
Expandable Graphite
Discover the versatility
of an innovative raw material
In a world where material innovation is driving progress, expandable graphite stands as a remarkable example of the versatility and transformative power of material science. This unique form of graphite, also known as expandable graphite, has attracted the attention of various industries and established itself as an indispensable component of numerous applications.
Expandable graphite differs fundamentally from conventional graphite due to its remarkable ability to expand greatly when heated.
This expansion occurs due to the structure of the graphite, which consists of layers separated by gaps. When these spaces are activated by heat, the material expands rapidly, giving it a porous, lightweight structure. This property predestines the material for use in various fire protection applications.
The production of expandable graphite is a fascinating process that requires careful control and expertise. Based on our many years of experience and a global network, we can offer expandable graphite with properties that are specifically tailored to our customers’ requirements
The areas of application for expandable graphite are as varied as they are impressive. The material is ideal for use in building fire protection.
Expandable graphite is used, for example, in penetration seals for pipes and cables, between firewalls and ventilation systems. Seals with expandable graphite protect doors and windows in the event of fire. In paints and varnishes, expandable graphite provides fire protection for steel beams, for example. Expandable graphite is also used as a fire protection additive in the textile industry. The carpet backings of aircraft carpets or passenger trains contain expandable graphite, as do innovative fire protection jackets. In addition to its use in fire protection applications, the expanding property is also used in other applications, e.g. in metallurgy, where expandable graphite is used in covering powders. By expanding the graphite, the heat/energy is retained for longer.

ADVANTAGES OF RMC
Long-standing partnerships
Thanks to our long-standing partnerships, we benefit from constant further developments, familiar production processes and efficient logistics.
Technical advice
Our many years of experience in the field of technical carbons enable us to provide individual, technical advice based on your application.
Quality control within Germany
The expandable graphites on offer are tested and approved in the German laboratory on a batch-by-batch basis. New developments are also tested and delivery
sources validated on this basis.
rEach compliant, iso 9001:2015, Ecovadis
We ensure REACH compliance for all materials, are ISO 9001:2015 certified and a member of Ecovadis.
Rapid availability
The storage of standard types in the German warehouse enables rapid deliveries. We usually supply our customers on the basis of framework agreements, which are then held in the German warehouse for the long term. This enables flexible, rapid delivery without long delivery times and minimizes logistics risks in worldwide transport.
Further development
We see ourselves as a supply partner who not only supplies existing raw materials, but also develops them further in cooperation with the customer if necessary. We are characterized by the implementation of new ideas and adaptations.
FROM NATURE
Graphite – the natural base
fLAm and BraND protection
Graphite is one of the most natural forms of carbon in its pure form, characterized by the hexagonal crystal lattice system. Gráphein means writing in ancient Greek, from which the name graphite is derived, as graphite leaves the characteristic grey line color on paper or rough surfaces.
It has been used in Europe for centuries and is characterized by its high temperature resistance. In an oxygen-free environment, graphite only sublimates at a temperature of well over 3,000°C. Graphite is resistant to non-oxidizing acids and is an excellent electrical and thermal conductor with anisotropic properties.
The conductivity here is formed along the layers, but not across the layers. Due to the aforementioned hexagonal layer lattice structure and the weak Van der Waals forces between the individual layers, these can not only be easily moved against each other (lubricating property), but also allow the introduction of expanded salts.
With the help of these acid compounds, which are stored between the layers, the material expands many times its original volume when exposed to heat.
Layered grid structure enables unique properties

Heat resistant up to > 3000° C (in =O2-free atmosphere).
Molecules can be embedded between the graphite layers.
These stored bloating salts/
acid compounds expand when exposed to heat.
Enormous increase in volume – up to 500 times the original
volume possible.

FROM GRAPHITE ORE TO EXFOLIATED GRAPHITE

Dismantle
The production process begins with the extraction of natural graphite ore, which is mined. These ores are mined in the known graphite mining areas.
These are mostly located in Asia (China) or on the African continent.

Grinding
The mined ore is crushed and prepared for further processing. This process serves as preparation for the subsequent purification.

Flotation
The crushed ore is purified using flotation (ore + water + flotation agent). Due to the hydrophobic properties of graphite, the graphite can be easily separated from the other mineral components and thus flotated to a purity of up to >95 %. The graphite suspension is then dried for further processing.

Seven
The floated graphite is now sieved into different grain fractions. The raw material for the different types of exfoliated graphite is already classified here.

Cleaning
Depending on the desired purity, the material is further processed by means of chemical purification so that the carbon content can be increased to up to >99 %.
This additional step is not necessary for most of our exfoliated graphite types, as the standard carbon content of >95 % is sufficient without chemical purification.

