Difunctional effects of [Bmim][DBP] on curing process and flame retardancy of epoxy resin

To optimize the curing process and improve the flame retardancy of epoxy resin, 1-butyl-3-methylimidazolium dibutyl phosphate ([Bmim][DBP]) was used as a functional additive. In this study, [Bmim][DBP] was firstly blended into epoxy resin through a curing process. Then, the effect of [Bmim][DBP] on curing process was investigated using differential scanning calorimetry. The flame retardancy of modified epoxy resin was classified using the limit oxygen index and vertical burning test. The thermal decomposition behavior was investigated through a thermogravimetry. Finally, the Fourier transform infrared spectrometer and scanning electron microscopy were used to characterize the microstructures. Results revealed that [Bmim][DBP] has the potential for use as a flame-retardant hardener of epoxy resin. Moreover, the curing process of epoxy resin was found to be optimized when diethylenetriamine cooperated with [Bmim][DBP]. Similarly, the flame retardancy of epoxy resin was further improved when ammonium polyphosphate cooperated with [Bmim][DBP]. Furthermore, the thermal decomposition behavior of epoxy resin was relatively advanced by adding [Bmim][DBP]. In conclusion, [Bmim][DBP] could be used as a difunctional additive to optimize the curing process and flame retardancy simultaneously. Particularly, an optimal concentration of [Bmim][DBP] was proposed to be 1.5–2.0 mass%.