항공기 복합재 수리용 프리프레그(Prepreg) 저장시한에 따른 수지 유동성 변화에 관한 연구

A Study on the Change in Resin Fluidity according to the Prepreg Storage Time Limit for Repairing Aircraft Composites

In this paper, we evaluated shelf life extension of prepreg used for repairing damaged composites applied to aircraft. Approximately 40% of resin in prepreg is impregnated in reinforcement fabric, and all resins are cured by a chemical reaction. Shelf life is the time that a product is stored in a good condition in an unopened container. Shelf life differs for each product. If a particular shelf life is exceeded, specific chemical reaction does not occur due to change of physical properties of constituents. And the cured part does not have sufficient strength. In this case, the material must be discarded. Secondly, after a test prescribed by manufacturing companies or the standard, if a measured value satisfies a required value, the material can be used by extending shelf life for a certain period of time. Tensile test, shear test, compression test, and resin fluidity test can be used as test methods to extend the shelf life required for the storage time limit. Among them, for the resin fluidity change test, which is the most frequent in the storage time extension test of the prepreg material, the storage time effective material and the storage time expiration material were evaluated to analyze whether the required value for the test method was satisfied. Therefore, it is expected to reduce the material cost by extending the prepreg expiration date by studying a method for extending the prepreg storage time limit.