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>Synthesis, characterization, and polymerization of bismaleimides and bisnadimides chain‐extended byN,N′‐substituted ureas
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Synthesis, characterization, and polymerization of bismaleimides and bisnadimides chain‐extended byN,N′‐substituted ureas
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机译：Synthesis, characterization, and polymerization of bismaleimides and bisnadimides chain‐extended byN,N′‐substituted ureas
AbstractA series of new polymer precursors such as bismaleimides, bisnadimides, and bismethylnadimides chain‐extended byN,N′‐substituted ureas was synthesized and characterized. They were prepared by reacting a diamine containing ureylene linkages with maleic/nadic/methylnadic anhydride. Another alternative method for preparing these monomers included reaction of a diamine (1 mol) with an equimolar amount of maleic/nadic/methylnadic anhydride, subsequent reaction with a diisocyanate (0.5 mol) followed by cyclodehydration of the itermediate diamic acid. The monomers were characterized by infrared (IR) and proton nuclear magnetic resonance (1H‐NMR) spectroscopy. Their thermal polymerization was investigated by differential thermal analysis (DTA). The thermal stability of the polymers was evaluated by dynamic thermogravimetric analysis (TGA) and isothermal gravimetric analysis (IGA). No weight loss was observed when the polymers containing arylureas in their backbone were heated up to 324–334°C in nitrogen or air atmospheres. Their anaerobic char yield at 800°C fluctuated between
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