MECHANICAL AND PHYSICAL-PROPERTIES OF ISOTHERMALLY AGED CARBON FIBER-EPOXY COMPOSITES

Isothermal aging of continuous carbon fiber-epoxy resin composites con taining epoxy resin derived from diglycidyl ether of bisphenol-A (DGEB A) and methylene dianiline (MDA) and 64 vol% of carbon fibers with ori entation angles of 0 degrees, 45 degrees, 90 degrees and crossply fibe rs was performed in vacuum, air and nitrogen atmosphere. The impact st rength of the 45 degrees ply composites increased from 149 kJ/m(2) to 15.5 x 10(2) kJ/m(2) after isothermal aging In vacuum at 200 degrees C for 13 h. The interlaminar shear strength (ILSS) of the 90 degrees pl y composites increased from 3 to 4 MPa after isothermal aging at 184 d egrees C for 336 h in nitrogen atmosphere. The flexural strength of th e 90 degrees ply composites, however, remained unchanged (similar to 8 0 MPa) after isothermal aging in nitrogen at 184 degrees C for 336 h, The impact strength of the 90 degree ply composites decreased by 20% ( similar to 15 kJ/m(2) to 12 kJ/m(2)) and 80% (similar to 15 kJ/m(2) to 3 kJ/m(2)) after isothermal aging in nitrogen atmosphere at 184 degre es C for 336 h and in air at 200 degrees C for 336 h, respectively.