Abstract
Manufacturing processes that involve the preparation or formation of alkaline bleach solutions experience an aggressive corrosive environment that can attack equipment constructed of both non-exotic metals and fiberglass reinforced plastic composites. Properly fabricated fiberglass reinforced plastic composites have satisfactorily resisted the corrosive attack of stable alkaline bleach. However, the ability of any fiberglass reinforced plastic composite to successfully withstand the corrosive effect of unstable bleach has been questionable.
It has been reported that alkaline bleach becomes unstable and forms a more corrosive environment when the pH of bleach decreases. In order to determine the aggressiveness of this environment, a study was undertaken to observe the corrosive effect of several alkaline pH adjusted bleach solutions on various types of vinyl ester resin composite laminates at both 150° and 210°F.
Results indicate that bleach solutions in the lower pH ranges are generally less corrosive towards the different resin composite systems observed than bleach solutions maintained at the higher pH ranges. The increase in temperature from 150° to 210°F also produced an increase in the corrosion rate by at least a factor of 2 in most cases.
A fire retardant bis A epoxy vinyl ester resin and two bis A epoxy vinyl ester resins were used in preparing the different fiberglass reinforced plastic composite laminates. The fire retardant bis A epoxy vinyl ester resin gave improved corrosion resistance over the two bis A epoxy vinyl ester resins.
The catalyst systems and veil materials used, as well as resin cure, had a definite influence on the resins’ composite systems’ ability to resist corrosive attack.
