The Effect of Barrier Coatings on the Cure Rate and Fluid Resistance of Polysulphide Sealants.
ROYAL AIRCRAFT ESTABLISHMENT FARNBOROUGH (ENGLAND)
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Two commercial barrier coating materials based on polyurethane and nitrile acrylonitrile-butadiene copolymer were used in conjunction with two of the most commonly used integral fuel tank polysulphide sealants catalysed with either dichromate or lead dioxide. The rate and degree of cure were only slightly reduced when either barrier coating was applied. Neither coating appeared to offer any improvement in fuel resistance but significant improvements were noted in the resistance of barrier coated sealants to the ingress of water. After 44 days at 40 C water uptake of dichromate cured sealant was reduced form 126 to 6 by barrier coating with polyurethane. A similar effect was noted with the lead dioxide cured sealant although not to the same degree since this material is inherently more resistant to water than the dichromate cured sealant. There is some doubt about the long term performance of the polyurethane barrier coating as samples appeared to embrittle on ageing. Author
- Adhesives, Seals and Binders
- Coatings, Colorants and Finishes