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High and Low Density Polyethylene

In a liquid of appropriate density, high density polyethylene sinks and low density polymer floats.

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.6 MB, 9 seconds

File: MOVIES/TRAM16/0561529.MOV

Voiceover
A sample of high density polyethylene and a sample of low density polyethylene separate according to their densities.

Discussion
A sample of high density polyethylene cut in the shape of an "H" and low density polyethylene cut in the shape of an "L" are dropped into a cylinder containing a 1:1 mixture of ethanol and water. The high density polyethylene sinks and the low density polymer floats.

High density polyethylene is a linear polymer that has crystalline regions and is used to make rigid containers such as 1 gallon milk bottles. Low density polyethylene is a branched polymer whose molecules pack more loosely than those of high density polyethylene. Low density polyethylene is more transparent and waxy than the high density polymer and it is used to make flexible bottles and plastic wrap.


Citations:  
  Kolb, K. E.; Kolb, D. K. J. Chem. Educ. 1986, 63, p 417.
  Kolb, K. E.; Kolb, D. K. J. Chem. Educ. 1991, 68, p 348.
Design, Text and Demonstrator:  
  Gary Trammell University of Illinois at Springfield, Springfield, IL 62794
Videographer/Editor:  
  Steve Dykema University of Illinois at Springfield, Springfield, IL 62794
Voice:  
  Margaret Biddle University of Wisconsin - Madison, Madison, WI 53706
Audio Production:  
  Greg Minix University of Wisconsin - Madison, College of Engineering, Madison, WI 53706
  Jerrold J. Jacobsen University of Wisconsin - Madison, Madison, WI 53706