Intercalation
The main step in the production of expandable graphite is the so-called intercalation process. In various chemical process steps, expanded salts are incorporated into the graphite layer lattice structure (see diagram) with the help of acid compounds
(e.g. H2SO4, HNO3) and oxidizing agents (e.g. KMnO4, H202).
These compounds are firmly bound in the layered lattice structure of the graphite and ensure the desired property of swelling when exposed to heat. The types offered by RMC Remacon are processed without halogens or chromium .
IMPOSSIBLE
IN MANY INDUSTRIES
INDUSTRIES AND APPLICATIONS


Building fire protection
Various types of penetration seals for pipe and cable connections between firewalls and ventilation systems contain expandable graphite.
Seals with expandable graphite protect doors and windows in the event of fire.
Thermal insulation with expandable graphite prevents the uncontrolled spread of fire on facades.

Roofing membranes
In the event of fire, expandable graphite in roofing membranes provides an insulating, foam-like protective layer that delays the penetration of flames and the spread of heat.
In addition, expandable graphite ensures that the roofing membrane retains its structural integrity for longer in the event of a fire.

Fire protection in functional textiles
Both firefighters’ protective equipment and fire curtains can be equipped with expandable graphite.

Seats / carpets / mattresses
Carpet backings in airplanes or passenger trains contain expandable graphite for fire protection, as do mattresses made of polyurethane foam (PU).

E-mobility
Seals and housing components of electric car batteries are equipped with expandable graphite and protect against the uncontrolled spread of fire.

Plastics
Expandable graphite is incorporated into a wide variety of plastics as a fire protection additive. The end applications include polyurethanes, polymers (e.g. PP, PE and PA) and many other plastics with different end applications.
RMC Remacon is also working on solutions for dust-free expandable graphite for smooth processing.

CHARACTERISTICS
Purity
The purity of exfoliated graphite is classified by its carbon content. This is adjusted by means of flotation / chem. Purification (see production). In principle, our expandable graphites are available in the purity levels 90 % – 99 % carbon. As the expansion properties are largely dependent on the selection of the graphite flake (origin / grain size) and the intercalation agent, the carbon content is usually not the main focus when selecting the type. As standard, our expandable graphites have a purity of 95 % – 98 % carbon.

Moisture content
The moisture content of the expandable graphite is typically >1 %. With special processing specifications, this can be reduced to < 0.5 % to < 0.2 % depending on the type

pH value
Our standard types are generally specified with a neutral pH value (5-9). The pH value depends on the manufacturing process and the processing of the material. An acidic expandable graphite pH <4 can indicate poor cleaning of the graphite or the leaching out of expanded salts based on a damaged expandable graphite flake (high shear forces/partitioning of the flake). This can lead to chemical reactions or even corrosion. Please contact us if you require expandable graphite in an alkaline environment. For this we have a variety with pH 9 – 11.

Particle sizes, expansion pressure,
Expansion volume
The three parameters: Grain size, expansion volume and expansion pressure are parameters that are interdependent. Due to the layer lattice structure of graphite, the larger the flake size, the better the expansion properties, as the number of layers then enables greater expansion.
The choice of grain size therefore has a significant influence on the material properties.
Our standard types have a grain size of 80 % >250 µm. The blowing rates here are approx. 250 – 300 times the original volume.
With our coarsest grades, such as BLG 400L) 80 % > 500 µm, we achieve blowing rates of > 450 ml/g.
The expandable graphite with the smallest grain size (BLG40T) has a grain size of 80 % < 75 µm. The expansion here is just40 cm³/g.
In addition to determining the volume increase, the types are also tested with regard to the expansion pressure. These parameters are also dependent on the particle size and can be defined together


Starting temperature
The start temperature defines the temperature at which the process of graphite expansion or swelling begins. We measure the first significant movements in the material here. The expandable graphite expands from this temperature point. It should be noted that this does not happen explosively from the starting point, but requires an increase in the temperature curve. Depending on the type, the complete increase in volume is only achieved at a temperature of 600°C – 1,000°C.
The starting temperature is usually between 180°C – 200°C. We also offer types with lower starting temperatures (130°C – 170°C). In addition, high processing temperatures can mean that expandable graphites with a higher starting temperature are required, e.g. for polymers such as polyamide. For this purpose, we offer expandable graphites with late starting temperatures of up to 290°C.

Remacon standard type overview (typical values)
Standard expandable graphite in different grain sizes
Expandable graphite with high expansion
Expandable graphite with high starting temperature
Expandable graphite with fine grain size
RMC Remacon
Based in Bad Säckingen on the Upper Rhine, RMC Remacon today supplies technical carbons all over the world. Our customers include small and medium-sized companies as well as large global corporations. In the end, our expandable graphite is used to produce a wide variety of flame retardant coatings, fillers for pipe sleeves and cable ducts, additives for PU foams and fire protection additives for the plastics industry. Our consultants have extensive know-how about the possible applications of expandable graphite. We will be happy to advise you on the optimum product for you.
To the contactConsulting & Contact
Do you have questions or need advice?
Please call us or write to us via our contact form.
RMC Remacon GmbH
Hugo-Herrmann-Str. 15
79713 Bad Säckingen
Germany
Phone. +49 7761 939 930
Mail: info@rmc-remacon.com