I have read conflicting forum posts as to whether acetone dissolves PLA or not, so I dropped a piece into a jar of acetone for an hour or so. The effect was truly bizarre:
It split into three strands a bit like peeling a banana. It was clear PLA but the acetone was polluted with ABS, which is why it turned white I think. Whereas it is normally transparent and brittle, it has become translucent soft and flexible. When I opened the jar it was under pressure so I think it evolved some gas.
So acetone doesn't dissolve PLA, but it appears to trifurcate it!
Not a very scientific experiment as I should have done it with pure acetone, but interesting never the less.