Flame retardancy, dielectric performance, pyrolysis behavior of epoxy resin and cyanate ester composites containing a multifunctional flame retardant

In this research, a novel multifunctional flame retardant (DSF) was prepared through a reaction involving 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), 4-amino-trifluorotoluene, and salicylaldehyde, was characterized by FTIR and H-1 NMR, and was employed to prepare a multifunctional epoxy resin and cyanate ester resin copolymer (EPCE). A comprehensive investigation was conducted to assess the mechanical performance, dielectric properties, thermal behavior, and flame retardancy of EPCE composites. The results indicate that the EPCE composite with 8 wt% DSF (EPCE/8DSF) attained a LOI value of 28.1 vol% and a V-0 rating. The EPCE/8DSF demonstrated a reduction of 25.8% in the peak heat release rate and a decrease of 25.6% in the total heat release in comparison with EPCE. In addition, the EPCE/8DSF composite demonstrated a decrease in both the dielectric constant and dielectric loss at 10 MHz, representing values of 3.58 and 0.00744, respectively. Furthermore, the incorporation of higher DSF content into the EPCE led to a decrease in mechanical properties.