CHARACTERIZATION OF PHENOLIC RESINS FOR COMPOSITE HONEYCOMB APPLICATIONS

In this study, phenol-formaldehyde resins catalyzed with sodium hydroxide, triethylamine and ammonium hydroxide were characterized and compared to a commercial honeycomb dip. All four resins displayed similar degradative mechanisms, and their degradation behavior was understood through GS/MS analysis. Flammability studies were also performed on glass fiber laminates manufactured from these resins. The sodium hydroxide and ammonium hydroxide catalyzed resins were found relatively inflammable, while the triethylamine catalyzed laminates burned readily. The flammability of the commerical system was linked to ethanol volatization. The various chemical properties responsible for these behaviors are discussed and analyzed in terms of the catalyst basicity, solubility and boiling point. Lastly honeycomb ring specimens were fabricated and resin fracture toughness was found to be more significant than the flexural strength in honeycomb ring compression tests.