Crosslinking reaction of epoxy resin (diglycidyl ether of bisphenol A) by anionically polymerized polycaprolactam: I. Mechanism and optimization

Different ratios of epoxy resin, diglycidyl ether of bisphenol A (DGEBA) and Ε-caprolactam (starting from 10:90 DGEBA and vice versa), were used to synthesize reactive DGEBA and polycaprolactam blends by the anionic polymerization of Ε-caprolactam at 140°C. Anionic polymerization was conducted with a strong base such as sodium hydride as a catalyst along with a cocatalyst such as N-acetyl caprolactam. The reaction mechanism, possible cure reactions, and reaction conditions of the reactive blends were studied with Fourier transform infrared spectroscopy and differential scanning calorimetry. The experiments were carried to study the optimization ratio and the effect of the composition on properties such as hardness and tensile strength of the reactive blends. The DGEBA was crosslinked by polycaprolactam through the reaction of the oxirane group with the amide nitrogen, and the reaction was very fast. A ratio of 80:20 (DGEBA: Ε-caprolactam) was optimum, and the resulting blend showed the highest tensile strength and hardness. © 2003 Wiley Periodicals, Inc.