Early stages of degradation of polysulphide sealants in an aqueous environment

Polysulphide sealants are now widely used to ensure the integrity of fuel tanks on both civil and military aircraft. The consequences of failure of such sealants are severe both in terms of the length of time that the aircraft will be removed from service and the nature of the remedial work that must be carried out within the tanks themselves. It was against this background that a recent multi‐partner European Union Project MaSSPS (Materials System for Surface Protection and Sealing) was established. The members of the consortium include sealant manufacturers, aircraft manufacturers and other interested parties. The work to be presented in this paper concerns an extended study of the surface behaviour of candidate polysulphide sealant materials on exposure to water for times of up to 3 months. Coupons of research‐grade sealants were immersed in ultrapure water at 25°C and 55°C in a thermostated water bath. These coupons were examined by XPS, using a Thermo VG Scientific Sigma Probe spectrometer with monochromated Al Kα radiation, and by ToF‐SIMS, using a VG Scientific Type 23 instrument equipped with a two‐stage reflectron analyser. Copyright © 2002 John Wiley & Sons, Ltd.