A novel intumescent flame retardant imparts high flame retardancy to epoxy resin

Abstract

Intumescent flame retardant (IFR) has received the considerable attention ascribed to the inherent advantages including non-halogen, low toxicity, low smoke release and environmentally friendly. In this work, a novel charring agent poly (piperazine phenylaminophosphamide) named as PPTA was successfully synthesized and characterized by Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS). Then, a series of flame-retardant EP samples were prepared by blending with ammonium polyphosphate (APP) and PPTA. Combustion tests include oxygen Index (LOI), verticalBurning Test (UL-94) and cone calorimeter testing，these test results showed that PPTA greatly enhances the flame retardancy of EP/APP. According to detailed results, EP containing 10 wt% APP had a LOI value of 30.2%，but had no enhancement on UL-94 rating.However, after both 7.5 wt% APP and 2.5 wt% PPTA were added, EP-7 passed UL-94 V-0 rating with a LOI value of 33.0%. Moreover, the peak heat release rate (PHRR) and peak of smoke product rate (PSPR) of EP-7 were greatly decreased. Meanwhile, the flameretardant mechanism of EP-7 was investigated by scanning electron microscopy (SEM), thermogravimetric analysis/infrared spectrometry (TG-IR) and X-ray photoelectron spectroscopy (XPS). The corresponding results presented PPTA significantly increased the density of char layer, resulting in the good flame retardancy. K E Y W O R D Sepoxy resin, flame retardancy, mechanism, thermal behavior

Impact on flame retardancy and degradation behavior of intumescent flame‐retardantEPcomposites by a hyperbranched triazine‐based charring agent

“…27,36 It was seen from the N1s XPS spectra that the signals at 398.7 eV, 400.1 and 401.6 eV were assigned to the C N or P N, N C and N H groups, respectively. 6 The relative content of N H bonds in EP-IFR at 401.6 eV was significantly lower than that in EP-APP just validated the speculation of nitrogen conversion to N 2 or NH 3 . As seen from Figure 7, the XPS spectra of P2p presented two characteristic peaks at 133.8 and 134.7 eV, which belonged to the P O/PO 3 groups in pyrophosphate or polyphosphate compounds and P O C group, respectively.…”

“…The proportion of O groups in EP‐IFR residues (69.8%) was higher than that in EP‐APP (65.8%), indicating that the combination of HTCFA promoted the formation of more crosslinked structures in condense phase during burning 27,36 . It was seen from the N1s XPS spectra that the signals at 398.7 eV, 400.1 and 401.6 eV were assigned to the CN or PN, NC and NH groups, respectively 6 . The relative content of NH bonds in EP‐IFR at 401.6 eV was significantly lower than that in EP‐APP just validated the speculation of nitrogen conversion to N 2 or NH 3 .…”

“…IFR mainly composed of acid source (dehydrating agent or carbonation promoter), gas source (foaming agent or nitrogen source) and carbon source (carbon forming agent). 6 During fire, the carbon forming agent in the IFR was dehydrated under the action of carbonation promoter to form carbides. Then expanded carbon residues by foaming agent were generated preventing the transfer of oxygen/ heat, thus interrupting the fire behavior.…”

“…Intumescent flame retardant (IFR) have attracted much attention as a typical halogen‐free flame retardant because of its low smoke, low toxicity, high thermal stability and carbon formation rate, and good compatibility with the environment. IFR mainly composed of acid source (dehydrating agent or carbonation promoter), gas source (foaming agent or nitrogen source) and carbon source (carbon forming agent) 6 . During fire, the carbon forming agent in the IFR was dehydrated under the action of carbonation promoter to form carbides.…”

POSS‐modified ammonium polyphosphate for improving flame retardant of epoxy resins

“…For instance, ammonium polyphosphate (APP) is an important phosphorus flame retardant for epoxy resins, 13 but it is not an effective flame retardant when it is used alone as it is not enough to form a rich char having a flame retardant effect. To overcome this shortcoming, much research has been conducted over the last several decades such as microencapsulation with char forming agent, and surface modification 14,15 via silane coupling agent 16 or other char forming agent 17 . MingYuan Shen et al 18 used 4,4′‐oxydiphenylamine formaldehyde (OF) resin as the microcapsule shell as a char forming agent to coat APP utilizing in‐situ polymerization technology.…”