Which glue do I need to glue hard inflexible plastic to flexible rubber??

[Thankyouandgoodnight]

ie my orthotics to my flip flops!!

Anyone??

araldite?

Glueing pastics is hard - had to do some stuff on upvc windows recently and found a tube of some silicon based type stuff which seems to be very good BUT problem you may have is that the joint will be constantly under pressure to flex. This is the stuff used - not sure it would be tough enough for what you want. Need to know what type of plastics are involved!