Our previous report proposed a gradual adhesion model for the interface of epoxy resin used as an electric insulator. The model can deal with the flow and gelling of epoxy resin but it cannot deal with the fracture of the interface. In order to solve the fracture problem, two new fracture models are proposed for the epoxy resin interface.
1) One model proposes that partial adhesion remains after the fracture of the interface of epoxy resin occurs. The calculated strain change using this model does not give good agreement with experimental values.
2) Another model proposes that partial adhesion remains after the shrinkage strain from the curing reaction is released by the fracture of the interface. The calculated strain change from this model gives good agreement with experimental values.
These results indicate that the weak adhesion region breaks away when the fracture of the epoxy resin interface occurs. The temperature distribution of the epoxy resin during the curing reaction does not change with the fracture of the interface. The internal stress of the epoxy resin goes up with the adhesion and goes down with the fracture of the epoxy resin interface.