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 C TBN 1300X8 and triphenylphosphine under a controlled atmosphere of inert ni trogen gas. When impacted by a steel projectile, the damage area of a modif ied laminate is significantly smaller (35-55%) than that of an unmodified l aminate for the same impact energy level. The interlaminar energy release r ate in Mode I (G(Ic)) is increased by 41% as a result of the modification w hile the interlaminar energy release rate in Mode II (G(IIc)) is enhanced b y 47%. No significant adverse effects were found on the modulus or ultimate tensile strength. The modification of epoxy causes precipitation and separ ation of discrete rubber particles during curing of the epoxy which also en hances the interlaminar toughness and impact tolerance.