Aussie wrote:
I'm playing around potting some electronics for immersion in water up
to 10 metres.

A cable with a polyethylene sheath and PVC insulated wires connected
to a circuit board are embedded in some rigid setting epoxy.

I know I'm not going to get the epoxy to adhere to the polyethylene.

What can I do to enhance the bond between the epoxy and the PVC wire
insulation to keep the water from wicking along the wire to the
circuit board?

I've read that brushing with PVC pipe glue primer (MEK) can help, as
well as flame treating.

Flame treating is impractical as the job is too small & tight to get
into the area where the PVC insulation is.

Any suggestions?

Is the MEK priming likely to help?

Perhaps painting on some sort of low viscosity RTV silicone that
might form an intermediary seal?


Use a heated plate to melt a rolled lip on the end of the poly tubing.
The lip will give the epoxy a mechanical bond. To ensure it doesn't leak
you could put a common O ring that fits the tubing above the lip. The
epoxy then encapsulates the ring and the lip.

--
Steve W.