How a peel ply releases from the composite substrate to be bonded controls the surface quality and thus bond performance. Fracture between (blue arrow) the matrix resin of the impregnated “wet peel ply” and that of the composite substrate produces the best results.
SOURCE: “Evaluation of Peel-ply Materials on Composite Bond Quality”, Univ. of Washington and The Boeing Co.
There is a very informative post about peel ply and bonding on the Composites World Blog. A lot of good information about the subtleties of surface preparation.
