Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page Visit Our Archives Ask A Question How To Ask A Question Question of the Week NEWTON Teachers Our Expert Scientists Volunteer at NEWTON! Referencing NEWTON Frequently Asked Questions About Ask A Scientist About NEWTON Education At Argonne Alcohol and Plastic Interactions

Name: Sabine
Status: student
Grade: 9-12
Country: Belgium
Date: Spring 2013


Question:
In the archive I found a subject called "Amyl versus Isopropyl Alcohol" and I have a question about the last answer. It says: Neither of these alcohols "dries out" plastic, since there is no water (or any other substance) in plastic to "dry out" in the first place. But on other sites I found that Isopropyl alcohol could extract plasticizers out of plastics, which causes the plastic to craze or stiffen. Is this correct? Please clarify.



Replies:
Hi Sabine,

Very good question! It is true that alcohols can dissolve out (or extract) plasticizers in those plastics that contain plasticizers. But of all the commonly used plastics, the only type that contains plasticizers is vinyl. All other types including all polyolefins (polyethylene, polypropylene), polystyrene, ABS, polycarbonate, polyester, melamine, thermoplastic elastomers, and many more, contain no plasticizers, and thus are not subject to plasticizer leaching.

So, yes, exposure to solvents like alcohols can eventually case hardening and cracking of vinyl parts that were once flexible, but none of the other common plastics suffer this problem.

Regards,

Bob Wilson



Plasticizers are usually small molecules such as phthalate esters, providing softness and flexibility of plastics by separating polymer chains and lowering interactions between them. They are soluble in organic solvents such as isopropyl alcohol, and once they are removed from plastics polymer chains have stronger interactions between them to be stiff. Or after plasticizers are extracted from plastics, they leave void spaces and cracks which will become easy to break.

Weon-kyu Koh


In principle, any solvent that dissolves a plasticizer could extract it from a polymer. That would normally require prolonged contact, because the plasticized would have to diffuse out of the plastic, and diffusion is a slow process.

Richard E. Barrans Jr., Ph.D., M.Ed. Department of Physics and Astronomy University of Wyoming




Thanks for the question. The plasticizers in a plastic make the material flexible and reduce the hardness and brittle characteristics of pure plastic. Amyl alcohol and isopropyl alcohol are two of the many liquids which can extract plasticizers out of a plastic. In fact, you will find that cream of broccoli soup (tasty!) will extract plasticizers from a plastic bag (if you store the soup in the bag).

I hope this helps. Please let me know if you have more questions. Thanks Jeff Grell


Click here to return to the Material Science Archives

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 223
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: November 2011
Weclome To Newton

Argonne National Laboratory