Abstract
We report a flame retardant epoxy nanocomposite reinforced with 9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide (DOPO)-tethered SiO2 (DOPO-t-SiO2) hybrid nanoparticles (NPs). The DOPO-t-SiO2 NPs were successfully synthesized through surface treatment of SiO2 NPs with (3-glycidyloxypropyl)trimethoxysilane (GPTMS), followed by a click reaction between GPTMS on SiO2 and DOPO. The epoxy nanocomposites with DOPO-t-SiO2 NPs as multifunctional additive exhibited not only high flexural strength and fracture toughness but also excellent flame retardant properties and thermal stability, compared to those of pristine epoxy and epoxy nanocomposites with a single additive of SiO2 or DOPO, respectively. Our approach allows a facile, yet effective strategy to synthesize a functional hybrid additive for developing flame retardant nanocomposites.
Highlights
Over the past decade, thermoset epoxy has been widely used in infrastructure and industry, including automotive, aircraft, aerospace and ocean, due to their advantageous mechanical properties, electrical insulation performances, thermal stability and chemical resistance [1,2,3]
The nanocomposites exhibited the excellent flame retardancy without a loss of mechanical properties, which is analyzed through cone calorimeter and limiting oxygen index (LOI) test
A given amount of DOPO-t-SiO2 and DGEBA as epoxy resin of 40 g was mixed for 10 min at 25 ◦ C, using a planetary centrifugal mixer (ARE 310, Thinky corporation, Tokyo, Japan) capable of shear mixing through rotation and revolution, in which the amount of the additives is expressed in parts per hundred of resin
Summary
Thermoset epoxy has been widely used in infrastructure and industry, including automotive, aircraft, aerospace and ocean, due to their advantageous mechanical properties, electrical insulation performances, thermal stability and chemical resistance [1,2,3]. To improve the stiffness of epoxy with intrinsically high cross-linking density, incorporating of inorganic NPs -SiO2 for the almost cases-has been considered, giving rise to increased impact resistance [25,26,27,28] For designing these types of composite materials, archiving homogeneous dispersion of the NPs within polymeric matrix is one of the most important factors because the NPs are likely to be aggregated by their high surface energy compared to that of polymer, which cause the inhomogeneity of mechanical properties of composites [29,30,31,32]. The functionalization of SiO2 NPs by commercially available 3-glycidyloxypropyl)trimethoxysilane (GPTMS) provided reactive site from epoxide ring, allowing for hybridization between SiO2 and DOPO via the click reaction to simultaneously improve mechanical properties and thermal stability of the epoxy nanocomposites with the DOPO-t-SiO2 NPs as single filler. The nanocomposites exhibited the excellent flame retardancy without a loss of mechanical properties, which is analyzed through cone calorimeter and limiting oxygen index (LOI) test
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