Enhancements in LOX compatibility and fracture toughness of carbon fiber/epoxy composite for liquid oxygen cryotank by simultaneously introducing Al(OH)3 and phosphorous-nitrogen flame retardants

Abstract

Simultaneously enhancing the liquid oxygen (LOX) compatibility and fracture toughness at the cryogenic temperature of carbon fiber reinforced epoxy (CFRE) composites is critical for their successful application in LOX cryotanks. Herein, based on our previous work on optimizing the phosphorous-nitrogen containing organic flame retardant (TAD) content in epoxy resin for achieving the best LOX compatibility, the EP resins and CFRE composites modified with further incorporating inorganic flame retardant Al(OH)3 were fabricated. Specifically, the effects of introducing Al(OH)3 particles on the LOX compatibility and mechanical performances particularly at 90 K were thoroughly investigated. The results indicate that the Al(OH)3/TAD-EP resin (hence CFRE composite) with 4 phr Al(OH)3 exhibits an outstanding LOX compatibility without any impact reaction of burning, explosion, flash and charring observed in 20 samples. Moreover, the mode II fracture toughness of CFRE composites at room temperature and 90 K is improved by 27.3% and 16.7%, respectively with the addition of 4 phr Al(OH)3. Benefited with the simultaneous incorporation of 15 phr TAD and 4 phr Al(OH)3, the CFRE composite is promising for application in LOX tanks.