I wonder if the plastic differences could retard the rate of the electrons going back to their natural state and prolong the glow
The life of electrons in an excited state is a property of the material. The only way to get them to glow longer without implanting mild radioactive materials would be to eliminate all external stimulants. So if you want your discs to glow longer, don't throw them. Also, glow discs work better in colder weather as heat is a form of radiation. Even at night there are many sources of radiation. If something is not either absorbing or reflecting light (i.e. radiation), you can't see it (why outerspace is black).