Reaction kinetics and mechanical properties of Al2O3/epoxy-cyanate ester composites

The bisphenol A epoxy resin (E51) and bisphenol A cyanate (BCE) were used as the raw materials to study the co-curing reaction kinetics mechanism. At the same time, E51-BCE was used as the matrix resin, and Al2O3 obtained with Sol-Gel method as reinforcement to prepare the Al2O3/E51-BCE composites. The solidification process and curing kinetics of the system were determined by non-isothermal DSC, and the apparent activation energy of the system are 66.13 kJ/mol and 69.46 kJ/mol according to the Kissinger and Ozawa equation, respectively. Infrared spectroscopy was used to track the reaction route of the system at the initial curing temperature of 160℃ and 180℃. The results reveal that E51 reacts directly with BCE when the curing temperature starts at 160℃. The BCE's reactivity will be improved when the curing temperature is 180℃, BCE is mainly consumed in the self-polymerization reaction, and the formation rate of the triazine ring is accelerated. A little part of BCE directly reacts with E51 to form an oxazoline structure. The FTIR and TEM results of Al2O3 show that the structure of Al2O3 is a short fiber-like crystal with a little amount of hydroxyl groups on its surface. The SEM patterns of the Al2O3/E51-BCE composites indicate that Al2O3 presents as disperse phase in matrix, the interface between Al2O3 and matrix is fuzzy and the failure cracks are irregularity, thus it is typical ductile fracture. 3wt% Al2O3 is uniformly dispersed in matrix, and the impact strength and bending modulus of Al2O3/E51-BCE composites is 24.2 kJ/m2 and 2.54 GPa, respectively, which are increased by 53.65% and 22.12% compared with E51-BCE matrix resin. The mechanical properties of Al2O3/E51-BCE composites are improved obviously. © 2020, Editorial Office of Acta Materiae Compositae Sinica. All right reserved.