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808121

Sigma-Aldrich

Expandable Graphite

flakes

Synonym(e):

Graphite intercalation compound, Intumescent flake graphite

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2.5 KG
138,00 €

138,00 €

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2.5 KG
138,00 €

About This Item

Lineare Formel:
C24(HSO4)(H2SO4)2
UNSPSC-Code:
12352200
NACRES:
NA.23

138,00 €

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Beschreibung

Expansion Ratio (X:1): 270 to 325

Qualitätsniveau

100

Form

flakes

Partikelgröße

+50 mesh (>300μ, ≥75% minimum)

pH-Wert

5-10

Löslichkeit

water: insoluble

Verwandte Kategorien

Allgemeine Beschreibung

Expandable graphite is a synthesized intercalation compound of graphite that expands or exfoliates when heated. This material is manufactured by treating flake graphite with various intercalation reagents that migrate between the graphene layers in a graphite crystal and remain as stable species.
If exposed to a rapid increase in temperature, these intercalation compounds decompose into gaseous products, which results in high inter-graphene layer pressure. This pressure develops enough force to push apart graphite basal planes in the “c” axis direction. The result is an increase in the volume of the graphite of up to 300 times, a lowering of bulk density, and approximately a 10-fold increase in surface area.

Anwendung

  • Graphene precursor.
  • Inorganic source of carbon.
  • Filler.
  • Thermal additive.
  • Fire retardant additive.
  • Casting powders.
  • Plastic additive.
  • Rubber additive.
  • EMF absorber.
  • Milling and sieving.
  • Bulk loading, unloading.
  • Base material for gaskets and seals.
  • Coatings.

Piktogramme

Health hazard
GHS08

Signalwort

Warning

H-Sätze

H373

Gefahreneinstufungen

STOT RE 2 Inhalation

Zielorgane

Lungs

Lagerklassenschlüssel

13 - Non Combustible Solids

WGK

WGK 1

Flammpunkt (°F)

Not applicable

Flammpunkt (°C)

Not applicable

Hier finden Sie alle aktuellen Versionen:

Analysenzertifikate (COA)

Lot/Batch Number
MKCW1461
MKCR2688
MKCM1803
MKCG3688
MKBX4977V

Die passende Version wird nicht angezeigt?

Wenn Sie eine bestimmte Version benötigen, können Sie anhand der Lot- oder Chargennummer nach einem spezifischen Zertifikat suchen.

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Besitzen Sie dieses Produkt bereits?

In der Dokumentenbibliothek finden Sie die Dokumentation zu den Produkten, die Sie kürzlich erworben haben.

Die Dokumentenbibliothek aufrufen

Siegfried Eigler
Chemical communications (Cambridge, England), 51(15), 3162-3165 (2015-01-22)
Graphite sulphate is used as a precursor to graphene for the first time. The positively charged graphene layers react with water to yield a processable graphene derivative. The unprecedented low density of defects is determined to be 0.06% on average
Electrochemical reactivation of expanded graphite electrodes covered by oligomeric products of phenol electrooxidation.
Krawczyk P, and Skowronski, JM.
Electrochimica Acta, 79, 202-209 (2012)
Nicolas R Tanguy et al.
ChemSusChem, 14(4), 1057-1067 (2020-11-28)
The increasing demand for wearable electronics has driven the development of supercapacitor electrode materials toward enhanced energy density, while being mechanically strong, flexible, as well as environmentally friendly and low-cost. Taking advantage of faradaic reaction of quinone groups in natural
Ayrat M Dimiev et al.
ACS nano, 6(9), 7842-7849 (2012-08-14)
Graphite intercalation compounds (GICs) can be considered stacks of individual doped graphene layers. Here we demonstrate a reversible formation of sulfuric acid-based GICs using ammonium persulfate as the chemical oxidizing agent. No covalent chemical oxidation leading to the formation of

Fragen

1-7 von 7 Fragen  

  1. How is shipping temperature determined? And how is it related to the product storage temperature?

    1 Antwort

    1. Products may be shipped at a different temperature than the recommended long-term storage temperature. If the product quality is sensitive to short-term exposure to conditions other than the recommended long-term storage, it will be shipped on wet or dry-ice. If the product quality is NOT affected by short-term exposure to conditions other than the recommended long-term storage, it will be shipped at ambient temperature. As shipping routes are configured for minimum transit times, shipping at ambient temperature helps control shipping costs for our customers. For more information, please refer to the Storage and Transport Conditions document: https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/marketing/global/documents/316/622/storage-transport-conditions-mk.pdf

      Hilfreich?

