Effects of Combining Graphene Nanoplatelet and Phosphorous Flame Retardant as Additives on Mechanical Properties and Flame Retardancy of Epoxy Nanocomposite

Abstract

The effects of combining 0.1–5 wt % graphene nanoplatelet (GNP) and 3–30 wt % phosphorous flame retardant, 9,10- dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as fillers in epoxy polymer on the mechanical, flame retardancy, and electrical properties of the epoxy nanocomposites was investigated. GNP was homogeneously dispersed into the epoxy matrix using a solvent-free three-roll milling process, while DOPO was incorporated into the epoxy resin by mechanical stirring at elevated temperature. The incorporation of DOPO reduced the crosslinking density of the epoxy resin. When using polyetheramine as a hardener, the structural rigidity effect of DOPO overshadowed the crosslinking effect and governed the flexural moduli of epoxy/DOPO resins. The flexural moduli of the nanocomposites were improved by adding GNP up to 5 wt % and DOPO up to 30 wt %, whereas the flexural strengths deteriorated when the GNP and DOPO loading were higher than 1 wt % and 10 wt %, respectively. Limited by the adverse effects on mechanical property, the loading combinations of GNP and DOPO within the range of 0–1 wt % and 0–10 wt %, respectively, in epoxy resin were further studied. Flame retardancy index (FRI), which depended on three parameters obtained from cone calorimetry, was considered to evaluate the flame retardancy of the epoxy composites. DOPO showed better performance than GNP as the flame retardant additive, while combining DOPO and GNP could further improve FRI to some extent. With the combination of 0.5 wt % GNP and 10 wt % DOPO, improvement in both mechanical properties and flame retardant efficiency of the nanocomposite was observed. Such a combination did not affect the electrical conductivity of the nanocomposites since the percolation threshold was at 1.6 wt % GNP. Our results enhance the understanding of the structure–property relationship of additive-filled epoxy resin composites and serve as a property constraining guidance for the composite manufacturing.

Effect of the Matrix Melt Flow Index and Fillers on Mechanical Properties of Polypropylene-Based Composites

“…The addition of a small amount of GNP to PP was reported to improve the mechanical properties of the composite significantly [ 8 ]. GNP and TiO 2 nanoparticles were also reported can be functionalized as anti-ultraviolet [ 16 , 17 , 18 ] and flame retardant [ 19 , 20 , 21 ].…”

Flame Retardancy and Mechanical Properties of Chitosan and DOPO with Different Mass Ratios in Epoxy Resin

“…Applications in some elds were limited due to its signi cant ammable defects (Wang et al 2006). At present, the re resistancy of epoxy resins has been extensively studied and the addition of ame retardants is considered to be the most direct, e cient and economical usage mode (Tang et al 2019;Netkueakul et al 2020). However, the addition of ame retardants will generally reduce the mechanical properties of epoxy resin (Zou et al 2020).…”

A Study on a Magnesium-Based Layered Composite Used as a Flame Retardant for Phenolic Epoxy Resins

“…Current flame retardancy studies involve intercalation cations of LDHs, interlayer inorganic anions of LDHs, interlayer organic anions and surface modification [7]. Based on the two aspects of green synthesis MgAl-LDHs addition and anion intercalation, three characterization methods including thermogravimetric analysis, limiting oxygen index (LOI) and cone calorimetry are adopted to evaluate the effect of MgAl-LDHs on the flame retardance of EP [8]. Thermogravimetric analysis is mainly employed to study the functional relationship between the weight and energy of polymer materials and temperature, which can accurately measure the mass change and change rate of materials.…”