This work reports an effective self-intumescent flame retardant system for epoxy resin (EP) based on the remarkable synergistic effect between Cu 2 O and ammonium polyphosphate (APP). The effect of Cu 2 O/APP on improving EP's fire performance was evaluated by limited oxygen index (LOI), UL-94, and cone calorimeter test. The optimal mass ratio of Cu 2 O: APP was shown to be 2:8. With 15 wt% total flame retardant loading, the EP with optimum Cu 2 O/ APP formulation reached V-0 classification and high LOI (33.5%), while the EP with APP only got NR and low LOI (26.5%). Additionally, the pHRR, total heat release, total smoke production, CO production of the EP with optimum Cu 2 O/APP formulation were primarily decreased. All the improvements were ascribed to the formation of the self-intumescent char layer of EP resulted from the catalyzing effect of Cu 2 O for char formation and CO to CO 2 conversion. These findings will consolidate approaches for conferring flame retardancy to flammable polymers or their blends.
Novel c-6 position oxidized corn
starch (OST) with high carboxyl
content (26.3–54.5%) was prepared by a green method, using
hydrogen peroxide as the oxidant. The as-obtained OSTs were then used
as flame-retardant carbon sources with microencapsulated ammonium
polyphosphate (MFAPP) in epoxy resin (EP). Compared to EP, the obtained
EP/MFAPP/OST composites exhibit significantly enhanced flame retardancy.
The introduction of only 6.25 wt % OSTs and 6.25 wt % MFAPP results
in remarkably increased limiting oxygen index and decreased heat release
rate, and all composites can reach UL94 V-0 rating. Thermogravimetric
analyses and cone calorimetry results suggest both OSTs and MFAPP
have good catalytic charring effects, and the increased carboxyl content
benefits the char formation of the composites. Because of the formation
of compact char on the sample surface during combustion, the transfer
of oxygen, heat, and flammable gas products is inhibited; the flame
retardancy of EP/MFAPP/OST composites is thus remarkably enhanced.
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