Non-phosphorus Glucosyl Schiff bases for smoke inhibition and mechanical enhancement of epoxy resin composites

To improve the poor thermal stability of glucose, three glucose-based Schiff bases, named CG, SiG and UG, were synthesized as flame retardants for epoxy resin (EP) through the condensation reaction between glucose and three -NH2 containing substances, i.e. chitosan, 3-aminopropyltriethoxysilane and metal organic framework material (UIO-66-NH2), respectively. Subsequently, three flame retardant-modified EPs were obtained using a melt copolymerization method. EP/20 %SiG and EP/20 %UG obtained UL-94 V-1 rating with LOI values of 28.3 % and 27.4 %, respectively. The results of the cone calorimetry tests showed that these three modified EPs had superior inhibition of smoke production. The flame-retardant mechanism was systematically investigated, and furthermore, the study also highlighted the mechanical properties of the three modified samples and all showed significant improvement. This work suggests that glucose-based environmentally friendly flame retardants could facilely and effectively improve the fire safety of epoxy resin.