Accession Number : ADA135390

Title :   Development of a Stable Epoxy Resin System for Composite Repair.

Descriptive Note : Final rept. 22 Sep 81-15 Nov 82,


Personal Author(s) : Weiss,J

PDF Url : ADA135390

Report Date : Mar 1983

Pagination or Media Count : 24

Abstract : Novel latent epoxy hardeners which show promise for the field repair of composite structures of naval aircraft have been developed and tested. Two hardeners, phthalamides of 1,2-diaminocyclohexane (DACP) and of m-xylylenediamine, were latent with multifunctional epoxy resins for 4 to 12 months and yield glass transition temperatures of 145C and 130C respectively, when cured at 150C. Fracture toughness (KIC) of a DACP/MY 720 molding is 2.27 kg/mm 3/2. Slightly higher than that of a standard diaminodiphenyl sulfone (DDS)/MY 720 system. Graphite prepreg was made using DACP/MY 720 and DDS/MY 720 matrix resins, and unidirectional, well-consolidated laminates were prepared at low pressure (100 psi). Short-beam-shear and tensile values for the phthalamide laminate range between 72% and 105% of the values determined for the DDS/MY 720 laminate. Dynamic mechanical analysis shows the Tg of the DACP laminate to be 130C and to decrease by about 90C with 1.1% water absorption on aging at 49C and 95% relative humidity. This hot/wet conditioning reduces shear and tensile properties much more than for the DDS/MY 720 control laminate.

Descriptors :   *Composite structures, *Repair, *Epoxy resins, Naval aircraft, Hardening, Transition temperature, Curing, Fracture(Mechanics), Toughness, Laminates, Shear properties, Tensile properties, Mechanical properties, Dynamic pressure, Aging(Materials), Test methods

Subject Categories : Aircraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE