FRP Corrosion Resistance: The Role of the Glass Fibre Type

Abstract

The corrosion resistance studies of glass fibre reinforced plastics (RP) have primarily compared the resins and the surfacing veil materials using the ASTM C581 standard test method. As the corrosion barrier has been shown to delay and not stop the acid attack on the structural layers of the laminate, the more recent papers, by several authors, highlight the importance of the reinforcing fibres. In particular, the use of ECRGLAS® fibres is recommended in RP laminates subjected to the simultaneous stresses of mechanical loading and exposure to dilute material acids. A brief overview of the most pertinent literature related to the present work is given.

The experimental data on the resistance of RP laminates to corrosion attack in aqueous solutions of both sodium hydroxide and sulphuric acid is discussed. This work comprises a two level fraction factorial experiment design to study five factors: the glass fibre type (E vs. E-CR), the resin type (isophthalic vs. bisphenol A), the laminate construction (mat/mat/mat vs. mat/woven roving/mat), the exposure media type (sodium hydroxide vs. sulphuric acid) and the acid/base ion concentration (IN vs. 2N).

The laminates are compared using mechanical properties, and their retention, after exposure to the corrosive environments for up to 4 years.

Analysis of this study shows that E-CR glass offers improved performance compared to E glass in both environments. E-CR glass is significantly more resistant to sulphuric acid attack over long term exposure. In sodium hydroxide, E-CR glass performs better than E glass in the short term of up to 10 months. Neither glass type is able to resist sodium hydroxide attack in the long term. The resin type also plays a significant role in the corrosion resistance but mainly in the long run and primarily insodium hydroxide medium. The ion concentration and the laminate type are much less significant. The two glass types are also compared using C581 methodology. Again, E-CR outperforms E glass in the acidic environment and this effect increases with the increase in the exposure time.

ECRGLAS® is a registered trademark of Owens-Corning Fiberglas Corporation. Fiberglas Canada Inc. is a registered user.

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