Synthesis of novel phosphonium bromide‐montmorillonite nanocompound and its performance in flame retardancy and dielectric properties of epoxy resins

Abstract

To enhance the flame retardancy of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) on epoxy resins (EPs), by addition reaction with allyltriphenylphosphonium bromide (ATPB), a novel DOPO‐containing phosphonium bromide (DOPO‐ATPB) was synthesized and its structure was characterized by Fourier transform infrared (FTIR), 13C nuclear magnetic resonance (NMR), and X‐ray photoelectron spectroscopy (XPS). By intercalating DOPO‐ATPB into montmorillonite (MMT) layers and with the help of solvents, the intercalated nanocompound (DPAB‐MMT) was prepared, and X‐ray diffraction (XRD) confirmed a d‐spacing expansion of DPAB‐MMT layers (from ~1.01 to ~2.10 nm). The epoxy composites with DOPO‐ATPB and DPAB‐MMT were prepared, and their effects on the flame retardancy, mechanical and dielectric properties were studied by limiting oxygen index (LOI), UL‐94 vertical burning test, cone calorimetry, three‐point bend testing, and the impedance analyzer. The results show that DOPO‐ATPB endows EPs with excellent flame retardancy and dielectric properties, and DPAB‐MMT can be well dispersed in EPs. Compared with pure EP, the EP/8 wt% DOPO‐ATPB increased the LOI values from 23.0% to 32.5%, achieved V‐0 rating and decreased the peak heat release rate (p‐HRR) by approximately 36.6%. With the 8 wt% DPAB‐MMT, the LOI values of epoxy composite was increased from 23.0% to 35.9%, the p‐HRR was decreased by ~25.4%, the mechanical flexural strength was enhanced by approximately 13.4% and the dielectric loss (ε″) was decreased from 0.080 to 0.052 at 100 Hz.

Flame retardancy, dielectric performance, pyrolysis behavior of epoxy resin and cyanate ester composites containing a multifunctional flame retardant

“…Consequently, as the frequency increases, the polarizability of the composites decreases, leading to a reduction in the D k . Additionally, the dipoles in a state of relaxation can hinder the establishment of steering polarization, and cause a reduction steering polarization 28 . Hence, the reduction in the D f value of EPCE and EPCE/8DSF may be ascribed to a decrease in dipolar steering polarization, which leads to a reduction in the dissipation of electric field energy.…”

“…Consequently, as the frequency increases, the polarizability of the composites decreases, leading to a reduction in the D k . Additionally, the dipoles in a state of relaxation can hinder the establishment of steering polarization, and cause a reduction steering polarization 28. Hence, the reduction in the D f value of EPCE and EPCE/8DSF may be ascribed to a decrease in dipolar steering polarization, which leads to a reduction in the dissipation of electric field energy.As illustrated in Figure4, the D k and D f values of EPCE at 10 MHz are 3.78 and 0.01105, respectively, whereas the D k and D f values of EPCE/8DSF composite are 3.58 and 0.00744, respectively, representing a reduction of 5.29% and 29.95% compared to EPCE.…”

Fully aminated rigid‐rod aromatic polyamide efficiently reinforces tetraglycidyl diamino diphenyl methane epoxy resin and its carbon fiber composite

“…Epoxy resin (EP) is a widely employed thermosetting polymer material. [9][10][11] Thus, the modification of EP has been addressed extensively, such as adding functional particles to improve the thermal conductivity, 12 electrical conductivity 13 and flame resistance, 14,15 adding CNTs, 16 nano-clays, 17,18 inorganic alumina, 19,20 graphene oxide, [21][22][23] functionalized aramid nanofibers (fANFs), 24,25 pyrolyzed carbon black, 26 and other hybrid fillers 27,28 to enhance its comprehensive mechanical properties. Our previous studies have shown that the aminated PPTA can significantly strengthen and toughen triglycidyl-p-aminophenol (TGPAP) epoxy resin and its carbon fiber composite, and having little effect on the T g of EP.…”

Bio-Inspired Iron-Loaded Polydopamine Functionalized Montmorillonite as an Environmentally Friendly Flame Retardant for Epoxy Resin

“…As a kind of inorganic filler, montmorillonite (MMT) has the advantages of small size, high thermal stability and high intercalation capacity [ 17 ], which has received special attention in the field of flame retardants [ 18 , 19 ]. MMT can generate SiO 2 and other substances to cover the surface layer during the combustion process, playing a role in protecting the underlying resin matrix from further damage [ 20 , 21 ]. Meanwhile, MMT can also help to reduce the release rate of smoke, heat, and toxic gases during the combustion process [ 22 , 23 ].…”