Working in the plastic sheeting industry, you’ll hear a variety of terms used to describe acrylic sheet, including plexiglass and Plexiglas®. Not knowing the difference between the terms can pose problems and confusion when it comes to shopping for the acrylic sheeting you need.
Plexiglass: The Generic Trademark
These two terms are pronounced the same, spelled almost identically, and can be compared to the relationship of tissue and Kleenex. These are known as proprietary eponyms, meaning a trade name has become the generic name for a product or service. Sometimes these are referred to as generic trademarks. What makes it particularly difficult to know the difference between plexiglass and Plexiglas® is the small variation in spelling. The difference in one letter stumps many people. Plexiglass with two s’s is the generic term synonymous with acrylic sheet. Plexiglas® with one s is the brand name. Other trade names that have become comparable to Plexiglas® include Acrylite®, Lucite®, and Perspex®.
So what came first? Plexiglass or Plexiglas®?
That depends on how you look at it. The chemical that makes up this thermoplastic, polymethyl methacrylate (PMMA), was invented in the early 1900s by Otto Rohm, founder of Rohm and Haas. Rohm was trying to increase the resistance of glass by creating a lamination between glass plates when he created a completely new material, acrylic. There were a variety of PMMA products available on the market such as Plexigum™ before the product we call Plexiglas® was produced. In 1932, Rohm produced the first PMMA cast sheet and in 1933, he produced a stable, transparent, hard, shatterproof polymer, which they registered under the Plexiglas® trademark. Plexiglass itself was created before the registered name of Plexiglas® came about, however, the name plexiglass did not appear until years after Plexiglas® dominated the glass and plastics industries.
Plexiglas® vs. Other Acrylic Sheeting
So if plexiglass is a generic trademark for Plexiglas®, which is an acrylic sheet product, does that mean Plexiglas® is the same as all other acrylic products? The short answer to this is, no, however, some acrylic products referred to as plexiglass will have the qualities the name brand has. The biggest difference between Plexiglas® and some traditional acrylic is the way they are manufactured. Acrylic can be manufactured one of two ways: extruded or cell cast. Plexiglas®, however, is manufactured in cell cast only. That is the biggest benefit to purchasing Plexiglas® over other brands of acrylic sheeting. Cell cast acrylic is more expensive to manufacture but is harder than extruded acrylic so it is less susceptible to scratching. Additionally, cell cast acrylic typically has fewer impurities such as ripples or specks.
In layman’s terms, Plexiglas® is made from acrylic, and plexiglass is a generic term used interchangeably to describe both the name brand and the material itself. Knowing the history behind Plexiglas®, as well as the differences between Plexiglas®, plexiglass, acrylic sheet should help you in your plastics projects in the future.