Plastics Analysis Lab
Student Name:
Flow Chart
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Water
Test
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Sinks
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Floats | ||||||||||
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Copper
Wire Test
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Isopropyl
Alcohol Test
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Acetone
Test
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Oil
Test
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Heat
Test
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Reaction
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Density
Table
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Substance
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Density
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| Water | 1.00 |
| (1) PET | 1.38-1.39 |
| (2) HDPE | 0.95-0.97 |
| (3) PVC | 1.16-1.35 |
| (4) LDPE | 0.92-0.94 |
| (5) PP | 0.90-0.91 |
| (6) PS | 1.05-1.07 |
Purpose:
To identify the six kinds of recycled plastic resins by measuring their physical and chemical properties.
Background:
The plastics industry uses resin pellets to make plastic containers. Each of the recycled resins is color-coded to help you keep them separate in this analysis, but each may be made in any color. These resin samples have come from recycled products.
Materials:
6 samples of resin
pellets
250 mL beakers
100 mL beaker
Bunsen burners
or alcohol burners
forceps, tongs,
and plastic spoons
1 hot plate
stirring rods
or Popsicle sticks
copper wires
(5 cm, 20 gauge)
50 mL acetone
60 g isopropyl
alcohol (70%)
goggles
glass petri
dish
100 mL corn
oil
small cups
to hold resin samples
Procedure:
1. Notice the test areas in the room. Some tests are to be done only at those locations, while others will be performed at your lab desk. There are four specific test areas in the room that your teacher has set up:
a. Acetone Test—Have 50 mL of acetone in a 100 mL beaker covered with a glass petri dish. KEEP THIS TEST AREA AWAY FROM FLAMES. Acetone is highly flammable and must be kept away from flames and covered when not in use. Have tongs or forceps available.
b. Heat Test—Have 125 mL water in a 250 mL beaker on a hot plate. Keep this at a rolling boil. Have tongs available. Make sure this does not boil dry!
c. Isopropyl Alcohol Test—Put 60 g (or 65 mL) isopropyl rubbing alcohol (70%) in a 250 mL beaker and add enough water to make 100 g (or 100 mL) of solution. Mix. Have tongs or forceps available. Have plastic spoons available.
d. Oil Test—Put 100 mL of corn oil in a 250 mL beaker. Have tongs or forceps available. Have plastic spoons available.
The other two tests, water and copper wire, are to be done at your lab station.
2. You and your lab partner are given six different kinds of recycled resins. You should have about 10 pellets of each resin or color. Use the flow chart below and the descriptions of the tests to identify the resins. Keep notes of your observations on the sheet provided.
The following resins are the six you need to identify:
1. PET—polyethylene
terephthalate
2. HDPE—high
density polyethylene
3. PVC—polyvinyl
chloride
4. LDPE—low
density polyethylene
5. PP—polypropylene
6.
PS—polystyrene
Water Test
At your lab desk, place one pellet of each of the recycled resin samples in 100 mL of tap water at room temperature in a 250 mL beaker. Poke the pieces with a glass stirring rod to knock off any adhering bubbles and try to make them sink. Note whether the sample floats or sinks. Do not pour the resin samples down the sink — they are insoluble in water! Take the resin pellets out of the water with your fingers and save the pellets for later. Use the Density Table on the previous page to find the density ranges for each type of plastic. Proceed down the flow chart, do the tests indicated, and record all your observations on the sheet provided.
Copper Wire Test
At your lab desk, using forceps, hold the 5 cm length of copper wire in the hot part of the flame of a Bunsen burner or alcohol burner until it is red hot. Remove from the flame and carefully touch a resin pellet with the hot wire. It may stick to the wire at this point so you will need to take another pair of forceps to pull the pellet off the wire. Place the wire with some plastic glob on it (not the pellet) back in the flame, observing the color of the flame that comes from the glob. You will notice a green or orange flame color. Quench the sample in a beaker of water to stop the burning and cool the wire. Proceed down the flow chart.
Acetone Test
Take your sample resin to the acetone test area in the room. Using tongs, place a pellet in acetone for 20 seconds. Remove the pellet and press firmly between your fingers. The polymer chains may "loosen up" and feel soft and sticky. Try to scrape off some plastic with your fingernail. There may be no reaction to this scrape test. Discard the pellet in a container provided. (Note: If you are using fingernail polish remover instead of acetone, leave the resin pellet in for at least one minute. Use your fingernail to try to scrape the pellet to see if the outer layer has softened.) Place the used resin pellet in the special container for waste. Proceed down the flow chart.
Heat Test
Take your sample resin to the heat test area. Using tongs, hold one pellet in boiling water for 30 seconds. PET (1) has a relatively low softening point and will show some reaction to the 100 degree Celsius water. Press the pellet between your fingers to see if it feels softened after you remove it from the water. Discard the pellet in the trash can. Proceed down the flow chart.
Isopropyl Alcohol Test
Take five resin pellets to the isopropyl alcohol test area. Place the pellets in the solution and poke the pellets with a stirring rod to release any bubbles. Note whether the pellets float or sink. Scoop the pellets out with a plastic spoon and take the pellets back to your lab station. Proceed down the flow chart.
Oil Test
Take five resin pellets to the oil test area. Place them in the oil and poke the pellets with a stirring rod to release any bubbles. Note whether the pellets float or sink. Identify the resin from the flow chart. Scoop the pellets out with a plastic spoon and wipe them off with a paper towel. Take the pellets back to your lab station.
Clean Up
Please recycle your resins in the appropriate containers. Try not to mix the resins.