ACCELERATED TESTING OF A FILLED POLYESTER E-GLASS COMPOSITE IN ACIDIC ENVIRONMENTS

This paper describes the results of an accelerated laboratory investigation to measure the rate of deterioration of a newly developed filled plastic composite exposed to acidic (sewage) environments. The specific objective was to compare the relative rates of deterioration of an experimental filled filament wound (FFW) polyester composite immersed in sulfuric (pH 2.23) and acetic (pH 2.22) acid environments at 45-degrees-C. Deterioration was measured in terms of changes in wet specimen weight, loss in dried (soluble) material weight and mechanical properties, the extent of chemical dissolution, and the depth of penetration. Based on regression analyses of these parameters, it was found that the rate of deterioration was a function of the square root of immersion time. Deterioration of the FFW composite in acetic acid was 1.6-3.9 times greater than in the sulfuric acid environment. The loss in wet flexural properties and the dissolution behavior of aluminum trihydrate were not influenced by the type of acid environment. Based on the findings of this study, sulfuric acid is recommended as a standard laboratory test medium for fiberglass reinforced plastic composites used in construction of sewage facilities and pipelines where deterioration due to sulfur oxidizing bacteria is anticipated.