Synthesis of Mesoporous Silica@Co–Al Layered Double Hydroxide Spheres: Layer-by-Layer Method and Their Effects on the Flame Retardancy of Epoxy Resins

Jiang, Shanqun; Bai, Zhenghe; Tang, Gang; Song, Lei; Stec, Anna A.; Hull, T. Richard; Hu, Yuan; Hu, Weizhao

doi:10.1021/am503412y

Cited by 146 publications

(79 citation statements)

References 57 publications

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“…This is because the surface of SiO 2 has many silanol groups which can be used as Brønsted acid sites with a role of catalytic degradation of polymers. 16,30 In addition, ZIF-8 contains Zn, and Zn as one of the transition metal elements has an effect on catalyzing the degradation of polymer.…”

Section: Characterization Of Ep and Ep Compositesmentioning

confidence: 99%

“…The rst stage is due to the physical adsorption of water and solvent (room temperature-110 C), the second stage is due to the polycondensation of the structure of the silica network (110-220 C), and the third stage is attributed to the condensation and dehydration of silanol groups (220-360 C). 16,26,27 The weight loss of ZIF-8 also has three stages. The rst stage is the evaporation of the methanol molecules adsorbed on the surface of ZIF-8 below 100…”

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confidence: 99%

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Zeolitic imidazolate framework-8 was coated with silica and investigated as a flame retardant to improve the flame retardancy and smoke suppression of epoxy resin

Wang

Liu

et al. 2018

RSC Adv.

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A material (ZIF-8@SiO 2 ) with a nuclear shell structure was synthesized to improve the flame retardancy and smoke suppression of epoxy resin (EP) through a synergetic catalytic effect. Zeolitic imidazolate framework-8 (ZIF-8) was synthesized and its surface was coated with SiO 2 by hydrolyzing tetraethyl orthosilicate. Core-shell structured ZIF-8@SiO 2 was obtained. Then ZIF-8@SiO 2 was added to EP to explore its effect of flame retardancy and smoke suppression on the EP composite. The results of a cone calorimeter test showed that the peak heat release rate, total heat release, smoke production rate and total smoke production of the material were decreased by 75.9%, 38.9%, 51.1% and 39.8%, respectively, after 2 wt% ZIF-8@SiO 2 was added to EP. Besides, through the analysis of char residue, the mechanism of ZIF-8@SiO 2 /EP's flame retardancy and smoke suppression was determined to be due to the physical barrier effect of SiO 2 and the co-effect of SiO 2 and ZnO decomposition by ZIF-8. IntroductionMetal-organic frameworks (MOFs) are porous materials comprising metal ions and organic bridging ligands.1 ZIF-8 is a metal-organic framework material with a rhombic dodecahedral structure and is synthesized in organic solvent with zinc ions and 2-methylimidazolate.2 Because ZIF-8 has a high specic surface area, high thermal stability and unique pore structure, it is widely applied in adsorption, catalysis, separation, gas storage and drug delivery.3-8 Due to the diversity of nanometer ZIF-8 materials, their new functions are being explored. Therefore, the application of ZIF-8 as a ame retardant has also attracted attention. For instance, Shi et al. prepared ZIF-8/PLA composite materials, and their research indicated that the oxygen index of the composite could reach 26.0% when 3 wt% ZIF-8 was added. The application of ZIF-8 as a new ame retardant is worthy of further exploration.In recent years, the application of silicon-containing compounds in ame retardants has been investigated by many researchers because they not only improve the ame retardant performance, but also form environment-friendly ame retardants.10 The combustion of silicon-containing polymer composites may produce SiO 2 which is easy to migrate and accumulate to the polymer surface, and generate Si-O-Si networks inside the char layer structure and ceramic-like protective material on the substrate surface to prevent the polymer's further burning and protect internal polymer. In addition, some compounds containing Si-C structure are also produced, which enhance the thermal stability of composite materials and increase the strength of the char layer.11-13 Meanwhile, SiO 2 decomposed by silicon-containing compounds is a solid acid with more acidic sites, which can catalyze the degradation of polymers and have a good co-effect of ame retardancy with metal oxides. 14 According to existing literature, 15 the use of SiO 2 coated brucite as a ame retardant has a better effect of ame retardancy compared with the simple physical mixing of SiO 2 and brucit...

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Section: Characterization Of Ep and Ep Compositesmentioning

confidence: 99%

mentioning

confidence: 99%

Zeolitic imidazolate framework-8 was coated with silica and investigated as a flame retardant to improve the flame retardancy and smoke suppression of epoxy resin

Wang

Liu

et al. 2018

RSC Adv.

