Fiberglas is in fact the trademark for just the glass fibers, not the composite, but the abuse by the public doesn't stop there. Styrofoam is (mis)used to refer to any foamed product made from polystyrene such as coffee cups and carryout food packaging, when in fact Styrofoam is Dow's trademark for expanded polystyrene used as insulation in the construction industry and in that application alone. And don't get me started about Mylar and Saran.
These are all examples where a company puts a lot of time and effort into building a brand name that is recognized for being a quality product only to then see competitors come in and ride the coattails. That hurts the brand owner's business and that is why lawyers spend so much time trying to prevent genericization of a brand.
But for polymers it can become quite a bit worse. That happens when the public makes a subtle change to a generic name by dropping the "poly-" prefix. The most prevalent example is polyurethane becoming urethane. Go to any hardware or paint store and look at how many "urethane" floor coatings there are. None of these coatings are made from "urethane" (ethyl carbamate) but are made of a polyurethane. Urethane is a white powder, completely inappropriate for a floor coating.
In this case, there is little or no harm done. But that can all change when polystyrene becomes shortened to styrene. The National Academy of Sciences just released its Report on Carcinogens and included "styrene" in the list. For people that don't understand the difference between polystyrene and styrene they can freak out. And somewhat deservedly so. No one wants a food container or coffee cup that is made up of a carcinogen.
But there are significant differences between styrene and polystyrene. Styrene is a sharp-smelling, liquid while polystyrene is a hard, brittle solid. You can boil styrene, but you can't boil polystyrene (it will just burn up when it gets too hot.) Most importantly, polystyrene is not a carcinogen, while styrene (the smelly liquid) is. And calling polystyrene as styrene doesn't change it into a carcinogen. While polystyrene is made from styrene (the smelly liquid), the chemical reaction that turns it into a polymer completely changes styrene's physical and chemical properties.
This trend of dropping the "poly-" prefix is likely not going to end well as other similar cases arise where people confuse a dangerous monomer with the polymer. Stopping this trend is nearly impossible as there is no one to defend these generic names other than industry wide organizations and even that would be challenging. Lawyers are going to have an extremely hard time convincing a judge that someone should cease and desist from using the word styrene to refer to polystyrene.
Where this all ends up is hard to see, but I don't think much good will come from all this polyprefixicide (to borrow and corrupt Don's word).