Synergistic effect of layered melamine-phytate and intumescent flame retardant on enhancing fire safety of polypropylene
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Synergistic effect of layered melamine‑phytate and intumescent flame retardant on enhancing fire safety of polypropylene Yuanyuan Zhan1 · Bihe Yuan1 · Sheng Shang1 Received: 10 February 2020 / Accepted: 4 September 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract The possibility of layered melamine-phytate (MEL-PA) as an efficient synergist for intumescent flame retardant (IFR) is explored. The synergistic effects of MEL-PA on polypropylene (PP)/IFR composites are investigated in terms of flammability tests and combustion under forced-flaming condition. The addition of MEL-PA can effectively improve limited oxygen index (LOI) of PP composites. When 2 mass% MEL-PA is incorporated, the LOI value is enhanced from 33.0 to 35.1%. In addition, fire-retardant performance is increased with the addition of MEL-PA. The heat and smoke releases of PP/IFR are greatly reduced by MEL-PA. When IFR is partially replaced by 0.5, 1.0 and 2.0 mass% MEL-PA, total smoke production values are decreased by 27.2%, 34.8% and 57.6%, respectively. Raman spectra analysis indicates that the adding of MEL-PA results in higher graphitization degree of char layer. This work proves that MEL-PA and IFR have a good synergistic effect on flame-retardant PP. Keywords Polypropylene · Intumescent flame retardant · Thermal decomposition · Synergist
Introduction Polypropylene (PP), as one of the most important thermoplastic resins, is widely used in various fields, such as automotive parts, furniture and building materials, owing to its easy processing, excellent mechanical properties and corrosion resistance characteristics [1–3]. Virgin PP is highly flammable with a low limiting oxygen index (LOI) and burns rapidly after ignition. In addition, a lot of heat will be generated during combustion process, accompanying by melt dripping. These disadvantages greatly limit the application of PP. Thus, it will be great significance to expand the application scope by improving flame retardancy of PP [4–8]. In recent years, halogen-based flame retardants have been gradually superseded by intumescent flame retardants (IFRs), due to development of safety and environmental protection awareness [9–14]. IFRs have the advantages of low smoke, low toxic and anti-dripping, which make them considered to be the most promising halogen-free flame retardants [15–19]. Generally, conventional IFR is the * Bihe Yuan [email protected] 1
School of Safety Science and Emergency Management, Wuhan University of Technology, Wuhan 430070, China
mixed components of acid source, charring agent and blowing agent [20]. The most famous IFR formulation contains ammonium polyphosphate (APP), pentaerythritol (PER) and melamine (MEL). Although this IFR system of APP-PERMEL has considerable flame-retardant properties, it also has some drawbacks such as large dosage, weak water resistance and poor compatibility with polymer matrix [15, 19, 21, 22]. For the past few decades, various synergists have been developed to improve flame-retardant properties of IFRs [23–31]. Among them, nanom
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