1. NF3 was originally used by the US government as an energy intensive oxidizer for rocket fuels. I believe it then migrated to being used as an F laser source gas for "Star Wars" applications, where it is still used today. Currently the major application is as a plasma cleaning gas...
There are many possible ways of improving the barrier properties of polyolefins, but it is a cost/performance issue. Judging from your being pushed out of PC due to cost, most "solutions" would also be too expensive; based on the feed materials, equipment and/or operations (labor)...
NF3/CF4 also form an azeotrope or pseudo-azeotropic mixture at cryogenic temperatures, one that is esential impossible to split without the use of a co-solvent/stripping agent like HCl.
Depending on the pumping system you are working with, there may be either an internal or external gas ballast system on the pump. With an internal ballast, the valving is often essentially check valves built into the pump that bleed some reject gas (from the high pressure side of the pump) back...
