Impact damage area and interlaminar toughness of modified FRP laminates

Glass fibre reinforced epoxy laminates are improved to enhance their impact tolerance capabilities by modifying the epoxy resin with the addition of CTBN 1300X8 and triphenylphosphine under a controlled atmosphere of inert nitrogen gas. When impacted by a steel projectile, the damage area of a modified laminate is significantly smaller (35-55%) than that of an unmodified laminate for the same impact energy level. The interlaminar energy release rate in Mode I (G Ic) is increased by 41% as a result of the modification while the interlaminar energy release rate in Mode II (G IIc) is enhanced by 47%. No significant adverse effects were found on the modulus or ultimate tensile strength. The modification of epoxy causes precipitation and separation of discrete rubber particles during curing of the epoxy which also enhances the interlaminar toughness and impact tolerance.