Synergistic effects of dual imidazolium polyoxometalates on intumescent flame retardant polypropylene

Abstract

The role of dual imidazolium polyoxometalates (POMs) in the flame retardancy of polypropylene/intumescent flame retardant (PP/IFR) composites was studied. The results showed that the structures of dual imidazolium POMs have a great effect on the flame retardancy of PP composites. The dual imidazolium POMs based on an ethyl group (EMIPMA) obtain the best flame retardant efficiency. With 15.5 wt % IFR and 0.5 wt % EMIPMA, the PP composites reach a limiting oxygen index of 25.7 and the UL‐94 V‐0 standard. However, the dual imidazolium POMs containing a butyl (BMIPMA) or hexyl (HMIPMA) group cannot achieve the UL‐94 V‐0 standard at the same formulation. Dual imidazolium POMs not only promote the formation of good char, but also induce the formation of intumescent char with a hierarchical and microporous structure that helps to prevent gas and heat from transferring from the flame to the resin. Therefore, the flame retardancy of PP/IFR composites is improved. However, excessive combustible components produced by BMIPMA or HMIPMA deteriorate the flame retardancy of PP/IFR composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45491.

Improvement of thermoplastic polyurethane's flame retardancy and thermal conductivity by leaf‐shaped cobalt‐zeolitic imidazolate framework–modified graphene and intumescent flame retardant

“…The char layer can prevent the heat of the radiation cone from going into the polymer and provide a barrier against the internal flammable gas into the flame. 19 The carbon layer limits the rapid increase of the heat release rate, and the HRR curve gradually flattens out after the first peak appears. At the same time, the graphene sheet layer has a physical barrier effect, which can slow down the volatilization of combustible gas.…”

“…18 The synergistic effect of dual imidazolium polyoxometalates (POMs) and intumescent flame retardant is also evident in polypropylene composites. 19 In recent years, zeolitic imidazolate frameworks (ZIFs) containing different metal such as iron, zinc and cobalt has attracted a lot of attention in flame retardant field. 20 Such as the ZIF-8 was used as a flame retardant in polyvinyl alcohol (PVA) and their limiting oxygen index increased from 19.5% to 24.0%.…”

Synergistic flame retardant effect of piperazine salt and ammonium polyphosphate as intumescent flame retardant system for polypropylene

“…[6][7][8][9][10][11][12][13] To overcome these shortcomings, different flame retardants for PP have been developed in the past decades. [14][15][16][17] Recently, IFR has become a hot spot due to its low smoke and high carbon content. [18][19][20][21][22] Generally, a classic IFR system is composed of ammonium polyphosphate (APP), pentaerythritol (PER), and melamine (MEL).…”

Enhanced dispersibility and uniform distribution of iron phosphonate to intensify its synergistic effect on polypropylene‐based intumescent flame‐retardant system

“…To solve this issue, many studies have investigated the synergistic flame-retarded effect by introducing a synergist into IFR/polymer composites. [8][9][10][11][12][13][14][15] The addition of a synergist has usually resulted in the loading of an IFR required decreasing from about 25-30 wt% to about 20-25 wt% to achieve the V-0 rating of UL-94. The greater the effect of the synergist the lower the loading of additives, for example, IFR, needed to achieve the same flame retardancy.…”