Attempting to Eliminate Oil from Melted Plastic Products
Aarti Anand, Carly Dooley, Kathleen Thurmes
December 10, 2009 8:05 – 9:17 PM
Civil Engineering Building, Room 742
Introduction and Objective
We intend to investigate the leaching of oil out of the melted plastic we produce. There are
several reasons the oil could be present in the plastic after melting, and we will attempt to
address each possible reason:
A) The oil leaks out of the plastic immediately after melting, and so the leaching can be
stopped by simple removal (wiping or rinsing) directly after it is removed from the oil.
B) The leaching is caused by contraction of the plastic during cooling, which essentially
pushes the oil out of the plastic and to the surface. This can be determined by dousing the
melted plastic in a cold bath immediately following its removal from the oil.
C) Flour can be used after cooling to cover up the sliminess of the plastic.
Materials
 Roundy’s all-natural vegetable oil
 HDPE plastic chips from milk cartons
 2 Melting cups of ambiguous silver metal material
 Hot plate
 Spoon
 Stirring knife
 Metal tray for molding
Procedure and Observations
Part A: Wipe the plastic with a rag right after melting.
We used about half a cup of oil and heated it on a hot plate at a heat setting of 3 out of 12 in a
fume hood. After about ten minutes of heating the oil on setting 3, we inserted about 1/8 cup of
plastic chips. Ten minutes at setting 3 was not long enough to get the oil hot and the plastic
wasn’t melting, so we increased the heat to 11 out of 12. After about three to five minutes, the
plastic chips started melting/ fusing together (8:25). After about a minute, the plastic started to
turn clear. It didn’t stick to the sides of the vessel, however, even when pushed against them.
When the plastic was clear all the way through, it had reached its malleable state. We removed
the plastic mass at 8:29. The oil smelled as though it had been heated to fry something, but there
was no smell of burning and nothing dark in the oil itself; the oil, in fact, did not appear to be
dirty, contaminated, or toxic at all. We molded the plastic with a spoon and immediately wiped
the piece with a rag to rid it of oil. This did not rid the plastic of oil – the piece was as slimy/oily
as ever. There were no bubbles in the plastic.
Part B: Douse the plastic immediately in a cold bath.
We started on a heat setting of 5 out of 12 at 00:00:00 (we timed this trial) with a little over half
a cup of vegetable oil. We let the oil heat for 12 minutes. We then put in about 1/8 cup of plastic
chips, once again. We increased the heat setting to 7 out of 12, then soon increased the heat to 11
out of 12, because the oil was not being heated and the plastic was not melting. Finally, we
removed the plastic heap (00:28:32) and put it almost immediately into a cold bath. The water
was not very cold however, due to lack of ice in the lab. At 00:30:35 we took the plastic out of
the water. The water was a little cloudy from the oil, but the plastic was still very oil from
heating. The oil used to melt the plastic itself was very clear still – there appeared to be no junk
in it except for a few stray pieces of un-melted plastic shards. Once again, the plastic was giving
off the cooked oil smell after removal, suggesting that it was still seeped through with oil. Some
oil rose to the surface of the water, but not all the oil from the plastic piece was released in the
water, so it was a very thin layer of oil floating on the surface.
Part C: Use flour on the slimy piece from Part A.
We covered the slimy piece from part A with flour at 8:44 by putting flour in a beaker and
dropping the piece in then shaking. We then scooped up flour – after leaving the piece in the
beaker for about thirty seconds – and pressed it to the plastic in parts where the flour had not yet
adhered. Then at 8:46 we rinsed the piece off with water and dried it; it was still sticky. We put
the piece back in the flour, then, and let it sit for 33 minutes. It still appeared to be just a slimy
piece of plastic with flour on it.
Conclusions
Disposal of waste and other experiment materials: We left our labeled samples in the lab room.
The oil waste was taken back to the EWB room to be added to the “toxic sludge” waste bucket.
The oil water was disposed of down the drain.
None of the methods we used here were successful in either stopping the oil leaching or covering
it up. However, we only used vegetable oil and HDPE plastic; perhaps our results would be
different if we used a different melting medium and/or a different type of plastic.