PLASMA DESORPTION TIME-OF-FLIGHT MASS-SPECTROMETRIC ELUCIDATION OF THE MECHANISMS OF ADHESION ENHANCEMENT BETWEEN PLASMA-TREATED PEEK-CARBON COMPOSITE AND AN EPOXYAMINE ADHESIVE

Plasma desorption time-of-flight mass spectrometry (PD-TOFMS) using ac celerated argon ions (9 MeV) has been successfully used for characteri zing the surface modifications induced at the surface of poly(ether et herketone) (PEEK) by cold plasma treatments. While the intact polymer structure leads to the emission of negative ions from fragmentation of the repeat unit, the degradation of such a structure under plasma exp osure gives rise to production of oxidized fragments. It is demonstrat ed that this production is highest for a plasma using a mixture of O-2 and N-2 (20:80), and that as a function of treatment duration, the ra te of oxidation of the modified surface layer correlates with adhesive strength, at least in a first step. PD-TOFMS is used for analysis of the failure patterns of epoxyamine adhesive/PEEK/carbon composite in o rder to localize the fracture position. It is concluded that the incre ase of the cohesion of the interphase layer as a function of the plasm a treatment duration leads to a shift from the interphase/PEEK interfa ce to the bulk of the matrial.