I am not sure about the PTFE, but on the top I have used UHMW Tape. It looks to be a little cheaper than the PTFE, but I can't speak to it's performance but as for the UHMW I have had it on the roof for about 8 years now without any issues.
UHMW (Ultra High Molecular Weight) polyethylene provides a slippery, high-slide, low-friction surface similar to PTFE tape but with higher abrasion and puncture resistance. UHMW tape is much tougher than PTFE and more economical. UHMW is ideal for chutes, liners, packaging lines, slides, and anywhere high-pressure sliding contact occurs. UHMW is great for sound dampening, it eliminates squeaks, rattles, and buzz caused by movement of adjacent parts. Temperature range is -40 to 225°F (-40 to 107°C). UHMW film is FDA compliant for food contact.
http://www.amazon.com/Cole-Parmer-Ul.../dp/B003NV022O