Magnetic tape composition
Primo, page 6 of the following link gives a run down on what magnetic tape is made of:
http://www.tape-online.net/docs/audi...o_carriers.pdf
As you can see, it's actually a fairly complex product. I imagine this would present a challenge wrt recycling. Plastics recyclers (not collectors like us, but those that actually process plastics into a finished product) might be a place to start. Either that or the companies that produce magnetic tape.
If your research turns up anything interesting, please post it.