Biopolymer Supply Chains To Reduce Toxic Exposures
by John Laumer, Philadelphia on 06. 3.06
In response to Lloyd’s recent post on toxins in plastics, a commenter remarked “I too look forward to some solutions”. Challenge accepted; we’re all on the trail. Lloyd followed up right away with some good rules of thumb . Now here's what we're talking about. From the distance, closer by the day, comes the sound of the Biopolymer Calvalry, charging down the supply chain to offer biodegradable water bottles made of polylactic acid, a.k.a. “PLA” or “corn plastic”. Once the supply chain is set up with the right raw materials (PLA), the necessary tools (like Norland's blow molding equipment offerings to the bottling industry, shown below the fold), and consumer recognition, solutions will proliferate for many applications.
Paraphrased from the PRLEAP press release: ’ Norland introduces the first small-bottle blow molders capable of producing bottles for bottled water or other uses from corn-based plastics (PLA) for use by small to medium-sized bottling operations. The compostible bottles are produced by using pre-forms made of PLA, a 100% corn-based plastic developed by NatureWorksLLC , a wholly-owned Cargill company, in Minnetonka, Minnesota'.
Readers please note: TreeHugger’s Kyeann Sayer’s excellent post on the pictured Biota product is worth reading to see the full life cycle context for PLA-based bottles and other single use plastic items.
Per the Kayeann and Lloyd posts, reducing toxic exposures by switching to PLA biopolymers offers a “tentative” win-win-win for the environment (toxic exposure reduction, biodegradability, reduced petroleum consumption). We qualify with a “tentative” because we do not have complete knowledge of the hazards of plastic additives that may be used in this and other PLA applications. Additives may range from fire retardants, to softeners, to anti-oxidants, to impact modifiers, depending on the application. But, we can be reasonably certain that none of the RoHS-banned substances, especially the brominated fire retardant, will be present.
More from the release: “The Norland blow molders, designed originally for blowing PET (petroleum-based) plastics, have been specifically adapted to handle the PLA plastics. Preforms made of PET and PLA have different characteristics. For PET, preforms must be preheated to 100-C, while PLA preforms must be heated to just 75-C”.
The reduced molding temperature requirement demands our attention. We've all heard the debates about the relative fuel efficiency of growing corn for production of fuel compared to just gasoline. When it comes to PLA blow molded products, yes we see that growing corn takes fossil fuel and that energy savings at the basic raw material level may not be that great. But, further down the supply chain, energy savings start to accumulate at point where monomer is made into polymer (plastic). Further energy savings accumulate when you account for the fact that spent bottles can be simply composted instead of being re-ground into a techical "food" for chemical recycling or "down-cycling. Now back to the release:
“PLA bottles offer a significant advantage to producers of bottled water, juices, oils and other liquid products—they are environmentally friendly. While it is estimated that petroleum-based plastic products require thousands of years to decompose, PLA products are compostible within 45-90 days. This compost material can then be used to fertilize the next year’s crop of corn, completing the cycle of a totally renewable resource. PLA plastics contain no petroleum, and require 20-50% less fossil fuel to create than PET plastics”.
For those of you wondering whether biopolmers can ever make it into high performance equipment applications like bicycles, roller-blades, snow boarding boots, and climbing equipment, the answer is "yes". Because TreeHugger is not the place for technical epics, we'll hold off for now on the details. But here are a few hints for you Google divers: -- Not PLA; Castor Beans; Athletes Foot; and Air Brakes. If anyone guesses the exact biopolymer we're hinting at we'll do a full post.
This sounds great for addressing the front end environmental issues. My only concern is on the back end - that consumers will mix up this PLA packaging with regular petro-plastic bottles in their recycling bins. Introducing PLA into that process would be a nightmare for recycling facilities (the ones that actually recycle, not the ones that just do the sorting) by contaminating the material stream.
I'm lucky enough to live in a city that picks up our compostables weekly - what will people do with these bottles if they neither do their own composting nor have access to city pick-up of their compostables? This stuff may be compostable, but it won't degrade in a landfill without oxygen and light.
The manufacturers should put bold identifiers on the bottles so that consumers and recyclables sorting facilities know to handle these bottles differently.
But what catalyst is used?????
Last time I looked into PLA a catalyst was used and this was normally a mined metal and I couldn't find out whether these catalysts were reusable.
=== author's response follows ====
I'm fairly sure that the exact catalyst composition would still be a trade secret. Typically the catalyst mass is so small as to be trivial --- a few hundreds of a weight percent -- so that re-use is not an issue. There is also likely to be an organic peroxide used as a "promoter" of the the polymerization reaction.
okay i give.
whats the biopolymer you're teasing us with?
=== author's response follows ===
Nylon 11, invented by German chemists during WWII era to cope with oil shortages, is a very commercially successful, high performance biopolymer made from Castor Bean oil as a raw material. One of the byproducts of N11 production is a fungicide used to control atheletes foot. Those colored air brake hoses one sees on big rig trucks are generally made from it, as are roller blades and other high performance sports equipment.