View full text Add to dashboard Cite

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“…Moreover, but reducing the volatile evolution, the amount of toxic effluent is reduced, and for a given ventilation rate, the ventilation condition becomes more well-ventilated, also reducing the toxicity. Char formation has been enhanced in polyethylene, using functionalised graphene oxide [87]; in PMMA using graphene oxide and a nickel-aluminium layered double hydroxide [88]; in ABS copolymer, with graphene nanosheets combined with a metal hydroxide [89]; in polyamide 6 using graphene supported cobalt oxide and nickel oxide [90]; and in epoxy resins using silica, attached to cobalt-aluminium layered double hydroxide spheres [91]. Enhancement of the barriers can be achieved in intumescent systems, where gas is released within the molten polymer, causing significant swelling, and so increasing the effectiveness of the thermal barrier [92], for example in polyethylene [93], polypropylene [94] and polystyrene [95].…”

Section: Fire Retardantsmentioning

confidence: 99%

Fire toxicity – The elephant in the room?

Stec

2017

Fire Safety Journal

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Fire toxicity is the largest cause of death and injury from unwanted fires, yet it is the least well studied area of fire science and engineering. Fire toxicity increases by factors up to 50, as the fire becomes underventilated. This has proved difficult, but not impossible, to replicate in a controlled way on a bench-scale. Clear correlations have been observed between the stoichiometric equivalence ratio, and the yields of the major asphyxiants, carbon monoxide and hydrogen cyanide. In addition, irritant components of fire effluents, which have an instantaneous effect, can incapacitate fire victims, trapping them in a fire. However, the longer term toxicants present in fire effluents, such as the carcinogenic polycyclic aromatic hydrocarbons, and the microscopic particulates which result from their agglomeration are probably responsible for hundreds or thousands more deaths than the acute asphyxiants and irritants.

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“…On the contrary, the decomposition temperature of PP-20%LDH is 477 • C, which is decreased compared with PP-5%LDH and PP-10%LDH. The reason is that when the Ni 0.2 Mg 2.8 Al-LDH loading increases to 20 wt %, a lot of metal and metal oxide in turn accelerated the catalytic degradation of PP on heating [56,57].…”

Section: Combustion Behavior Of Compositesmentioning

confidence: 99%

Thermal Stability, Combustion Behavior, and Mechanical Property in a Flame-Retardant Polypropylene System

2017

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Abstract:In order to comprehensively improve the strength, toughness, flame retardancy, smoke suppression, and thermal stability of polypropylene (PP), layered double hydroxide (LDH) Ni 0.2 Mg 2.8 Al-LDH was synthesized by a coprecipitation method coupled with the microwave-hydrothermal treatment. The X-ray diffraction (XRD), morphology, mechanical, thermal, and fire properties for PP composites containing 1 wt %-20 wt % Ni 0.2 Mg 2.8 Al-LDH were investigated. The cone calorimeter tests confirm that the peak heat release rate (pk-HRR) of PP-20%LDH was decreased to 500 kW/m 2 from the 1057 kW/m 2 of PP. The pk-HRR, average mass loss rate (AMLR) and effective heat of combustion (EHC) analysis indicates that the condensed phase fire retardant mechanism of Ni 0.2 Mg 2.8 Al-LDH in the composites. The production rate and mean release yield of CO for composites gradually decrease as Ni 0.2 Mg 2.8 Al-LDH increases in the PP matrix. Thermal analysis indicates that the decomposition temperature for PP-5%LDH and PP-10%LDH is 34 • C higher than that of the pure PP. The mechanical tests reveal that the tensile strength of PP-1%LDH is 7.9 MPa higher than that of the pure PP. Furthermore, the elongation at break of PP-10%LDH is 361% higher than PP. In this work, the synthetic LDH Ni 0.2 Mg 2.8 Al-LDH can be used as a flame retardant, smoke suppressant, thermal stabilizer, reinforcing, and toughening agent of PP products.

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Synthesis of Mesoporous Silica@Co–Al Layered Double Hydroxide Spheres: Layer-by-Layer Method and Their Effects on the Flame Retardancy of Epoxy Resins

Cited by 146 publications

References 57 publications

Zeolitic imidazolate framework-8 was coated with silica and investigated as a flame retardant to improve the flame retardancy and smoke suppression of epoxy resin

Zeolitic imidazolate framework-8 was coated with silica and investigated as a flame retardant to improve the flame retardancy and smoke suppression of epoxy resin

Fire toxicity – The elephant in the room?

Thermal Stability, Combustion Behavior, and Mechanical Property in a Flame-Retardant Polypropylene System

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