Couple of additions:
1) Super glues ("CA glue") and PTFE have such vastly different maximum operating temps, if the CA glue is OK, then you could use some more easily bondable insulator with a lower temperature rating than PTFE.
2) PTFE can be bonded with CA glues or other adhesives, if it is first surface treated with an appropriate etchant. A common one is simply sodium metal dissolved in a non-protic solvent (e.g, sodium dissolved in naphthalene plus an ether). Obviously, such surface prep solutions are very sensitive to water, but the PTFE, once treated, is not.
John