  2. How can I determine the shelf life / expiration / retest date of this product?

    1 Antwort

    1. If this product has an expiration or retest date, it will be shown on the Certificate of Analysis (COA, CofA). If there is no retest or expiration date listed on the product's COA, we do not have suitable stability data to determine a shelf life. For these products, the only date on the COA will be the release date; a retest, expiration, or use-by-date will not be displayed.
      For all products, we recommend handling per defined conditions as printed in our product literature and website product descriptions. We recommend that products should be routinely inspected by customers to ensure they perform as expected.
      For products without retest or expiration dates, our standard warranty of 1 year from the date of shipment is applicable.
      For more information, please refer to the Product Dating Information document: https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/marketing/global/documents/449/386/product-dating-information-mk.pdf

      Hilfreich?

  3. Can you tell me the specific surface area and pore volume of this product expandable graphite, available on your website ?

    1 Antwort

    1. The surface area and pore size are not determined for this product.

      Hilfreich?

  4. What is the size of 808121 Sigma-Aldrich Expandable Graphite product?

    1 Antwort

    1. This particle size specification for this product is a minimum of 75% at +50 mesh / 300 um or larger, with the remainder being less than 250 um. The value is lot specific and reported on the product Certificate of analysis. Please see the link below to review a sample or lot specific Certificate:
      https://www.sigmaaldrich.com/product/aldrich/808121#product-documentation

      Hilfreich?

  5. Has the graphite (808121) already undergone expansion through a heating process, or is it necessary to expand the graphite by heating? If heating is required, what kind of heating process should be used?

    1 Antwort

    1. The material in question is considered either Expandable Graphite or Intercalated Graphite. It is sold in its flake form and has not been expanded into worms, which is the industry standard verbiage for expanded graphite.

      There are various methods available for the expansion of this material, but certain questions need to be addressed before providing the most suitable approach. For instance, 1 gram of this material will expand to 270 – 325 ml in volume, and the rate and volume of expansion depend on the change in temperature, also known as the “Delta T”. The material will achieve its maximum expansion with a fast thermal shock.

      The most widely used method for small quantities involves placing a small amount of material on a piece of Graphite Foil and putting that foil in a furnace heated to at least 950°C (about 1750°F). The higher the temperature, the better. Once the expansion visibly stops, the material should be removed from the furnace and allowed to cool. It is important to note that leaving the material in the furnace for an extended period increases the risk of starting an oxidation reaction. However, this procedure releases acidic gases and should only be performed under a fume hood.
      There have been reports of people expanding this material in a microwave, although this method is often incomplete and may result in unexpanded pieces in the product.
      If a large amount (production size amounts) needs to be expanded, the use of a larger furnace and some form of air scrubber, typically some type of caustic soda, is necessary to neutralize the off gas.

      Hilfreich?

  6. How long do you need to heat the expandable graphite at the onset expansion temp? Is there a disadvantage to heating it for a long period?

    1 Antwort

    1. The most widely used method for small quantities is placing a small amount of material on a piece of graphite foil and putting that foil in a furnace heated to at least 950 C (about 1750 F). The higher the temperature the better.
      Once you visibly see the expansion stop, pull that material out of the furnace and allow to cool. There is no specific amount of time recommended. The longer you leave this material in the furnace the better chance you have of starting an oxidation reaction. Be aware, that this procedure causes acidic gasses to be released and advised to only be performed under a fume hood.

      Hilfreich?

  7. What is the onset expansion temperature of this product

    1 Antwort

    1. The most widely used method to check expansion for a small amount of 808121 is placing it on a piece of Graphite Foil and putting that foil in a furnace heated to at least 950 °C (about 1750 °F). The higher the temperature the better. So the onset expansion temp could be 950 °C.

      Hilfreich?

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