Effects of surface modification with amino branched polydimethylsiloxane (ABP) on the corrosion protection of epoxy coating

Abstract

An epoxy coating was designed to give a hydrophobic property on its surface by modifying it with three types of amino branched polydimethylsiloxane (ABP), and then effects of the modification on the structure, surface hydrophobic tendency, water transport behavior and hence corrosion protectiveness of the modified epoxy coating were examined using FT-IR spectroscopy, hygrothermal cyclic test, and impedance test. The surface of epoxy coating was changed from hydrophilic to hydrophobic property due primarily to a phase separation tendency between epoxy and modifier by the modification. The phase separation tendency is more appreciable when modified by ABP with higher molecular weight ABP at higher content. Water transport behavior of the modified epoxy coating decreased more in that with higher hydrophobic surface property. The resistance to localized corrosion of the modified epoxy coated carbon steel was well agreed with its water transport behavior and hydrophobic tendency. (c) 2007 Elsevier Ltd. All rights reserved.