Effect Of Different Iron Series Compounds On Combustion Properties In Intumescent Flame Retardant Epoxy Composites

Epoxy resins (EP) can be used as matrix of composite materials for several industrial applications due to its high performance, including superior chemical resistance and excellent superior mechanical properties, and so on. However, its poor fire resistance is one of the main disadvantages in using thermosetting resins for the composites. Therefore, improving the flame retardancy of EP is necessary.This article mainly studies smoke suppression properties and flame retardant effects of iron series compounds on intumescent flame retardant epoxy resins (IFREP). Then, the smoke suppression properties and synergistic flame retardant effects of iron series compounds on intumescent flame retardant epoxy composites were evaluated using cone calorimeter test (CCT), smoke density test (SDT), scanning electron microscopy (SEM), thermogravimetric analysis-infrared spectrometry (TG-IR).The flame retardant and smoke suppression effects between iron oxide compands and IFR are obvious. Compared with EP-0, the PHRR value of the sample with only 30 wt% IFR decreases from 940 kW/m2 to 282 kW/m2, the SF value of the sample decreases from 3668 mW/m2 to 708 mW/m2, the char residues mass of the sample increases from 0 to 32%. Compared with EP-1, the addition of 1 wt% ferrite yellow and 29 wt% IFR makes the PHRR value of EP material decrease from 282 kW/m2 to 175 kW/m2. The addition of 2 wt% iron oxide brown and 28 wt% IFR makes the SF value of EP material decreased from 708 mW/m2 to 69 mW/m2. The addition of 2 wt% iron oxide green and 28 wt% IFR makes the char residues mass of the sample increases from 32% to 58%. The TGA results show iron oxide compounds and IFR can decrease the initial decomposition temperatures of cured epoxy samples, and enhanced the residue amount at high temperature. The SEM shows that iron oxide compounds can promote charring and enhance the quality of char during combustion.It can be seen from CCT results that the smoke suppression and flame retardant effects of iron series compounds including Fe-OMT, ferrocene, and ferric phosphate are obvious. Compared with EP-1, the sample with only 30 wt% IFR, the addition of 1 wt% Fe-OMT and 29 wt% IFR makes the PHRR value of EP material decreases from 282 kW/m2 to 153 kW/m2. The addition of 2 wt% ferric phosphate and 28 wt% IFR makes the SF value of EP material decreased from 708 mW/m2 to 110 mW/m2. The addition of 2 wt% ferrocene and 28 wt% IFR makes the char residues mass of the sample increases from 32% to 47%. The TGA results showed iron series compounds and IFR can decrease the initial decomposition temperatures of cured epoxy samples, and enhanced the residue amount at high temperature. The SEM shows that iron series compounds can promote charring and enhance the quality of char during combustion. The iron series smoke suppression agents have a promoting effect on the formation of a dense carbon layer. The protective char layers formed on the surface of samples can not only prevent the further pyrolysis of materials, but also restrain the heat release and smoke generation.