Search

Graphene oxide (GO) is modified by melamine (MA) via the strong π- π interactions, hydrogen bonding, and electrostatic attraction. PP composites are prepared by melt compounding method, and GO/functionalized graphene oxide (FGO) is in situ thermally reduced during the processing. The results of scanning electron microscopy and transmission electron microscopy indicate that FGO nanosheets are homogeneously dispersed in polymer matrix with intercalation and exfoliation microstructure. The FGO/PP nanocomposite exhibits higher thermal stability and flame retardant property than those of the GO counterpart. During the thermal decomposition, the intercalated MA is condensed to graphitic carbon nitride (g-CN) in the confined micro-zone created by GO nanosheets. This in situ formed g-CN provides a protective layer to graphene and enhances its barrier effect. The heat release rate and the escape of volatile degradation products are reduced in the FGO-based nanocomposites. [ABSTRACT FROM AUTHOR]

In this work, a novel hyperbranched poly (urethane-phosphine oxide) (HPUPO) was facilely synthesized from 4,4′-diphenylmethane diisocyanate and trihydroxymethylphosphine oxide at room temperature. When HPUPO was incorporated, flame retardancy and toughness of epoxy resin are improved with maintained T g and increased modulus and strength. The gas and condensed phase flame retardant mechanisms and toughening mechanisms are provided. The poor compatibility of epoxy resin/HPUPO hybrids determines the unchanged T g of epoxy matrix phase. The tensile modulus and strength and storage modulus of modified epoxy thermosets are raised due to more rigid skeleton of HPUPO and hydrogen bond interaction. Moreover, the reactivity of epoxy resin curing systems containing HPUPO is elevated for the catalytic effect of its hydroxyl. The surface hydrophilicity of epoxy resin composites is decreased resulting from their increased surface roughness and the hydrophobicity of HPUPO. And the thermal decomposition temperature of epoxy resin hybrids is depressed. The epoxy resins modified by HPUPO with simple synthesis and preparation can be used for various high-performance applications in industries. [ABSTRACT FROM AUTHOR]