It would depend on the type of epoxy you are using. If it were a water based system, I doubt it would have any effect. If it were a solvent based system, it is possible to have a reaction between the two. It might soften the PVC a little and possibly warp it. If you are going to apply epoxy to it make sure to scuff sand it to create a profile for the epoxy to adhere to.
I would just tape it off and not coat it.
