Accession Number : ADA302998

Title :   Physical Aging in Graphite Epoxy Composites.

Descriptive Note : Technical memo.,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER

Personal Author(s) : Kong, Eric S. ; Lee, Susanna M. ; Nelson, Howard G.

PDF Url : ADA302998

Report Date : APR 1981

Pagination or Media Count : 25

Abstract : Matrix-dominated mechanical behavior of a graphite/epoxy composite has been found to be affected by sub-Tg annealing. Postcured (+ or -45 deg)4s specimens of Thornel 300 graphite/Narmco 5208 epoxy were quenched from above Tg and given a sub-Tg annealing at 140 deg C for times up to l0(exp 5) min. The ultimate tensile strength, strain-to-break, and toughness of the composite material were found to decrease as functions of sub-Tg annealing time. No weight loss was observed during the sub-Tg annealing. The time-dependent change in mechanical behavior is explained on the basis of free-volume changes that are related to the physical aging of the nonequilibrium glassy network-epoxy. The results imply possible changes in composite properties with service time. jg p3

Descriptors :   *AGING(MATERIALS), *COMPOSITE MATERIALS, *GRAPHITE EPOXY COMPOSITES, MECHANICAL PROPERTIES, TENSILE STRENGTH, TIME DEPENDENCE, PHYSICAL PROPERTIES, TOUGHNESS, GLASS, NONEQUILIBRIUM FLOW, WEIGHT REDUCTION.

Subject Categories : Laminates and Composite Materials
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE