jaros wrote:The bond between allready cured epoxy and a fresh epoxy is mechanical also, i believe. But not all mechanical bonds have the same strenght, that is true.the bond between plastic and epoxy is mechanical. The bond epoxy/epoxy is chemical. In theory, we would not need a core at all, like plane wings with ribs, etc.
It is Jaroš, however, the general rule is if epoxy on epoxy 24hrs after the first part, it is chemical. With normal curing. With heating post curing, everything accelerates.
I don't know anyone in the Aerospace industry but they might confirm how they cure carbon parts. This days heaps of planes are carbon.