Relating Resin Mechanical Properties to Composite Delamination Fracture Toughness

The relationship between resin mechanical properties and the resultant composite Mode I and Mode II delamination fracture toughnesses in graphite-epoxy systems was examined. The tensile property that best correlated with composite delamina tion toughness was the resin tensile elongation. Resins with higher tensile elongations pro duced composites with a higher delamination toughness, though the relationship between the two may not be a simple one. The method used to toughen the resin affected the resulting composite delamination toughness. A rubber toughened resin would produce a tougher composite than would a resin that had the same tensile elongation (but with a lower crosslink density rather than rubber particle additions).