Issue Date: June 13, 2011
Plastics In Space Suits
“Saving Space Suits” by Sarah Everts was an interesting and fun piece, especially for the generation of us who watched Neil Armstrong on the moon in the wee hours of our morning on a black-and-white, low-quality TV (C&EN, May 9, page 40). However, I must question her knowledge of polymer chemistry.
Everts likens the migration of plasticizer from polyvinyl chloride to the leaching of bisphenol A from polycarbonates. PVC plasticizers swell and dissolve some of the polymer, and the other is free to migrate and evaporate (albeit quite slowly), making the article brittle. Fifty years ought to do it. The amount of plasticizer in the PVC tubing originally is measured in tens and twenties of percent. BPA in polycarbonates is unreacted monomer that is present in parts per million. Does it migrate or does it leach?
Good try at an analogy, but the mission fails.
I was surprised to read that “PVC’s dioctyl phthalate plasticizer tends to leach ... in much the same way that polycarbonate baby bottles leach their bisphenol A plasticizer into the contact liquid.” My impression was that BPA is the backbone of the polycarbonate molecule, not a plasticizer. Am I mistaken?
Will D. Merritt
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