Thermal Characterization of Diglycidyl Ether of Bisphenol- A/Phosphorus Containing Amines PREETI JAIN, VEENA CHOUDHARY, I. K. VARMA Centre for Polymer Science and Engineering, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi-110016, India Received 5 May 2000; accepted 5 September 2000 Published online 27 April 2001 ABSTRACT: In order to improve the thermal resistance of diglycidyl ether of bisphenol- A (DGEBA), phosphorus-containing di- and tri-amines, i.e., bis (3-aminophenyl) methyl phosphine oxide (B) and tris (3-aminophenyl) phosphine oxide (T), were used as curing agents. The effect of phosphorus content on the curing characteristics and char residue of cured resins in nitrogen atmosphere was evaluated by using different molar ratios of conventional curing agent, i.e. 4, 4'-diaminodiphenyl sulfone (D) and amine B or T. Activation energy of curing, as evaluated by using the multiple heating rate method, was lowest when triamine T (61.0 kJmol -1 ) was used as hardener and was highest when D (68.7 kJmol -1 ) was used. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 390 –395, 2001 Key words: phosphorus-containing amines; curing; thermal stability; epoxy resins; heat of curing INTRODUCTION In order to extend the applications of epoxy resins as electronic material and in the aerospace indus- try, it is crucial to improve their flame and ther- mal resistance. Several approaches have been re- ported in the literature for improving the thermal and flame resistance of these resins. Aromatic bromine compounds, in conjunction with anti- mony oxide, have been widely used as flame re- tardants for epoxy resins in the past. The major problem encountered with these systems is the production of highly toxic and corrosive products during combustion. 1 Fire hazards and the envi- ronmental concerns of using halogen-based sys- tems, which have been publicized by political movements, have necessitated the search for new halogen free fire retardant agents. Organophosphorus compounds have demon- strated good ability as flame retardants. 2 These compounds form a carbonaceous char, thereby protecting the polymer surface from the flame action. 3 Beneficial interaction between flame re- tardants, i.e., the influence of phosphorus and nitrogen compounds, has long been recognized. Their combination leads to effects that are greater than would be expected from a linear combination of these elements alone. Flame re- tardants such as phosphorus-halogen mixtures, ammonium phosphate, and organophosphorus compounds have been used as additives to impart flame retardance to the epoxy resins. 4–6 Another approach for improving the thermal and flame resistance is the structural modifica- tion of epoxy resins or curing agents. Incorpora- tion of covalently bonded flame retardant groups in polymer backbone has attracted much atten- tion because a high efficiency in flame retardation is achieved by this method. 7–10 Our earlier studies with addition polyimides have shown that incorporation of phosphorus/ni- Correspondence to: I. K. Varma. Contract grant sponsor: Council for Scientific and Indus- trial Research (CSIR), Govt. of India (P.J.). Journal of Applied Polymer Science, Vol. 81, 390 –395 (2001) © 2001 John Wiley & Sons, Inc. 390