Preparation of Cobalt Ferrite Nanoparticle-Decorated Boron Nitride Nanosheet Flame Retardant and Its Flame Retardancy in Epoxy Resin

Abstract

Boron nitride nanosheet (BNNS) decorated with cobalt ferrite nanoparticle (CFN) to afford CFN-BNNS nanohybrid was prepared via a simple hydrothermal route and was well characterized. Subsequently, the as-prepared CFN-BNNS nanohybrid was incorporated into epoxy resin (EP) with the introduction of a weak rotary magnetic field to achieve order orientation, in order to reduce the fire risk and toxic hazards using enhanced shielding effect of BNNS upon combustion. Findings demonstrate that the CFN-BNNS nanohybrid is composed of CFN nanoparticle uniformly dispersed on BNNS surface. Thermal analysis and cone calorimeter data show that the CFN-BNNS nanofiller among EP matrix contributes to improving the char residues and mechanical properties of EP and reducing its fire risk as well as toxic hazards, especially the ordered one is advantageous over the disordered one in reducing the fire risk and toxic hazard. This is because, on the one hand, the orderly aligned BNNS as the physical barrier can more effectively prevent the transfer and diffusion of oxygen and heat. On the other hand, CFN can catalyze the degradation of EP to afford excessive chars on polymer surface; and it is also liable to decomposition during combustion, thereby generating ferrite species to promote EP degradation as well as cobalt species to enhance the oxidation of CO.

Modifying Epoxy Resins to Resist Both Fire and Water

“…From the high magnification SEM image, it is clear that many nanocrystals and nanospheres exist in the condensed phase, which could strengthen the char layers. It is believed that PDMS is decomposed into nanosilica while hydrophobic CoFe 2 O 4 @SiO 2 nanofillers grow during the combustion process; the re-growth CoFe 2 O 4 and nanosilica could promote the formation of the proactive char layers on the surface of the polymer, which exchange the path of heat and oxygen to enhance thermal stability …”

“…It is believed that PDMS is decomposed into nanosilica while hydrophobic CoFe 2 O 4 @ SiO 2 nanofillers grow during the combustion process; the regrowth CoFe 2 O 4 and nanosilica could promote the formation of the proactive char layers on the surface of the polymer, which exchange the path of heat and oxygen to enhance thermal stability. 32 The components of the char of EP after combustion were detected by XRD analysis, with the aim of further understanding the potential mechanism of the flame retardant. As shown in Figure 5a, pristine EP presents a broad peak at 2θ of 23°, which belongs to the (002) plane of graphite.…”

3D Printing of Nacre-Inspired Structures with Exceptional Mechanical and Flame-Retardant Properties

“…In comparison, the a-BNs remained closely packed, and no expansion/ porous was observed after the combustibility test (Figures 5(f) and S16). The hundreds of dense layers of a-BNs with a high melting temperature (~2973 °C) are among the main reasons for its outstanding flame-retardant property [2,45]. The anisotropic thermal conductivity also contributes to the heat-shielding through the redirection of heat flow in the plane direction (Figure 5(d)).…”

Core-Shell Graphitic Carbon Nitride/Zinc Phytate as a Novel Efficient Flame Retardant for Fire Safety and Smoke Suppression in Epoxy Resin

“…The heat release rate (HRR) and total heat release (THR) are an important index for assessing the fire hazards, as shown in Figure 5a,b and Table 2. HRR curves show that: there were two obvious peaks in EP, the first peak corresponds to the decomposition of EP chain; the second peak corresponds to the further decomposition of char [25]. The peak heat release rate (PHRR) values of g-C3N4-EP and g-C3N4/PAZn-EP decreased from 1458.14 kW/m 2 (pure EP) to 906.28 and 417.26 kW/m 2 , which were 37.85% and 71.38% lower than pure EP,…”