Synergistic effects of polyoxometalate‐based ionic liquid‐doped sepiolite in intumescent flame‐retardant high‐density polyethylene

Abstract

A polyoxometalate‐based ionic liquid‐doped sepiolite (SEP‐PIL) was prepared by electrostatically immobilizing phosphomolybdic acid (PMA) on natural sepiolite embedded with imidazolium cations (SEP‐IL), and its structural properties were fully characterized by various methods. Furthermore, a new intumescent flame‐retardant system (IFR) for high‐density polyethylene (HDPE) was constructed by adding SEP‐PIL into conventional HDPE/IFR composites. The retardant properties and thermal decomposition behaviors were comprehensively investigated. The results showed that the HDPE composite containing 24 wt% IFR and 1 wt% SEP‐PIL passed UL‐94V‐0 rating, and the limiting oxygen index increased from 17.8% (pure HDPE) to 27.6%. In addition, the HDPE/IFR/SEP‐PIL composite had lower peak heat release rate (PHRR) and total heat release (THR) compared to the HDPE/IFR composite. The thermogravimetric analysis demonstrated that the combination of SEP‐PIL with IFR could greatly promote the formation of residual chars. Dynamic rheological measurement further confirmed that the synergistic effect of SEP‐PIL and IFR could greatly improve the flame retardancy of HDPE/IFR/SEP‐PIL composites.

Thermally conductive polymer-based composites: fundamentals, progress and flame retardancy/anti-electromagnetic interference design

“…Intumescent flame retardants are mainly composed of phosphorus and nitrogen, including the acid source, carbon source and gas source. 172,173 They can form a porous expanded carbon layer during combustion, which acts as a barrier and protects the internal polymer. The decomposition of the acid source (phosphate, borate and phosphate ester) after heating promotes the dehydration reaction between the carbon source and the polymer matrix to form a carbonization layer.…”

Development of bio‐based magnesium phosphate flame retardant for simultaneously improved flame retardancy, smoke suppression and mechanical properties of HDPE

“…1 However, HDPE is easy to burn and releases toxic gases when burning, so it is an urgent problem to improve the flame retardancy of HDPE materials to improve the safety of high-voltage cable materials. 2 Adding flame retardant is considered to be an effective way to reduce the fire risk of HDPE. With the growth of the global economy, magnesium hydroxide (MH), as a non-toxic and smokeless flame retardant, has attracted much attention due to the environmental concern.…”

“…High‐density polyethylene has the advantages of lightweight, low toxicity, high electrical insulation, good chemical resistance and easy processing, and is used to prepare high‐voltage cable sheaths 1 . However, HDPE is easy to burn and releases toxic gases when burning, so it is an urgent problem to improve the flame retardancy of HDPE materials to improve the safety of high‐voltage cable materials 2 …”

Synthesis of metal‐containing Schiff based cyclomatrix polyphosphazene microspheres based on polyoxometalates and application in flame retardance for epoxy resin

“…11,12 Traditionally, the hybrids were synthesized by different synthetic methods such as physical blending, chemical coating, hydrothermal synthesis and layer-by-layer assembly strategy. [13][14][15][16] However, the flame-retardant impact of metal-containing polymers connected by covalent bonds is rarely studied in polymer matrices.…”