It looks like this gathered a bit of interest if even I was on the wrong track. I see now what you guys were talking about. The glass does come off easy, but it is the resin infused portion and what is left is mostly foam with no resin soaked into it. So it does in fact fail at the interface between the foam with resin and the foam without resin- the failure truly is in the core and not at the foam glass interface. Thanks for clarifying. Interesting stuff to think about and the more you get thinking the different roads it takes you down!
Now- time to go to school: I believe you guys are agin correct that the bond between eopxy and foam or glass is chemical and not only mechanical. Atleast this is true in the case of the fiberglass: this is after all why the silane or volan finish is put on- to be chemically compatible and give a strong bond. Now it must be realized that there are a few different kinds of chemical bonds, each having different bonding strengths. In the case of electrostatic bonds (refered to as 'specific adhesion’) as we have here- they are of the weaker bonds- similar to the hydrogen bonds in water. Don’t want to jump all the way in here, just wanted to mention.