Brentwood Plastics blog

Homopolymers, Copolymers and Terpolymers - easy as 1, 2, 3

Posted by Joel Longstreth on Tue, Mar 31, 2015 @ 05:33 PM

The terms homopolymer, copolymer and terpolymer may sound like Latin or Greek.  They mean respectively 1,2, or 3 polymers.  This is sort of a misnomer as they are more like MONOmer building blocks conjoined through a reaction. 

Let's start with "polymer".  " Poly " comes from the Greek word for many.  As it pertains to plastic, it means many of the building blocks of monomers such as ethylene, propylene, styrene, etc. strung together in long chains to add up to polymers.

For more in-depth, visit our post on "where does plastic come from ? "

If the polymer is made simply from only one monomer, it is called a HOMOpolymer, or made from only one monomer.  POLYethylene, POLYpropylene, POLYstyrene, etc.  Far as I can tell, 1,2 Syndioatctic Polybutadiene is a homopolymer even thought the word is long.  Butadiene is the only monomer.

You guessed it - if there is another conjoined monomer ( not a mechanical blend ), you got a COpolymer.  Examples:  "ethylene vinyl acetate" or EVA for short - vinyl acetate monomer married to ethylene monomer, "styrene butadiene styrene" or SBS - styrene and butadiene building blocks,

A very cool copolyester is Eastman's Tritan.  Why it has not replaced glass on a major scale I do not understand.  I have some 5 year old tumblers which look like new.

And a TERpolymer is three monomers.  An oldie-but-goodie example is old fashioned phones which were made from "acrylonitrile butadiene styrene" or ABS.  Jump cut to present day - ABS is the default choice for 3 D printing.
A ubiquitous example of ABS is fake fingernails.



oldphone.jpgphoto courtesy of The Cathedral of Junk in Austin, TX

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Topics: polymers, plastic, copolymer, homopolymer, polymer, terpolymer

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