Fire-Resistant Epoxy Anhydride and Epoxy Amine Compositions

The influence of stability conditions, processes of preventing stratification in epoxy polymers, optimal ratios between polymer matrices and flame retardants, and curing rheology on the possibility of providing the necessary level of fire safety and physicomechanical characteristics for epoxy polymers has been determined. The effect of flame-retardant fillers, such as aluminum and magnesium hydroxides and antimony(III) oxide, has been considered. It has been established that the simultaneous application of these flame retardants has a positive effect not only on the performability of filled epoxy compositions, but also on the efficiency in reducing the combustibility of an epoxy polymer due to an essential increase in the inflammation temperature. It has been shown that stability in inhibiting the precipitation of aluminum and magnesium hydroxides with a dispersity less than 10 μm in a lowly viscous epoxy anhydride composition is provided by adding 2–4 wt pts of antimony(III) oxide with a dispersity of 6–8 μm. This technological method, at an optimal aluminum and magnesium hydroxides/antimony(III) oxide ratio of 2.5 : 1, provides a rather high level of fire safety characteristics: an inflammation temperature up to 400–410°C with retention of a high level of physicomechanical properties. It has been revealed that the addition of the aforementioned flame retardants (Al(OH)3, Mg(OH)2, and Sb2O3) at quantities less than 5 wt pts has no significant effect on a decrease in the level of important physicomechanical characteristics, such as Charpy fracture toughness and ultimate tensile stress. This provides a broader application of epoxy adhesives at higher temperatures to be especially relevant in high-energy industry branches, where the use of epoxy polymers was limited earlier due to their increased combustibility. The ability of antimony(III) oxide to reduce the stratification of hydroxides in a polymer matrix due to the probable implementation of rather strong intermolecular interaction and the formation of a network of physical bonds in epoxy compositions has been confirmed.