Question

A solid sample of an unknown plastic was insoluble in toluene, acetic acid, formic acid, as well as DMF and DMSO (not shown in Scheme 1). The plastic sank in an ethanol- water (4:1) solution but floated in an ethanol-water (10:7) solution. What is the most likely composition of the polymer?

Answer 1

One physical method of separating polymers is by density differences. The plastics to be recycled are shredded and placed into a liquid such as water. The plastics that are denser than water will sink, while those less dense than water will float. The floaters and sinkers are recovered separately, and the process is repeated with other liquids having different densities. This can be done on a small scale with readily available liquids.

Polymer

Density range / g cm-3

EPS - expanded polystryrene

0.02-0.06

PP - polypropylene

0.89-0.91

LDPE - low density polyethylene

0.91-0.93

HDPE - high density polyethylene

0.94-0.96

PS - polystryrene

1.04-1.11

PVC - polyvinyl chloride (PVC)

1.20-1.55

PET - polyethylene terephthalate

1.38-1.40

Now you can get answer. The given polymer will be PVC.