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Deforming Polylactic Acid (And playing with thermometer guns)

By moleculeoftheday on September 27, 2006.

Inspired by Keith's comment on polylactic acid's tendency to deform under heat, and procrastination, I just did a quickie test of the heat-deformation characteristics of my polylactic acid bottle.

I took my PLA bottle and a cute little PET bottle I had lying around. I put some tap-hot water in the microwave and heated it up for awhile. After stirring to equilibrate the temperature, I measured it with my oh-so-cool noncontact thermometer, a Raytek Raynger ST-6, which I wouldn't own if it weren't for Jeffrey Steingarten's unintentional salesmanship (fortunately, by the time I got one, the model was about as dated as a PDP-8, so I think mine cost a few percent of what he paid). It was 168F/76C, so hotter than you'd ever encounter in a car (and maybe enough to even bring the PET above its Tg). I added a couple hundred mLs of water to each.

I love this thermometer. I am less thrilled with my ability to use available light.

I could never be a photographer because I'm too impatient/unskilled to get decent "before" shots. Deformation started immediately after addition of water. This is T+30 seconds or so

Another after shot. PET held up fine, eh? Deformation under gravity pretty much stopped here but the PLA was still deformable with manual pressure. T+2 minutes.

Back to work. See you tomorrow.

Tags
Polymers

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