The peel ply surface treatment for adhesive bonding of composites: A review

This paper reviews existing literature related to the peel ply surface treatment of composite materials. A peel ply fabric is used as a removable layer in a composite lay-up and ripped off to modify the surface for adhesive bonding. A peel ply can affect the elemental composition of a surface and it is possible to distinguish between either a polyester or a polyamide peel ply treatment for a specific composite system and application. However, consistent and generalised relationships between the compositional modification or the surface energy and adhesive or resin adherence to treated surfaces are not probable. A compositional analysis and surface energy measurements are affected by the fractured matrix, peel ply fibre cavities and revealed reinforcements. Only a few recent studies have presented results for the regions of the matrix fracture and fibre cavities separately. Resin-impregnated peel plies, namely tear plies, offer additional tailorability for composite surface treatments, but related research is scarce.