Acrylic is synthetic material with a wide range of possible end uses. Acrylic can be made into yarn or fabric as well as many other types of products.
In the book Textiles: Fiber to Fabric. The author, Dr. Bernard P. Corbman, explains that "basically, acrylic is a type of plastic."
The Federal Trade Commission defines acrylic in the following way:
"Acrylic. A manufactured fiber in which the fiber-forming substance is any long chain synthetic polymer composed of at least 85 percent by weight of acrylonitrile units."
Let's break that down into plain, understandable English, shall we?
A "manufactured fiber" is one that is not found naturally, but rather is man-made. (In contrast, wool or cotton would be examples of natural fibers; an acrylic yarn does not fall into that category, but rather is categorized with the synthetic yarns.)
The "fiber-forming substance" simply means the stuff the fiber is made out of.
A "long-chain synthetic polymer" – To my way of thinking, (and I'm not a chemist,) this is just a fancy way of saying "plastic." But for the last word on that, I'll refer you to Anne Helmenstine, PHD, your Guide to chemistry at About.com. Anne explains, in a nutshell, what a polymer is here: monomers and polymers. While you're reading her article, keep in mind that, as applied to acrylic specifically, by definition, the FTC specifies that this particular type of polymer is synthetic, not natural.
Acrylonitrile units – Acrylonitrile is a clear, toxic, water-soluble liquid chemical substance. According to the Environmental Protection Agency, acrylonitrile is probably carcinogenic, meaning that it probably causes cancer..
For further information about its chemical composition, I'll again refer you to the chemistry site at About.com: Acrylonitrile's chemical structure
So let's recap. Acrylic is, by definition, a man-made, synthetic fiber which is comprised of at least 85% acrylonitrile, which is a toxic chemical that the EPA warns is a probable cancer-causing substance.
Most of the yarn in my grandmother's stash is acrylic.
Kate is trying to decide whether to use acrylic or wool for crocheting her next hat.
References and External Links:
I used the following resources for reference when writing this article:
From the Federal Trade Commission's Website: The rules and regulations under the textile fiber products identification act
From the Environmental Protection Agency's Website: Acrylonitrile Hazard Summary 107-13-1 -- IRIS Toxicological Review of Acrylonitrile
From the Agency for Toxic Substances & Disease Registry Toxic Substances Portal: Acrylonitrile
J.J. Pizzuto's Fabric Science
Allen C. Cohen
Fairchild Publications, New York
Textiles: Fiber to Fabric
Dr. Bernard P. Corbman
McGraw-Hill Book Company