Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Recycling Codes
Name: Nieslanik
Status: student
Age: N/A
Location: N/A
Country: N/A
Date: N/A 


Question:
I am a high school student studying recycling. I have noticed different numbers on the bottom of some plastics. Our town will only recycle those with a 1 or a 2. What is the difference between all these codes?



Replies:
The reason for the difference in codes is that there are different types of plastic. The codes are usually placed inside the recycling symbol, and the letter abbreviation for the type of plastic is usually placed underneath the symbol. You will find 6 codes corresponding to the following letter codes and types of plastic: 1: PETE, polyethyl tetraethylenei 2: HDPE, high density polyethylene; 3: V, vinyl (PVC?) (this one I am not certain of); 4: LDPE, low density polyethylene; 5: PP, polypropylene; 6: PS, polystyrene (found as plastic or foam). Your town is only equipped to recycle polyethylene (the density does not matter) so they only accept codes 2 and 4. Each type of plastic is a different chemical with different properties so they generally are not combined during recycling. PETA (1) is a tough, somewhat bendable plastic commonly found in 2 liter pop bottles. Polyethylene (2 ~ 4) is a good general purpose plastic. HDPE (2) is suitable for milk jugs, nonpressurized bottles and plastic cups. LDPE (4) is used to make "stretchy" type plastic for plastic wrap and bags such as those from Jewel (crinkly K-Mart bags are HDPE). (3) is a hard plastic that resists oils and petroleum distillates. Much of automotive products and oil based cleansers require the use of V. HDPE will eventually be attacked by certain chemicals that V will not. PP (5) is generally harder than HDPE, but tends to be brittle. It is the material found in sour cream and yogurt containers. PS is a plastic frequently used to make disposable cups. It is .used either in its plastic form, or made into foam. Polystyrene foam, a trademarked product, is a type of PS. Another reason your town does not except anything but 2 and 4 plastic for recycling is the typical contents of the containers. 2 and 4 are usually only accepted if they contained food products. Most communities do not want HDPE bottles that contained chemicals because the chemicals, if not completely washed out, may still be present in the recycled product (or ruin the process). 3 plastic, for example, is used in most household situations, to hold chemicals. By taking 2 and 4 plastic, the community gets a large percentage of the plastic suitable for recycling. For more specific information on your particular community, contact your local recycling center or a large recycling center such as the Lyons branch of BFI (708-442-1110).

Eric Dallman



Click here to return to the Environmental Science

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory