Atomic oxygen degradation mechanisms of epoxy composites for space applications. (August 2019)

• Record Type: Journal Article
• Authors: He, Yanjun; Suliga, Agnieszka; Brinkmeyer, Alex; Schenk, Mark; Hamerton, Ian
• Is Part Of: Polymer degradation and stability. Volume 166(2019)
• Page Start: 108
• Page End: 120
• Publication Date: 2019-08
• Subjects: Epoxy resins -- Atomic oxygen -- Ultra-thin space composites -- Thermoset polymers -- Principal components analysis; AO Atomic oxygen -- LEO Low earth orbit -- VUV Vacuum ultra-violet -- ESA European space agency -- POSS Polyhedral oligomeric silsesquioxanes -- TGDDM Tetraglycidyl-4, 4′-diaminodiphenylmethane -- DGEBA Bisphenol a diglycidyl ether -- FTIR Fourier transform infrared -- ATR Attenuated total reflectance -- DSC Differential scanning calorimetry -- TGA Thermogravimetric analysis -- DMTA Dynamic mechanical thermal analysis -- PCA Principal components analysis -- ISS International Space Station -- JAXA Japan Exploration Aerospace Agency Japan -- LDEF Long duration exposure facility -- MISSE Materials international space station experiments -- NASA National Aeronautics and Space Administration -- SEM Scanning electron microscopy; Polymers -- Deterioration -- Periodicals; Stabilizing agents -- Periodicals; Polymères -- Dégradation -- Périodiques; Stabilisants -- Périodiques; 668.9
• DOI: 10.1016/j.polymdegradstab.2019.05.026
• Languages: English
• ISSNs: 0141-3910

Abstract

Abstract: The effects of atomic oxygen on three commercial composite materials, based on two space-qualified epoxy resins (tetraglycidyl-4, 4′-diaminodiphenylmethane (TGDDM) cured with a blend of 4, 4′-methylenebis(2, 6-diethylaniline) and 4, 4′-methylenebis(2-isopropyl-6-methylaniline); and a blend of TGDDM, bisphenol A diglycidyl ether (DGEBA), and epoxidised novolak resin initiated by N'-(3, 4-dichlorophenyl)-N, N-dimethylurea) are studied. Samples were exposed to a total fluence of (3.82 × 10 20 atom/cm 2 ), equating to a period of 43 days in low Earth orbit. The flexural rigidity and modulus of all laminates displayed a reduction of 5–10% after the first exposure (equivalent to 20 days in orbit). Fourier transform infrared (FTIR) spectra, obtained during prolonged exposure to atomic oxygen, were interpreted using multivariate analysis to explore the degradation mechanisms. Highlights: The degradation of two epoxy composites, in three laminates, following exposure to atomic oxygen, was studied. Samples were exposed to a total fluence of 3.82 × 10 20 atom/cm 2, equating to 43 days in low Earth orbit. The flexural rigidity and modulus of all laminates displayed a reduction of 5–10% after first exposure (equivalent to 20 days in orbit). Even at low AO exposure, a significant amount of surface resin had been removed to reveal the carbon fibres. The alkyl component degrades quickly during the reaction with AO, and the reaction between the AO and the CH forms hydroxy and carboxyl groups.