Journal Article Non-destructive evaluation by terahertz spectroscopy for penetration of acid solutions into epoxy resin

草野, 正大  ,  Kusano, Masahiro  ,  久保内, 昌敏  ,  KUBOUCHI, MASATOSHI  ,  BULGAREVICH, Dmitry  ,  志波, 光晴  ,  SHIWA, Mitsuharu

10 ( No. 11 )  , pp.941 - 949 , 2016-11 , Budapest University of Technology and Economics
Epoxy resins are used as high-performance thermosetting linings to protect substrates under corrosive environments.However, in a severe corrosive chemical solution, such protective layers may degrade with long time due to penetrationsof solvent and solute molecules into resin network. In this regard, the terahertz time-domain spectroscopy (THz-TDS)is a promising tool for non-destructive evaluation of the penetrant amounts due to high transparency of such plastic materialsand high sensitivity to the molecular vibrations in terahertz spectral range. In this work, the complex refractive indexes nand κ of epoxy specimens were measured after immersion into sulfuric acid solutions and compared with penetrated massfractions of water and acid ions. It was found that n and κ depended linearly with water and sulfuric acid mass fraction inspecimens, and κ of sulfuric acid immersed specimens was lager at higher frequency. While the calculated Δκ agreed wellwith THz-TDS measurement by THz-TDS, the calculated Δn was higher than the measurement. The difference may be attributedto the water and sulfuric states in the specimen.

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