On Wed, 17 May 2017 17:39:56 +0800, Aussie wrote:

On 16-May-17 10:56 PM, wrote:
On Tue, 16 May 2017 15:47:13 +0800, 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?
I have used a two part plastic glue to bond some hard to bond
plastics. I'm not sure if the glue is an epoxy. I do know that it is
waterproof though. I bought the glue at the local hardware store and
it is made by Henkel (I think). I'm pretty sure the brand was Loctite
(and Loctite is now owned by Henkel). To repeat, I have used this glue
on some pretty hard to bond plastics and it worked very well. In fact,
it exceeded the performance guaranteed on the package.
Eric


Thanks. I'm kind of stuck with the bulk epoxy I have on hand.
I was thinking you could coat the PVC with the two part plastic glue
and then bond your epoxy to it.
Eric