Composite Repair System with Long-Term Latency
Abstract
Novel latent epoxy hardeners which show promise for the field repair of composite structures of naval aircraft have been developed. At least one hardener is latent with epoxy resins for four to five months and exhibits good moisture resistance. These materials may provide the basis for a prepreg material to be used for the repair of graphite structural composites. Latent hardeners were prepared by reacting primary diamines with phthalic anhydride or phthalimide. These adducts are stable with multifunctional epoxy resins (MY 720 and 0510) at ambient temperatures and cure the resins at 150 deg C (302 deg F). DSC analyses show heats of reaction centered in the 101-120 deg C range, indicating that complete cures may be achieved at these lower temperatures. Initial studies show Tg's to be relatively high (120 to 146 deg C) and temperature/humidity resistance to be good. The mechanism of the latency of these materials was explained by analogy with HT 939, a CIBA-GEIGY latent hardener containing diethylenetriamine (DETA). HT 939 is incompatible with the standard epoxy resins, but becomes compatible on heating and reacts.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1981
- Accession Number
- ADA116472
Entities
People
- Jonas Weiss