Thermal and Morphological Properties of Bisphenol Dicyanate–Epoxy–Bismaleimide Intercrosslinked Matrix Materials

Abstract

Intercrosslinked network of cyanate ester–bismaleimide modified epoxy matrix systems was developed. Epoxy systems modified with 4%, 8%, and 12% (by wt.) of cyanate ester were made by using epoxy resin and cyanate ester with diaminodiphenylmethane as curing agent. The reaction between cyanate ester and epoxy resin during the cure process of cyanate ester modified epoxy systems was studied using FTIR. The cyanate ester toughened epoxy systems were further modified with 4%, 8%, and 12% (by wt.) of bismaleimide (N,N′‐bismaleimido‐4,4′‐diphenylmethane). BMI–CE–epoxy matrices were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and heat deflection temperature (HDT) analysis. The studies indicate that the thermal stability and resistant to water absorption behavior of epoxy resin has been enhanced by the introduction of cyanate ester. However, glass transition temperature and heat deflection temperature are found to decrease with increasing cyanate ester concentration, whereas, the incorporation of bismaleimide into epoxy resin enhanced the thermal properties according to its percentage content. However, the introduction of both cyanate ester and bismaleimide influences the thermal properties according to their percentage content. Differential scanning calorimetry thermogram of cyanate ester modified epoxy and BMI modified epoxy during cure show an unimodel reaction exotherms. The fractured surface of cyanate ester modified epoxy systems reveals the presence of homogeneous morphology, and a smooth fractured surface is observed with increasing bismaleimide content.

Keywords:

• Epoxy resin
• Cyanate ester
• Matrix materials
• Glass transition temperature
• Thermal stability
• Morphology

Acknowledgment

The authors thank the Council of Scientific and Industrial Research Government of India, New Delhi 110 016, for financial support. The authors also thank Dr. V. Mohan, Chairmen, Faculty of Technology, Anna University, Chennai 600 025 for his help.