molecular mass molecules. This chemical change enables the further breakdown of the material by naturally-occurring micro-organisms. The first process of degradation in OXO-treated plastic is an oxidative chain scission that is catalyzed by metal salts leading to oxygenated (hydroxylated and carboxylated) shorter-chain molecules . OXO plastic, if discarded in the environment, will degrade to oxygenated low molecular weight chains (typically MW 5-10.000 amu) within 2–18 months depending on the material (resin, thickness, anti-oxidants, etc.) and the temperature and other factors in the environment. OXO plastics are designed so that they will not degrade deep in landfill and they will not therefore generate methane in anaerobic conditions, which is a powerful greenhouse gas. OXO-biodegradable products do not degrade immediately in an open environment because they are stabilized to give the product a useful service-life. They will nevertheless degrade and biodegrade in Nature if they are exposed to the environment as litter much quicker than natural waste such as twigs and straw and much more quickly than ordinary plastic. OXO-bio plastics will degrade indoors, but this is not their purpose. They are intended to degrade and biodegrade by a synergistic process in the open environment. OXO-biodegradation of polymer material has been studied in depth at the Technical Research Institute of Sweden and the Swedish University of Agricultural Sciences. A peer-reviewed report of the work was published in Vol 96 of the journal of Polymer Degradation & Stability (2011) at page 919-928. It shows 91% biodegradation in a soil environment within 24 months, when tested in accordance with ISO 17556. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Oxo Biodegradable」の詳細全文を読む スポンサード リンク
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