Disecondary amine synthesis and its reaction kinetics with epoxy prepolymers

• Published in: Journal of applied polymer science Vol. 126; no. 6; pp. 1929 - 1940
• Main Authors: Pramanik, Monoj, Mendon, Sharathkumar K., Rawlins, James W.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 15.12.2012; Wiley; Wiley Subscription Services, Inc
• Subjects: Amines; Applied sciences; Chemical properties; Deltas; DSC; epoxy; Exact sciences and technology; Infrared radiation; Materials science; near IR; Polymer industry, paints, wood; Polymers; Prepolymers; Properties and testing; Reaction kinetics; Reaction products; secondary amine; Sodium; Sulfones; synthesis; Technology of polymers; synthesis; Molecular structure; epoxy; Curing agent; Epoxy resin; Curing (plastics); Experimental study; Glass transition temperature; Thermal properties; Diamine; near IR; DSC; Kinetics; Chemical reactivity; Chemical synthesis; Secondary amine
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.36985

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