Application of hexadentate Schiff base metal complexes as crosslinking agents for diglycidyl ether of bisphenol A

Nickel and zinc hexadentate Schiff base metal complexes have been synthesized and characterized by IR, NMR, FAB MS and elemental analysis. Crosslinking of the diglycidyl ether of bisphenol A (DGEBA) with these metal complexes gives Ni- and Zn-containing epoxy polymers. The crosslinking temperature could be lowered by using Bu4NOH as a basic catalyst. The properties of the metal-containing epoxy polymers investigated were glass transition temperature, thermal stability and tensile strength. Ni- and Zn-containing epoxy polymers obtained from the mole ratio of metal complex: DGEBA:Bu4NOH=1:10:0.2 showed Tg at 110 and 151°C, respectively and tensile strength of 45 and 41 N/mm2, respectively. Both metal-containing epoxy polymers have good thermal stability. Upon heating at 250°C for 48 h, the weight loss of Ni- and Zn-containing epoxy polymers were 2.3 and 3.7%, respectively, which is comparable to the DGEBA/maleic anhydride system.