At the California State University at Chico, Joe Greene has been examining the potential for bioplastics to reduce the effects of debris in the ocean. The US has a good system for large waste cleanup along the shore line, which means that the main contaminant is smoking-related materials like cigarette butts (35%), plastic bags (6%), food wrappers (10%) and plastic bottles (5%). The ASTM standard D6691 is a test used to simulate degradation in ocean waters – a Mirel carrier bag showed 70% disintegration after 12 weeks in this test, and Mirel PHA behaved like cellulose in marine water under ASTM D7081. The university has been trying to blow mold biodegradable bottles with only limited success.
Mirel is a trade name of the Telles company and is a PHA made by fermenting corn sugar. The production facility in Iowa has a production capacity of 50,000 tons per year. There are grades for injection molding, sheet, film, thermoforming, coating, foam and fiber.
Novamont is the producer of Mater-Bi polymer and is owned by the largest merchant bank in Italy, Banca Intesa-Sanpaolo. The biorefinery has capacity of 80,000 tons per year. This biodegradable plastic is used in films including agricultural mulch and although it has a high water vapor transmission rate (WVTR), it can be treated to improve this.
PLA can be biaxially-oriented in films using technology similar to that used for polypropylene (BOPP). One of the companies leading this new industry is Toray Plastics. The BOPLA is said to have good mechanical properties lying between those of OPP and PET and can be used as a print web or seal web. The metallized PLA can be used as a foil or to replace other metallized films according to Toray Plastics. The film has moderate oxygen and moisture transmission rates and should be converted at temperatures below 180F.
The technology for processing these new bio-sourced plastics is advancing. Reifenhauser has worked on film and sheet extrusion equipment for cellulose, starch, PLA and PHA materials.
As one example, the major use it has seen for PLA is in extruded sheet for thermoforming. The PLA should be pre-dried prior to extrusion and it is important to avoid sag using various adjustments such as a duck-bill die design to minimise the gap between the die exit and the primary roll.
As consumers look to a “green agenda” it is important to give accurate information about products. Companies such as Beta Analytic quantify the biobased content of materials using ASTM D6866 methods by measuring the carbon-14 content.
The test result is given as a percentage of renewably sourced carbon compared to the total organic carbon. Carbon-14 is formed from nitrogen-14 reacting with cosmic neutrons in the atmosphere and it undergoes radioactive decay with a half-life of 5730 years.
This is taken up by plants and incorporated into biomass. Due to the decay rate there is no carbon-14 in fossil fuels. Hence, the carbon-14 levels indicate the biobased content of a material, which can be listed on the USDA BioPreferred voluntary labelling program.
What about waste disposal of biodegradable plastics?
Organic Waste Systems, Inc. designs and constructs anaerobic digestion plants for organics and is involved in compostability certification and standards in the USA and Europe. Composting takes place in stages: biodegradation at a chemical level, followed by disintegration at a physical level.
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sent: 2012-02-12 10:24:02 Freecycle.org. Pretty sure Wellington now has a group. One pseron’s trash is another pseron’s treasure. |
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sent: 2012-03-12 22:08:18 Crunchy,As long as cigarette feltirs will not count as hazards to wild and domestic animals, I doubt ocean plastic dumping will raise much fuss.My thinking is that tobacco companies got caught lying about the dangers of smoke, of second hand smoke, of third hand smoke residue (residue deposited by cigarette smoke in vehicles, rooms, and on clothes that later causes bad effects). So now the 'conversation' is over. Those discarded cardboard and foil packages, the filter parts (containing residues of the cigarette as well as their chemical composition -- I don't see 'biodegradable' used to describe feltirs any time recently -- or non-toxic after use, either).I am completely sold on the notion that recycling is dangerous to America and the world - it burns tax dollars and oil. Even the recycling that is shipped to Mexico 'cause they don't have our EPA banning the processing.Recycling, by it's presence, gives permission to those making plastic stuff and those choosing plastics.And yet, there is the plastic cereal box liner -- when was the last time you got a box of corn flakes with bugs going wild? Zip-loc bags - each, when new, is sanitary.If not for plastic buckets - would that mean lots of metal buckets, with the cost in energy to mine, refine, manufacture, and transport the metal and metal products? I am thinking of the massive use of plastic 55 gallon barrels for oil products, for lead detector solution, etc. Paint buckets for the big jobs, in five gallon buckets.Aluminum was once called 'solid electricity', from the practice of building a hydroelectric generator/dam near a bauxite (aluminum ore) mine, to smelt the aluminum on-site.I remember years ago the angst over how much more energy a can with a pop-top took to make than a simple can that you used a can opener to puncture. It seems that conversation diet. But now, look at the number of two-liter soda and half-liter water bottles are churned out. Or disposable juice six-packs and eight-packs. With a market place seemingly addicted to plastic bottles - what is the alternative? The old 48 ounce juice cans can still be found, sometimes. How many people today have ever bought one? When single-serving frozen meals (TV dinners for us old-timers) moved from the oven to the microwave, they moved from aluminum foil to plastic - with plastic film tops.Is waxed paper still made with petroleum/plastic coating or paraffin, or still real wax? I doubt the wax part. And, again, how many homemakers have ever wrapped a lunch sandwich in waxed paper -- that was still 'sealed' when opened?I am not disputing that reducing plastic use is essential. What I don't see is a path forward.Using glass in the microwave works well. Also ceramic. But that pretty much eliminates the reduction of spoilage from single serving packaging. And also contradicts the single-serving lifestyle so many families seem addicted to (and the only heritage their children will realize).It seems that in order to diminish relying on plastics, you have to first dismantle the current lifestyle of endless ambition, and the corporate-like rush to efficiency.And stop recycling. It is 'false efficiency'.@ Beth Terry,I find the 'pure cornstarch' baby powder works pretty good. |
