Most polysulphides are two-component systems and cure by interaction with a hardener that contains an oxidizing agent. Polysulfides are used as construction sealants, marine sealants and industrial sealants, and are also used in aerospace applications where resistance to jet fuel is necessary. They are used in the insulated glass market by window manufacturers for double-glazing applications, but have lost much of their market share to materials like polyisobutylene-based ("butyl") sealants in recent years. Applications in the construction industry are also under attack from alternative sealants such as high-performance silicones and polyurethanes. There have been concerns over supply and pricing in the last two years or so since one of the largest manufacturers of base polymers decided to exit the market completely. I would have no hesitation - from a technical point of view - in recommending polysulfides to you for demanding applications, but it might also be prudent to evaluate alternative technologies.
Q&A Exchange is written by Dr. Dave Dunn of F.L.D.Enterprises, a technical consultancy and full-service industrial market research firm specializing in the adhesives, sealants, specialty rubbers, and plastics fields. Dr. Dunn is a former vice president and director of Loctite Corp., and has spent many years troubleshooting adhesive and sealant problems. Questions for publication should be directed to him at 242 Trails End, Aurora OH 44202; (330) 562-2930; fax (865) 251-9687; e-mail DrDave242@att.net ; or visit http://www.fldenterprises.com .