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Plastics—?
Posted at: 2009-10-02 11:18:09
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There’s a dedicated green-plastics website here. Looks very good but I haven’t had the chance to look at it yet http://www.greenplastics.com/reference/index.php?title=Main_Page |
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Plastics—?
Posted at: 2009-10-02 11:16:17
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In terms of bio-degradable plastic, people are trying to develop plastics that break down completely with exposure to sunlight, wind, bacteria, enzymes, water, insects, etc. Starch powder is sometimes put in plastics to make it break down more easily, but it doesn’t make the plastic break down completely.
There’s a thing called Biopol which uses genetically engineered bacteria to synthesise a completely biodegradable plastic. Imperial Chemical Industries developed it as far back as the 1980s but abandoned it, and someone else bought the patent. en.wikipedia.org/wiki/Biopol
Also there’s a thing called Ecoflex, a polyester which is completely biodegradable, used for food packing.
Bioplastics are made from biomass- either bio-petroleum or pea-starch film. And there’s Oxo-biodegradable plastic- polyolefin plastic with metal salts added. These (combined with Oxygen) speed up the degradation process.
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Plastics—?
Posted at: 2009-10-02 11:05:07
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This is from Wiki- the classification system you’ll see on plastic bottles and what it means. On the bottle, each number will be encircled by three arrows in the shape of a triangle.
1. PET (PETE), polyethylene terephthalate: Commonly found on 2-liter soft drink bottles, water bottles, cooking oil bottles, peanut butter jars.
2. HDPE, high-density polyethylene: Commonly found on detergent bottles, milk jugs.
3. PVC, polyvinyl chloride: Commonly found on plastic pipes, outdoor furniture, siding, floor tiles, shower curtains, clamshell packaging.
4. LDPE, low-density polyethylene: Commonly found on dry-cleaning bags, produce bags, trash can liners, and food storage containers.
5. PP, polypropylene: Commonly found on bottle caps, drinking straws, yogurt containers.
6. PS, polystyrene: Commonly found on ”packing peanuts”, cups, plastic tableware, meat trays, take-away food clamshell containers
7. OTHER, other: This plastic category, as its name of ”other” implies, is any plastic other than the named #1–#6, Commonly found on certain kinds of food containers, Tupperware, and Nalgene bottles.
en.wikipedia.org/wiki/Resin_identification_code
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Plastics—?
Posted at: 2009-10-02 11:01:37
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Well basically plastics are synthetic materials, usually inorganic. They don’t break down easily because of the molecule size and structure, which is good when they’re used for industrial applications, but not good when you consider their lifespan post-use and the way that they clog up landfill.
Toxicity is a different issue, and different plastics have different concerns about the leakage of dangerous chemicals- any chemicals that leak from plastic have generally been put there as an additive in the creation process, so I understand, as the plastics themselves don’t originally have such chemicals. Most plastics can be passed through the human digestive system with no ill effects other than those caused by obstruction and physical damage (correct me if I’m wrong). PVC has vinyl chloride which is recognised as a carcinogen. And monomers used to make a plastic product might become trapped in the product. BPA is a cause for concern- bisphenol A- this can ’leach’ into food from the lining of tin cans, polycarbonate bottles and dental sealants, Wiki describes it as an oestrogen-like ’hormone disrupter’, and can lead to insulin resistance, and therefore heart disease, and has also led to increase weight in laboratory animals (en.wikipedia.org/wiki/Plastic).
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