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| In this work, Graphene oxide (GO) was modified by 4, 4 - diamino diphenyl methane (DDM) and then in situ incorporated into phosphoramide oligomer, resulting in the nanocomposite flame retardant (FRs-FGO) containing exfoliated graphene. Subsequently, the ?ame retardant (FRs-FGO) was incorporated into polypropylene (PP) and simultaneously compatilized with PP-grafted maleic anhydride. TEM results showed that the FGO was dispersed more uniformly in PP than the bare graphene oxide (GO), which was due to of strong interfacial interaction and the previous exfoliation of FGO in FRs before blending. The addition of FRs-FGO into PP led to a signi?cant improvement of the thermal stability at elevated temperature with higher char yields. Moreover, the crystallization and ?re safety properties of PP composites were also improved by the incorporation of FRs-FGO, including 11.4 C increase in crystallization temperature, 66.9% reduction in peak heat release rate, 24.4% decrease total heat release, and 73.0% decrease in ?re growth rate index. By contrast, simple blending of GO with FRs exhibited less improvement in fire safety properties than FRs-FGO, as suggested by cone results, resulting from the improved dispersion and thermal stability of FGO sheets. The flame retardant mechanism was due to the shielding effect of FGO and char layers, which could reduce the release of combustible gases and inhibit the mass and heat transfer between gas and condensed phases. |
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| Keywords:Polypropylene; Functionalized graphene oxide ; Nanocomposites flame retardant; Fire safety |
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