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Unformatted text preview: ENVIRONMENTAL DEGRADATION OF CARBON NANOTUBE-MODIFIED COMPOSITE LAMINATES: A STUDY OF ELECTRICAL RESISTIVITY N. M. Barkoula,* A. Paipetis,* T. Matikas,* A. Vavouliotis,** P. Karapappas,** and V. Kostopoulos** Keywords : carbon fibre/epoxy laminates, carbon nanotubes, water absorption, electrical resistivity The environmental durability of carbon nanotube (CNT)-modified carbon-fibre-reinforced polymers (CFRPs) is in ves ti gated. The key prob lem of these new-gen er a tion com pos ites is the mod i fi ca tion of their poly mer ma - trix with nanoscaled fill ers. It was re cently dem on strated that the dam age tol er ance of these ma te ri als, as man - i fested by their frac ture tough ness, im pact prop er ties, and fa tigue life, can be im proved by add ing CNTs at weight frac tions as low as 0.5%. This im prove ment is mainly at trib uted to the in cor po ra tion of an ad di tional in ter fa cial area be tween the CNTs and the ma trix, which is ac tive at the nanoscale. How ever, this ad di tional in ter face could have a neg a tive ef fect on the en vi ron men tal du ra bil ity of the afore men tioned sys tems, since it is well known that the mois ture ab sorp tion abil ity of a ma trix is en hanced by the pres ence of mul ti ple in ter faces, which serve as an in gress route to wa ter. To ex am ine this prob lem, CNT-mod i fied CFRPs were ex posed to hy - dro ther mal load ings. At spec i fied in ter vals, the com pos ites were weighted, and the wa ter up take vs. time was re corded for both the mod i fied and a ref er ence sys tems. The elec tri cal con duc tiv ity of the com pos ites was reg - is tered at the same time in ter vals. Af ter the en vi ron men tal ex po sure, the interlaminar shear prop er ties of the con di tioned com pos ite sys tems were mea sured and com pared with those of un mod i fied com pos ites, as well as with the shear prop er ties of un ex posed lam i nates. 1. Introduction Car bon fi bre-re in forced poly mers (CFRPs) are widely used in many ap pli ca tions, such as aero space, civil, and de - fence in dus tries. This is mainly due to their low den sity and good me chan i cal prop er ties. How ever, one of the great est chal - lenges as so ci ated with the ap pli ca bil ity of these ma te ri als is their poor interlaminar tough ness, frac ture be hav iour, and fa tigue properties. The introduction of a nanoscaled reinforcement in otherwise conventional fibre-reinforced composites has opened an ex cit ing new area in the me chan ics of com pos ite ma te ri als. The unique prop er ties of these ma te ri als, com bined with the de - 21 0191-5665/09/4501-0021 © 2009 Springer Science+Business Media, Inc. *Department of Materials Science & Engineering, University of Ioannina, Greece. **Department of Mechanical En- gineering and Aeronautics, University of Patras, Greece. Corresponding author: A. Paipetis, Associate Professor, Department of Ma te ri als Sci ence & En gi neer ing, Uni ver sity of Ioannina, 45110 Ioannina, Greece. Rus sian trans la tion pub lished inof Ma te ri als Sci ence & En gi neer ing, Uni ver sity of Ioannina, 45110 Ioannina, Greece....
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- Spring '11