Accession Number : ADA304532

Title :   Development of Tough, Moisture Resistant Laminating Resins.

Descriptive Note : Final rept.,

Corporate Author : GENERAL DYNAMICS SAN DIEGO CA CONVAIR DIV

Personal Author(s) : Brand, R. A. ; Harrison, E. S.

PDF Url : ADA304532

Report Date : SEP 1982

Pagination or Media Count : 49

Abstract : A study was conducted to develop tough, moisture resistant laminating resins for employment with graphite fibers. The new laminating resins exhibited cost, handleability and processing characteristics equivalent to 394K (250F) curing epoxies. The laminating resins were based on bisphenol A dicyanate (BPADC) and monofunctional cyanates with hydrophobic substituents. These resins have been shown to sorb only small quantities of moisture at equilibrium (0.5% or less) with minimal glass transition temperature (Tg) depression and represent an improvement over epoxies which sorb around 2% moisture at equilibrium. Toughening was accomplished by the precipitation of small diameter particles of butadiene-nitrile rubber throughout the resin matrix. The rubber domains act as microcrack termini and energy dissipation sites, allowing increased stress accommodation prior to catastrophic failure. A unique blend of amine terminated butadiene-nitrile elastomer (MW 2,000) and a high nitrile content butadiene-nitrile rubber yielded the desired resin morphology. Mechanical properties of unidirectional T-300 graphite and this resin showed lower as-fabricated interlaminar shear than a typical 250F cure epoxy due to the impact modifiers incorporated into the resin. Moisture sorption was also quite low (0.3% at equilibrium) and was probably due to the increased hydrocarbon nature of the blended resin. Neat resin samples show an apparent flexural modulus similar to 2,2-bis (p-cyanatophenyl) propane (BPADC) but with an eight-fold increase in ultimate flexural strength. The higher flexural strength is probably due to a higher strain accommodation provided by the precipitated rubber particles.

Descriptors :   *EPOXY LAMINATES, *CYANATES, *EPOXY RESINS, STRESS STRAIN RELATIONS, AGING(MATERIALS), CRACKING(FRACTURING), SYNTHESIS(CHEMISTRY), ELASTOMERS, ACRYLONITRILE POLYMERS, CARBON FIBERS, TOUGHNESS, MATRIX MATERIALS, IMPACT STRENGTH, TRANSITION TEMPERATURE, FLEXURAL STRENGTH, CURING, MOISTURE, HARDENING, CHEMICAL EQUILIBRIUM, HUMIDITY, BUTADIENES, PROPANE, GRAPHITE EPOXY COMPOSITES, NITRILE RUBBER, MOISTUREPROOFING, LAMINATED PLASTICS, BULK MODULUS.

Subject Categories : Organic Chemistry
      Laminates and Composite Materials
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE