Monday, September 15, 2014

Plastics Scorecard v1.0 - I can't wait for v2.0

Being that I've spent my whole career working with plastics, I've had more than my fill of anti-plastic nonsense. But most of it is "harmless" statements about how bad plastic is. Statements such as "every piece of plastic ever made is still in existence" or any of a number of inane statements about "floating island of plastic in the ocean" or statements made by people thinking they are living a plastic-free life. When such statements are made by unprofessional individuals, I seldom get worked up or even respond.

But last Friday I ran across a new level of plasti-phobia that is so devoid of any technical support and yet, because of the graphics and table screams of respectability. It's all from this new "Plastics Scorecard v1.0" prepared by BizNGO. For reasons that are completely unclear, they have scored various plastics solely on the chemicals that are used in their preparation, or maybe more correctly, the chemicals that they think are used in their preparation. While that is a fair concern [1], focusing on just one aspect of a system is never a good idea and that applies in this case as well. So the fundamental logic of this scorecard is already incorrect. But what is really maddening is that the statements used in preparing this scorecard exhibit a new level of ignorance regarding chemical safety that I've seldom seen. Here are just a few examples of this. You can read the report and find more.

For instance, polyethylene terephthalate (PET) gets knocked heavily for its use of acetic acid in the preparation of terephthalic acid. Acetic acid? Yes, because the authors consider it toxic, even though the oral LD50 is about 3 g/kg. They are similarly upset about the use of ethylene glycol, even though its LD50 is higher yet at 5 g/kg.

The authors of this report have a very strange understanding of polymer chemistry. For instance, they are concerned about bis-(2-hydroxyethyl) terephthalate as an intermediate to PET, which it technically is [2], but it is never isolated in the process. Stranger yet is their understanding of the preparation of polylactic acid (PLA). They list glucose as the starting material rather than corn and they completely overlook the acids or enzymes used to hydrolyze the starch into glucose. No one makes PLA by starting with glucose, but rather from corn or some other source of a hydrolysable starch.

All of this shows a large shortcoming of this approach to scoring polymers: the starting point for a polymer is not always clear, and yet they are relying on the starting point to make their judgments.

The summary report is filled with howlers, such as "It is clear that manufacturers can make significant progress towards producing polymers from inherently safer chemicals" No, that is not clear in the least. What would these people consider inherently safer chemicals? Water? And where are is the carbon for the backbone to come from? Carbon dioxide? Coal? And similarly for hydrogen, what would that source be? Hydrogen gas? Prepared from what toxic chemical? And even the oxygen that is needed for making many polymers toxic to human in its pure gaseous form. That the highest scoring polymer was PLA and it only managed 58 out of 100 points shows just how ridiculous the entire scheme is.

While it is easy to write this off as the effort of just a few powerless individuals, the authorities that they have lined up supporting it is frightening, including Ken Geiser, professor emeritus, University of Massachusetts - Lowell and Helen Holder, Material Strategist, at HP amongst others. I have to seriously wonder if these people really read the report before signing onto the effort. I plan to contact them and let them know my opinions and challenge them on theirs.

[1] I've always had the willies thinking about phosgene being used to make polycarbonate (even though everyone is much more concerned about it's comonomer BPA).

[2] The initial condensation reaction yields water which limits the molecular weight that can be obtained. Using this intermediate "monomer" allows the polymerization to proceed without producing water.

Previous Years
September 15, 2011 - Follow Up on Yesterday's Post

September 15, 2010 - Purging

September 15, 2010 - A Strange Connection (if it even exists)

September 15, 2009 - Tires for the moon (and beyond)


milkshake said...

Rat oral LD50 of NaCl is 3g/kg

Anonymous said...
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Anonymous said...

You always have the option of running naked through the fields eating fruit to move away from the whole polymer issue