Some reflections on wettability and adhesion

Studies done many years ago on joints formed between polyethylene and a conventional epoxy adhesive are reexamined. It is reemphasized that, for this system, there is no direct correlation between wettability (as measured by critical surface tension of wetting,γ C , or by contact angle, θ) and joint strength. In addition, other studies involving post-formation thermal treatment of joints containing certain polymer films provide further lessons about wettability and about the importance of performing studies of adhesion' over a range of temperature to avoid forming incorrect conclusions about adhesion based on studies done on such films at a single temperature.