Magnesium hydroxide micro-whiskers as super-reinforcer to improve fire retardancy and mechanical property of epoxy resin

Aiming to endow the efficient fire safety to epoxy resin (EP), magnesium hydroxide micro-whiskers (mw-MH) as super-reinforcement were incorporated into EP. The thermal kinetics of EP/mw-MH micro-composites were investigated. The limited oxygen index (LOI) of EP with the incorporation of mw-MH reached up to 33.7% greatly improved comparing to 26.3% of pristine EP. The cone calorimeter test (CCT) showed the heat release rate (HRR), smoke production rate (SPR) of the EP/3mw-MH with the addition of 3 wt% mw-MH obviously reduced, as evidenced by the reduction of peak of HRR and SPR for the micro-composites to 58% and 48%, respectively. Moreover, improvements were also observed in total heat release (THR) and total smoke production (TSP) of EP/3mw-MH, which were decreased by 29% and 34% at 300 s. Compared with common used industrial magnesium hydroxide (ind-MH), EP/mw-MH micro-composites possessed excellent fire safety performance at the same loading, which was attributed to the jammed network structure. Furthermore, the Young's modulus and tensile strength of EP/mw-MH micro-composites maintained. Finally, further investigation was proposed to explain the flame retardant mechanism, which involved the jammed network structures at internal and compact protective char. The magnesium hydroxide with one-dimensional structure offered an effective method to improve the fire retardancy of polymers.