Hyperbranched polyamine: A promising curing agent for a vegetable oil-based poly(ester-amide) resin

A hyperbranched polyamine (HBPA) has been synthesized by a nucleophilic displacement polymerization of cyanuric chloride with an aromatic diamine, 4,4′-(1,3-phenylene diisopropylidene) bis-aniline by using an A₂ + B₃ approach with high yield (>78%). The synthesized polyamine was characterized by ¹H NMR, ¹³C NMR and FT-IR spectroscopic studies, X-ray diffraction study, elemental and thermogravimetric analyses and by measurement of solubility and solution viscosity. The polymer is soluble in polar solvents like DMAc, DMSO, DMF, THF, etc. but insoluble in water and non-polar solvents. The flame retardancy as measured by limiting oxygen index (LOI) test of the polymer indicates its self-extinguishing characteristic. This hyperbranched polyamine has been utilized as an effective curing agent for a Mesua ferrea L. seed oil-based poly(ester-amide) resin. This hyperbranched polyamine alone as well as with conventional metal catalyzed peroxide system is found to effectively cure the above resin at dose levels of 2.5–10 phr. The hyperbranched polyamine not only enhances the rate of crosslinking reaction but it also improves many desirable performance characteristics especially the thermostability, flame retardancy, hardness, impact strength, chemical resistance, etc. of the cured resin. Thus this study indicated that this hyperbranched polyamine acts as a promising curing agent for poly(ester-amide) resin.