Kf. Lin et Wh. Wang, IMIDAZOLE AND CHROMIUM ACETYLACETONATE AS ADDITIVES FOR THE CURE AND FRACTURE-TOUGHNESS OF EPOXY-RESINS AND THEIR COMPOSITES, Polymer composites, 16(4), 1995, pp. 269-275
The effects of additives such as 2-undecyl-imidazole (C(11)Z) and chro
mium acetylacetonate (Cr(acac)(3)) were examined on the curing behavio
r and fracture toughness of tetraglycidyldiaminodiphenyl methane/diami
nodiphenyl sulphone (TGDDM/DDS) epoxy resins and their composites. The
C(11)Z additive alone reacted with TGDDM epoxy resins at about 127 de
grees C and increased the resin viscosity, resulting in an acceptable
resin content for composite processing. Further addition of Cr(acac)(3
) to TGDDM/DDS/C(11)Z formulation increased the fracture toughness 5.7
times compared to the typical TGDDM/DDS/BF(3)MEA epoxy formulation us
ed for the preparation of laminates. The interlaminar fracture toughne
ss of the laminates prepared by TGDDM/DDS/C(11)Z/Cr(acac)(3) formulati
on was only twice as much as that prepared by typical TGDDM/DDS/BF(3)M
EA. This was due to the fiber bridging contribution to the interlamina
r fracture toughness. Based on the experiment, this fiber bridging con
tribution was only dependent on the fiber content. Thus, the interlami
nar fracture toughness is approximated by the sum of the fracture toug
hness of epoxy matrix and the estimated fiber bridging contribution.