Characterization of commercial expandable graphite fire retardants

Focke, Walter Wilhelm; Badenhorst, Heinrich; Mhike, Washington; Kruger, Hermanus Joachim; Lombaard, Dewan

doi:10.1016/j.tca.2014.03.021

Cited by 60 publications

(57 citation statements)

References 38 publications

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“…Indeed, EG has a physical "worm" expansion due to the expansion of graphite, caused by the sublimation of inserted compounds trapped between the graphite layers. [12][13][14][15] On the opposite, ATH dehydrates endothermally upon heating coupled with a dilution effect (water evolution into the gas phase) and the formation of ceramic-like residue (alumina) acting as protective layer. 16 Four materials were prepared ( Table 1).…”

Section: Processingmentioning

confidence: 99%

Additive manufacturing of fire‐retardant ethylene‐vinyl acetate

Geoffroy

Samyn

Jimenez

et al. 2019

Polymers for Advanced Techs

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Thermocompression (with also extrusion and injection molding) is a classical polymer shaping manufacturing, but it does not easily allow designing sophisticated shapes without using a complex mold, on the contrary to 3D printing (or polymer additive manufacturing), which is a very flexible technique. Among all 3D printing techniques, fused deposition modeling is of high potential for product manufacturing, with the capability to compete with conventional polymer processing techniques. This is a quite low cost 3D printing technique, but the range of filaments commercially available is limited. However, in some specific 3D printing processes, no filaments are necessary. Polymers pellets feed directly the printing nozzle allowing to investigate many polymeric matrices with no commercial limitation. This is of high interest for the design of flame‐retarded materials, but literature is scarce in that field. In this paper, a comparison between thermocompression and 3D printing processes was performed on both neat ethylene‐vinyl acetate (EVA) copolymer and EVA flame retarded with aluminum triHydroxyde (ATH) containing different loadings (30 or 65 wt%) and with expandable graphite (EG), ie, EVA/ATH (30 wt%), EVA/ATH (65 wt%), and EVA/EG (10 wt%), respectively. Morphological comparisons, using microscopic and electronic microprobe analyses, revealed that 3D printed plates have lower apparent density and higher porosity than thermocompressed plate. The fire‐retardant properties of thermocompressed and 3D printed plates were then evaluated using mass loss calorimeter test at 50 kW/m2. Results highlight that 3D printing can be used to produce flame‐retardant systems. This work is a pioneer study exploring the feasibility of using polymer additive manufacturing technology for designing efficient flame‐retarded materials.

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Section: Processingmentioning

confidence: 99%

Additive manufacturing of fire‐retardant ethylene‐vinyl acetate

Geoffroy

Samyn

Jimenez

et al. 2019

Polymers for Advanced Techs

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“…(19) These commercial additives were fabricated by treating natural graphite flakes with oxidants such as nitric acid and potassium permanganate in the presence of sulfuric acid.…”

Section: Characterizationmentioning

confidence: 99%

Cone calorimeter study of polyethylene flame retarded with expandable graphite and intumescent fire-retardant additives

Kruger

Focke

Mhike

et al. 2014

Journal of Fire Sciences

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Polyethylene was flame retarded with an intumescent flame retardant at 27 wt.% and expandable graphite at 10 wt.% either on its own or in combination with 10 wt.% or 20 wt.% of the intumescent. Two grades of each flame retardant type were used. They differed primarily with respect to the onset temperature for exfoliation (commercially sourced expandable graphite types) or decomposition (intumescents). The latter were the highdecomposition-onset-temperature intumescent 3,5-diaminobenzoic acid phosphate and the commercially available low-decomposition-onset-temperature ethylenediamine phosphate. The fire performance of pressed sheets with a nominal thickness of 3.2 mm was tested in a cone calorimeter at a radiant flux of 35 kW m 2 . The best char yields were obtained with compositions containing 3,5-diaminobenzoic acid phosphate. Despite this, the best fire overall performance was realized using ethylenediamine phosphate, together with the lowexfoliation-onset-temperature expandable graphite. Formulations based on this intumescent compound ignited later, reached the peak heat release rate earlier, and also burned longer irrespective of the expandable graphite grade used. This can be attributed to the formation, at the burning surface, of a more cohesive char with better thermal and mass transfer barrier properties. This explains why compositions based on ethylenediamine phosphate as intumescent outperformed those containing 3,5-diaminobenzoic acid phosphate in terms of the peak heat release rate and other important fire indices.

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“…A comprehensive characterization of the commercial EG was previously reported . This flame retardant additive was fabricated by treating natural graphite flakes with an oxidant in the presence of sulfuric acid.…”

Section: Resultsmentioning

confidence: 99%

“…The expansion onset temperature, as determined by thermomechanical analysis, was approximately 225 °C. The EG released a mixture of carbon dioxide, carbon monoxide, and sulfur dioxide during the exfoliation process .…”

Section: Resultsmentioning

confidence: 99%

“…It would appear that the presence of the EG destabilized the polymer. The EG features highly oxidized graphene sheets, which contain many different oxygen‐containing functional groups that could facilitate oxidation of the polymer . However, beyond approximately 410 °C, all compounds showed a lower mass loss than the neat black pigmented polyethylene.…”

Section: Resultsmentioning

confidence: 99%

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Thermal properties of polyethylene flame retarded with expandable graphite and intumescent fire retardant additives

et al. 2016

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Summary Low‐density polyethylene was flame retarded by combinations of expandable graphite with either ethylenediamine phosphate or 3,5‐diaminobenzoic acid phosphate. Cone calorimeter, laser pyrolysis, and open flame exposure tests (supported by video and infrared camera data capture and analysis) were conducted to assess ignition and burn behavior. Cone calorimeter results indicated substantial reductions in the peak heat release rates for all flame‐retarded samples but with reduced ignition times and increased flame out times. Smoke generation was suppressed in the presence of expandable graphite. Infrared and video data from open flame fire tests indicated cohesive bonding of expanded strings and thermal shielding properties in all binary systems. All binary systems delivered fire retardation exceeding any of the single fire retardant compounds. They were also able to withstand higher temperatures before ignition, burn through, or sag occurred. All ethylenediamine phosphate‐containing binary systems prevented sample burn through, maintaining structural integrity of samples until eventual melting of the polymer media occurred. Thermogravimetric analysis laser pyrolysis results confirmed the good thermal shielding imparted by the intumescent additives. Copyright © 2016 John Wiley & Sons, Ltd.

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Characterization of commercial expandable graphite fire retardants

Cited by 60 publications

References 38 publications

Additive manufacturing of fire‐retardant ethylene‐vinyl acetate

Additive manufacturing of fire‐retardant ethylene‐vinyl acetate

Cone calorimeter study of polyethylene flame retarded with expandable graphite and intumescent fire-retardant additives

Thermal properties of polyethylene flame retarded with expandable graphite and intumescent fire retardant additives

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