What are the characteristics of expandable graphite after heating into expandable graphite?

      The expansion characteristics of expandable graphite sheet are different from other expansion agents. When heated to a certain temperature, the expandable graphite begins to expand due to the decomposition of compounds absorbed in the interlayer lattice, which is called the initial expansion temperature. It expands completely at 1000 ℃ and reaches the maximum volume. The expansion volume can reach more than 200 times of the initial value. The expanded graphite is called expanded graphite or graphite worm, which changes from original flake shape to worm shape with low density, forming a very good thermal insulation layer. Expanded graphite is not only a carbon source in the expansion system, but also an insulating layer. It can effectively insulate heat. In fire, it has the characteristics of low heat release rate, small mass loss and less flue gas.

What are the characteristics of expandable graphite after heating into expandable graphite?

Characteristics of expanded graphite

① Strong pressure resistance, flexibility, plasticity and self lubrication;

② Strong resistance to high, low temperature, corrosion and radiation;

③ Extremely strong seismic characteristics;

④ Extremely strong conductivity;

⑤ Strong anti-aging and anti distortion properties.

⑥ It can resist the melting and penetration of various metals;

⑦ It is non-toxic, does not contain any carcinogens and does no harm to the environment.

Several development directions of expanded graphite are as follows:

1. Expanded graphite for special purposes

Experiments show that graphite worms have the function of absorbing electromagnetic waves. The expanded graphite must meet the following requirements: (1) low initial expansion temperature and large expansion volume; (2) The chemical properties are stable, stored for 5 years, and the expansion ratio basically does not decay; (3) The surface of expanded graphite is neutral and has no corrosion to cartridge case.

2. Granular expanded graphite

Small particle expanded graphite mainly refers to 300 mesh expandable graphite with an expansion volume of 100ml / g. This product is mainly used for flame retardant coatings, which is in great demand.

3. Expanded graphite with high initial expansion temperature

The initial expansion temperature of expanded graphite with high initial expansion temperature is 290-300 ℃, and the expansion volume is ≥ 230ml / g. This kind of expanded graphite is mainly used for flame retardant of engineering plastics and rubber.

4. Surface modified graphite

When expanded graphite is used as flame retardant material, it involves the compatibility between graphite and other components. Due to the high mineralization of graphite surface, it is neither lipophilic nor hydrophilic. Therefore, the surface of graphite must be modified to solve the problem of compatibility between graphite and other components. It has been proposed to whiten the graphite surface, that is, to cover the graphite surface with a solid white film, which is a difficult problem to solve. It involves membrane chemistry or surface chemistry. The laboratory may be able to do so, and there are difficulties in industrialization. This kind of white expandable graphite is mainly used as flame retardant coating.

5. Low initial expansion temperature and low temperature expanded graphite

This kind of expanded graphite starts to expand at 80-150 ℃, and the expansion volume reaches 250ml / g at 600 ℃. The difficulties in preparing expandable graphite meeting this condition are: (1) selecting appropriate intercalation agent; (2) Control and mastery of drying conditions; (3) Determination of moisture; (4) Solution of environmental protection problems.