Sustainable Solutions April 2009

RESEARCH
PLA: A green plastic?
Polymers in general - and plastics in particular - are generally viewed as convenient but seriously
environmentally damaging. Is crop-derived and chlorine-free polylactic acid (PLA) the ideal
replacement? Ruari McCallion considers the claims.
S
OME GREEN or sustainable rising tomorrow that Dow is not sincere," The facility in Blair, Nebraska, was using
initiatives or ideas may follow says Hind. "I've been involved in this ﬁ eld up to 40,000 bushels of corn each day in 2007
the dictates of fashion and for 30 years and it's generally recognised that and is capable of producing more than 300
rise or fall in popularity, there is a transformation process we have to million pounds of PLA each year.
depending upon science, practicalities, go through. You can forget 'green chemistry'. Applications include ﬁ bre for clothing and
beliefs or prejudices. But one thing remains Dow isn't involved with it. They are, however, a plastic for food packaging.
constant: concern about plastics. While there involved with a coalition that's seeking to roll In January 2005, Andrew N Liveris, Dow's
has been some improvement in reducing back legislation to a pre-1970 stage. They president and CEO, said: "Customers are not
their persistence in the environment - and reduce human life to cost-beneﬁ t analysis - an willing to pay a premium for environmentally
their recyclability - the sight of a plastic bag accounting standard." friendly polymers."
blowing down the beach can still provokes a One of the legislative measures that On the same day, Dow Chemicals pulled
shudder of revulsion. has been opposed is REACH, the EU's out of the PLA business when it sold its stake
Manufacturers of polymers claim to Registration, Evaluation and Authorisation in the joint venture to Cargill.
be working on improvements in recycling of Chemicals Directive. It overturns the One can shrug one's shoulders and say
and biodegrading, but their sincerity may 'grandfathering' principle - that compounds "that's business"; one can get outraged and rail
sometimes be open to debate. developed before implementation of previous against the iniquities of capitalism and its lack
Take Dow Chemicals, now the owners legislation in 1981 were assumed to be safe of environmental sensitivity. But one should
of Union Carbide (the Bhopal disaster and weren't subject to testing. The pre-1981 also look at PLA and examine whether it is
company). It has received several awards chemicals group includes such compounds the 'miracle' green plastic some proponents
and citations, including its Dow Corning as chlorine, dioxins, PVAs (polyvinyl would have you believe.
joint venture being named as one of the acetates) and PVCs; hardly 'safe', either in Polylactates are a class of biodegradable
most employee-friendly organisations by their production or their persistence in the polymers, which can be made from either
both Forbes magazine and the Great Places environment. However, the chlorine-based renewable or petroleum feedstocks. Cargill
to Work Institute and various others. It had plastics industry is well established and has been at the forefront of developing PLA.
a business conduct committee in place for proﬁ table; some companies - but by no means It has taken the renewable (as opposed to
decades, and a written code of business ethics all - seem to be as addicted to it as a junkie is petroleum) feedstock route, based on the
that looked ideal. to heroin. The talk may sound good, but as we fermentation of corn starch with lactobabillus
All very laudable, but some take issue. all know: actions speak louder than words. acidophilus.
"I was invited to brief international At the time Hind was brieﬁ ng Dow, it was In its rather clever process, intermediate
Dow executives at the time it was merging involved in a 50/50 joint venture with Cargill calcium lactate is reacted with a trialkyl
with Union Carbide," recalls Rick Hind, Inc, which produces and distributes crop amine and carbon dioxide, which produces
legislative director, Greenpeace Toxics nutrients and feed ingredients to farmers. amine lactate and regenerates calcium
Campaign. "I brought with me statements The joint venture, named NatureWorks, carbonate for reuse. Amine lactate, when
from the company's website, which listed produces a polylactic acid (PLA) polymer heated in hot water, decomposes to high
lofty goals." He told the meeting that, if from renewable sources. It doesn't use purity lactic acid and releases the amine for
those statements were to be taken seriously, chlorine and, in addition, generates lower reuse. This avoids the need for puriﬁ cation
then Dow would have to get out of chlorine emissions of greenhouse gases and virtually and eliminates calcium
chemistry - which includes PVC (polyvinyl no toxic chemicals during production.
chloride) and other plastics.
"I'm as certain as the sun
48 SUSTAINABLE SOLUTIONS April/May 2009
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