This recommended practice describes the physical and chemical characterization techniques for identification of epoxy adhesive and prepreg resin systems in order to verify the chemical formulation, resin B-staging (See 8.1), cure reaction rates, adhesive moisture content, and resin component mix ratios, as necessary to achieve manufacturing and quality producibility and engineering performance.

Application:

While these techniques have been developed and validated for epoxy adhesive and prepreg resin systems, they are expected to be applicable to other thermoset materials, such as phenolics, polyimides, or polyesters. It is the responsibility of the user of the materials to establish limits on the acceptable variations of compositional parameters from the standard or baseline values of the original formulations qualified for use. When established, these variations should be included in applicable material specifications.

Limitations:

These techniques have been developed to detect chemical formulation variations in epoxy systems. Chemical formulation variations have not been quantitatively related to changes in mechanical properties, long-term durabilities, or moisture sensitivities of the material. These techniques should not be considered all-inclusive. The equipment used herein is generally applicable to the quantitative and qualitative analysis of epoxy resins; however, specific materials, other than those discussed herein, may require modified techniques.

Justification:

The procedures described herein are the result of extensive evaluations of structural epoxy adhesive and resin formulations applicable to aerospace applications.