On oxygen plasma-treated polypropylene interfaces with air, water, and epoxy resins. II. Epoxy resins
Article first published online: 10 MAR 2003
Copyright © 1991 John Wiley & Sons, Inc.
Journal of Applied Polymer Science
Volume 42, Issue 7, pages 2045–2052, 5 April 1991
How to Cite
Occhiello, E., Morra, M., Morini, G., Garbassi, F. and Johnson, D. (1991), On oxygen plasma-treated polypropylene interfaces with air, water, and epoxy resins. II. Epoxy resins. J. Appl. Polym. Sci., 42: 2045–2052. doi: 10.1002/app.1991.070420732
- Issue published online: 10 MAR 2003
- Article first published online: 10 MAR 2003
- Manuscript Accepted: 25 JUL 1990
- Manuscript Received: 12 JUL 1990
XPS, SEM, SSIMS, FTIR-ATR, water-in-air, and air-in-water contact angle measurements have been used to unambiguously characterize the locus of failure of PP/epoxy joints. In the case of untreated PP, the fracture has been found adhesive, whereas in oxygen plasmatreated PP, it is cohesive, within bulk PP, but close to the modified PP-bulk PP interface. The smoothness of fracture surfaces allowed us to exclude mechanical interlocking effects. Shear-strength measurements showed that the mechanical strength of the joint was improved by plasma treatment. Preliminary thermal equilibration of the plasma-treated PP sample and changes in the curing cycle of the epoxy resin did not change either the locus of failure or the shear strength of the joint. The reason is probably because the number of polar functions left at the surface after thermal equilibration is sufficient to induce adhesion. The mechanical strength of the PP surface layer may be the determining factor. Fracture energy calculations showed that the observed locus of failure is the same as predicted on the basis of surface energy considerations.