BIODEGRADATION OF COMPOSITE-MATERIALS

Fiber-reinforced polymer composites were examined for susceptibility t o microbiologically-influenced degradation. Composites, resins, and fi bers were exposed to sulfur/iron-oxidizing, calcareous-depositing, amm onium-producing, hydrogen-producing, and sulfate-reducing bacteria (SR B) in batch culture. Surfaces were uniformly colonized by all physiolo gical types of bacteria; however, the microbes preferentially colonize d surface anomalies including scratches and fiber disruptions. Epoxy a nd vinyl ester neat resins, carbon fibers, and epoxy composites were n ot adversely affected by the microbial species. SRB degraded the organ ic surfactant on glass fibers. Hydrogen-producing bacteria appeared to disrupt bonding between fibers and vinyl ester resin and to penetrate the resin at the interface. Acoustic emission testing demonstrated re duction of tensile strength in a stressed carbon fiber-reinforced epox y composite after exposure to SRB.