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how could i bound polyurethane and silicone ? Answered

I'm trying to make a two part model in polyurethane resin with a thin silicone membrane connecting them so it can expend  and still be maintained by the silicone layer.
The problem is that i need to pour the silicone into the model, so i can't make them stick together with some coating or glue.
Instead of the silicone i thought about using polyurethane elastomer but it is usually not very elastic and does not age well when frequently teared neither.
So i'm searching for a way to pour silicone into polyurethan resin and make it stick. Maybe eventually by putting some fiber on the resin surface while wet so it'll get trapped in the silicone layer while it will catalyze but i doubt it'll resist to the tear strengh for a long term use.
Did any of you tried it or found a solution to that problem ?


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4 years ago

not sure what shape casting you are going for but my first thought was:

cast the poly resin with some sort of easily removeable material (im thinking wax) to create a key space that will lock the silicone in place

cast the poly resin bottom of part 1 and 2 with the wax key in place.

remove the wax once the poly resin is set.

place the silicone in to the space left by the wax.

cast the poly resin top of part 1 and 2.

once the poly is cured the silicone is locked in place connecting parts 1 and 2.


Answer 4 years ago

Thanks for the quick answer.

Tthat could work indeed, but the problem is that i want my final to piece to be a closed sphere, with the poly as the outside layer and the silicone inside, only visible when the two half spheres are discarded.