Disecondary Amine Synthesis and Its Reaction Kinetics With Epoxy Prepolymers

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Polymer Science and Engineering


3,3′-Diaminodiphenyl sulfone (3,3′-DDS) was reacted with acetaldehyde in the presence of sodium triacetoxy borohydride via reductive amination to yield a 3,3′-DDS based secondary diamine, N,N′-diethyl-3,3′-diaminodiphenyl sulfone. Near IR analysis indicated that the 5060 cm−1 peak for primary amine (—NH2) in 3,3′-DDS was absent in the reaction product spectrum. The —NH2 proton peak at δ 5.66 ppm shifted to δ 6.16 ppm in the product. Methyl and methylene protons of CH3—CH2—NH—Ph— group were observed at δ 3.01 and 1.12 ppm, respectively, in the product. The carbon NMR spectrum of the reaction product showed new peaks at δ 37.46 and 14.47 ppm that further confirmed secondary amine formation. The liquid chromatography coupled mass spectra peaks at 248–250 for 3,3′-DDS and 304 for the reaction product further supported the formation of N,N′-diethyl-3,3′-diaminodiphenyl sulfone. A blend of N,N′-diethyl-3,3′-diaminodiphenyl sulfone with diglycidyl ether of bisphenol-A (DGEBA) epoxy prepolymer started reacting at about 110–125°C surpassing an energy barrier of ∼ 66 kJ/mol as determined via differential scanning calorimetry analysis. Reaction kinetics were characterized via near IR spectroscopy specific to the reaction between secondary amine and DGEBA epoxy prepolymer. The results confirmed >97% conversion at a cure protocol of 5 h at 80°C, 5 h at 100°C, 11 h at 125°C, and 6 h at 185°C. N,N′-diethyl-3,3′-diaminodiphenyl sulfone-DGEBA thermoplastics displayed tensile and flexural modulii of 3.08 and 2.86 GPa, respectively, and glass transition temperature (Tg) of 120.77°C. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

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Journal of Applied Polymer Science





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