How do metalloids, cermets and metal matrix composites reflect light?

AFAIK, “Teflon:” without modifiers is just PTFE. Non-PTFE “Teflon” and filled TEflons have extra letters after the name, like TEFLON-AF or TEFLON-FEP.

I don’t know how crystalline PCTFE is. As I say, how transpasr5ent it is depends upon its processing. It could be that the transparent stuff is highly crystalline.

http://www2.dupont.com/Teflon_Industrial/en_US/assets/downloads/k15758.pdf

Here’s duPont literature for Teflon perfluoroalkoxy resin (PFA), no PTFE at all. The trademark is for a line of fluropolymers. Yes, they also sell filled PTFE under that trademark, too.