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How is your Mer Made?


This has something to do with The Shape of Water.

In the world of plastics there are a lot of big words used to describe some very small things.  At the really small level, long groups of atoms – mostly carbon and hydrogen – make up the fundamental building blocks of plastic molecules.  Essentially plastic molecules are nothing more than long chains of these two types of atoms – sometimes with a few extra bits thrown in, and sometimes not. 

At Horizon Plastics, we work with a class of materials known as thermoplastics.  These are materials that can be re-melted and re-shaped many times over – just by adding or removing heat energy.  Much in the same way as water can be turned back and forth between its solid (ice) and liquid states, so can thermoplastics. (So much for the Spoiler Alert!)

Take, for example, a typical molecule of polyethylene – one of the more commonly used thermoplastic materials.  Depending on the grade of polyethylene, it may have between 400 and 1000 atoms making up each molecular chain.  That seems like a lot, but each atom has a diameter that is only in the range of .00000001 inches (.000000025 cm) across.  If a human hair measures maybe .002 inches (.005 cm) in diameter, it would take 200 to 500 polyethylene molecules all lined up, end to end, just to span the width of the hair.

These long chain plastic molecules are made by a process called polymerization.  Although there are many different polymerization methods, their end products are always known as polymers.  Plastic molecules are all Polymers. 

Now the term Mer is often given to a group of atoms that is repeated in a single molecular chain.  A Monomer is one single Mer while a Polymer is the name given to many of the same type of Mers that are all connected one after the other.  So in the case of the polyethylene thermoplastic we looked at earlier, it is a polymer made by a process called polymerization and the main feedstock in the process is the monomer called ethylene.  The ethylene Mer is what ultimately gives polyethylene is characteristic performance as a plastic polymer. 

Taking it to the next level, some more terms come into play.  The prefix Homo which means “of the same” is part of the name for a type of thermoplastic known as a “Homopolymer.”  In a Homopolymer, the entire polymer is made from a single kind of Mer.  By contrast, if two or more kinds of Mers are used to make the polymer, it is known as a “Co-Polymer.”  Often you will find both ethylene and propylene Mers mixed into a wide range of thermoplastics – everything from Co-Polymer Polyethylene to Co-Polymer Propylene.  While main the difference between ethylene and propylene materials comes from the fact that the ethylene Mers have two carbon atoms in their structure, while the propylene Mers have three, the physical properties of polyethylene polymers are a lot different from those of polypropylene polymers.  Similarly the properties of homopolymers can be a very different than those of co-polymers.  And it can get even more confusing if you mix two or more different polymers (different molecules) together into plastics which become known as Alloys.

Don’t worry, if it gets too confusing, Horizon can help you select the right thermoplastic for your specific application.  With over 45 years of experience and we can help you through the decision process.  You may not know (or really care) how your Mer was made – but we do.  Horizon can provide you with a Mer Made to Order.