Synthesis of LDHs Based on Fly-Ash and Its Influence on the Flame Retardant Properties of EVA/LDHs Composites

Shaoquan Li; Xiao-Dong Zhu; Long Li; Yi Qian; Qingjie Guo; Jingjing Ma

doi:10.3390/polym14132549

Synthesis of LDHs Based on Fly-Ash and Its Influence on the Flame Retardant Properties of EVA/LDHs Composites

Polymers (Basel). 2022 Jun 23;14(13):2549. doi: 10.3390/polym14132549.

Authors

Shaoquan Li^{1

2}, Xiao-Dong Zhu¹, Long Li³, Yi Qian¹, Qingjie Guo^{1

4}, Jingjing Ma⁴

Affiliations

¹ School of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, China.
² School of Materials Science and Engineering, Guangdong University of Petrochemical Technology, Maoming 525000, China.
³ School of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, China.
⁴ State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering, Ningxia University, Yinchuan 750021, China.

Abstract

Fly-ash, a kind of large solid waste in energy industry, has brought about serious environmental problems and safety consequences. No efficient way has been found yet to deal with it worldwide. The focus of contemporary research are mainly placed on the reuse of aluminum and iron, but with a low utilization rate less than 30%. Having destroyed the ecological balance, fly-ash has become a challenge drawing the attention of people in the solid waste industry. In this paper, a smoke-suppressant and flame-retardant layered double hydroxide (LDH) featuring Mg-Al-Fe ternary was successfully synthesized by fly-ash after coprecipitation. XRD results presented LDHs successful synthesis. Then, exploration on the flame retarding properties of LDHs in composites composed by ethylene vinyl acetate (hereinafter referred to as EVA)/LDHs was carried out by UL-94, limiting oxygen index (LOI), cone calorimeter (CCT), smoke density (SDT), and thermogravimetry-Fourier transform infrared spectrometry (TG-IR) tests. UL testing results showed that most of the samples had a vertical combustion rating of V-0. LOI results showed the highest LOI value of ELDH-1, amounting to as high as 28.5 ± 0.1 while CCT results showed that the rate of heat releasing, mass loss, and smoke production of composite materials were decreased significantly compared with corresponding data of pure EVA. The ELDH-1 sample displayed the lowest peaks of heat release rate (pHRR) value of 178.4 ± 12.8 Kw·m^-2 and the lowest total heat release (THR) value of 114.5 ± 0.35 KJ·m^-². Then, SDT indicated that under respective ignition and non-ignition conditions, all composite materials present a good smoke suppression performance. Additionally, digital photographs after CCT demonstrated that EVA/LDHs composites could enhance the formation of compact charred layers, and prevent their splitting, which effectively prevent the underlying materials from burning. Finally, TG-IR findings showed that compared with pure EVA, EVA/LDHs composites also achieved a higher-level thermal stability.

Keywords: ethylene-vinyl acetate; flame retardant; fly-ash; layered double hydroxides; smoke suppression; thermal stability.

Abstract

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