Monday, August 20, 2012

Cleaning Up the Lab

It's been a long summer with the intern, and for a while things were running faster than we could keep up. The exciting experiments outpaced the dull maintenance aspects of lab life. For reasons beyond our control, that pace has now lagged. Looking around, it looked like the morning after an all-night party. Flasks, beakers and jars everywhere. It was time to clean up.

Much as I would like to claim wisdom and foresight, it is rather the hard-and-painful knocks from experience that made sure everything was labeled, so it was easy to firmly decide on keep/toss for all the containers and samples, except for one flask.

It wasn't that the flask had an unknown sample in it - I knew exactly what is was - a sample of polypropylene crystals floating in tertralin (1,2,3,4-tetrahydronaphthalene). We had been extracting some material from it, and tetralin in a great solvent for dissolving PP as it is non-polar but has a sufficiently high boiling point to allow for the solvation of the PP. (There are no solvents that dissolve PP anywhere near room temperature. The heat of crystallization has put the sample so far down the thermodynamic well that only a tremendous amount of heat will be able to crank the windlass and raise it up.)

So we extracted what we want, and let the flask cool. As expected, the PP crystallized out and now floats in a thick layer near the top (PP has a density of about 1, while the tetralin has a density of 1.54.) So the question, still unanswered, in my head is this: is there still something we can learn from those crystals?

1 comment:

Materialist said...

Are you satisfied with the data on hand about how the flask cooled?
Sometimes a sample or experiment is maddeningly interesting, but the gathered data isn't enough/of the appropriate type to answer additional questions.
If it is useful as a prop, then it can be kept for that purpose. Otherwise, it is either a useful sample of PP/tetralin to compare against something in the future, or something like that alumni magazine you never know whether to throw out but end up thinking about/sorting multiple times until it is gone.