Study on fire retardant mechanism of nano-LDHs in intumescent system

Abstract

This paper investigated the fire-retardant mechanism of the nano-LDHs in the intumescent system by the temperature programmed oxidation (TPO). Researches were also conducted to explore the function of the nano-LDHs in the composite fire-retardant agents in air and nitrogen atmosphere, respectively. The results indicated that the nano-LDHs species were responsible for the catalytic oxidation of the rich-carbon compound in oxygen atmosphere. In addition, the nano-LDHs species and their calcinated products at high temperature could increase the carbonaceous residue-shield of the carbon-rich materials, improve the quality and the graphitization degree of the formed char-layer, and accelerate the intumescence and expansion of the melting carbon-rich materials to a certain degree under the oxygen-free condition, leading to the carbonization and expansion of the intumescent layer.nanometer, layer double hydroxides (LDHs), fire-retardant mechanism, intumescent system Since the layered double hydroxides (LDHs) were firstly published to be used as precursors of new catalysts by Miyata S [1] in 1971, many issues on their potential applications were increased year after year. The interstitial layers of LDHs were analogous to the molecular sieve, leading to their direct application to a rigidity support framework for the intumescent coat of the fire-retardant coating with an increasing fire-retardant performance. Moreover, the complex metal oxides, formed by calcination of LDHs at different temperature, exhibited an improvement on the carbonization of intumescent layer of fire-retardant coating in fire. Therefore, the LDHs gradually became an ideal fire-retardant auxiliary agent. It should be noticed that the nanometer layered double hydroxides (nano-LDHs) had received considerable interests owing to their comprehensive applications as fire-retardants in recent years. The thermal stability and thermal degradation process of nano-LDHs were analyzed by Yang W et al. [2][3][4] , and their fire-retardant performance were also investigated by Xu Jianghua et al. [5][6][7] ; however, there were few studies on their fireretardant mechanism. The present work mainly purposed to firstly study the fire-retardant mechanism of nanoLDHs by the temperature programmed oxidation, and investigate their fire-retardant function in the intumescent fire-retardant system. Experimental Reagent and instrumentsThe preparation of the purposed products was carried out on the QM planet-style ball mill (Instrument Factory of Nanjing University). The self-manufactured temperature programmed oxidation (TPO) equipment, whose temperature control was carried out on an AI-708PA artificial intelligence industry adjuster (ÜGU Company), was recorded on the produced gas quantity (Figure 1).

Flame retardant polymer/layered double hydroxide nanocomposites

“…The effects of ZnAl, MgAl, and CaAl LDHs on PS have been reported. Zhang et al 74 evaluated the ame retardant performance of PS on addition of MgAl-CO 3 , the results showed that the LOI value was increased from 19 to 27 at 50 wt% LDH loading, with much less smoke produced compared to pure PS. Costache et al 67 prepared PS/ZnAl-undecenoate LDH nanocomposites and observed a PHRR reduction of 35% at 5 wt% LDH loading.…”

“…In addition, ZnMgAl LDHs provided a higher LOI value and a longer combustion time, indicating that ZnMgAl LDHs have a better ame retardant efficiency in ABS. 75 Apart from the polymers discussed above, many other polymers such as PVC, 74,76 UP, 77 EP, 49,52,78,79 PLA, 80 EPDM, 81 and poly(butyl acrylate-vinyl acetate) (P(BA-VAc)) 82 also have been studied with different LDHs, and all showed enhanced ame retardant properties.…”

“…Carbonate is the rst and the one most extensively investigated, carbonate intercalated LDHs have been shown to be highly efficient in improving the thermal stability and re properties of polymers, with the important parameters such as the PHRR, LOI and UL-94 improved compared to pristine polymers. Zhang et al 74 Inspired by the fact that zinc borate is oen combined with MH or ATH for improved smoke-suppressing properties, Shi et al 89 were the rst to report the use of a Mg 2 Al-borate LDH as a ame retardant ller for EVA. At 60 wt% LDH loading, Mg 2 Alborate showed a ame retardant performance similar to Mg 2 Al-CO 3 , the LOI of EVA was increased from 21 to 29 (Mg 2 Al-borate) and 30 (Mg 2 Al-CO 3 ), respectively.…”

Novel Ti3C2Tx MXene/epoxy intumescent fire‐retardant coatings for ancient wooden architectures

“…In addition, to show the advantage of MXene in the fire‐retardant field, the comparison of flame retardancy of TEIFC with composites utilizing other general inorganic fillers 43–47 was presented in Table 2. Due to the noncombustible functional groups and formed fire‐retardant coating, TEIFC‐3 with MXene exhibited excellent fire‐retardant performance.…”

Ammonium alcohol polyvinyl phosphate intercalated LDHs/epoxy nanocomposites

“…Then, phosphorylated polyvinyl alcohol may react with the LDHs layers and release water molecules to produce bridges between AAPP chains. Wang et al [33] reported that only 1.5 % nanoLDHs could catalyze the esterification reaction between ammonium polyphosphate and pentaerythritol. The formation of a small number of such bridges will induce a stabilization of AAPP and a decrease in the volatility of phosphorus, and thus, more AAPP will be available for phosphorylation and char formation [34].…”