Phosphorus- and silicon-containing amino curing agent for epoxy resin

Current research work focuses on the synthesis of phosphorus- and silicon-containing amine curing agent (PSA) for epoxy resins. PSA was synthesized using phenyl phosphonic dichloride and ethylenediamine as raw materials and further modification with 3-glycidoxypropyltrimethoxysilane. NMR, FTIR and amine value analysis were performed for the structure confirmation of the obtained product and intermediate. PSA was taken in different molar ratios for the crosslinking with epoxy resin before which the sol-gel technique was performed onto the product for self-crosslinking of the methoxy groups. The obtained formulations were applied onto the mild steel panels and cured in an oven. The thermal and mechanical properties of cured epoxy resins were analyzed by TGA, DSC, impact resistance, pencil hardness and flexibility. The thermal and mechanical properties were increased along with the heat resistance index temperature (T-HRI) toward the loading of PSA into the coating formulations. The flame retardant properties were also checked and found to be increased with respect to the increasing concentration of PSA because of the synergistic effect of P and Si atoms. The formulation with the highest amount of PSA showed the highest LOI as 29 with self-extinguishing behavior in the UL-94 test.