Several development directions of expanded graphite are as follows:
1. Expanded graphite for special purposes
Experiments have shown that graphite worms have the function of absorbing electromagnetic waves. The properties of expanded graphite make it highly valuable for military applications. The U.S. military and our military have both conducted experimental research in this area. This expanded graphite must meet the following requirements: (1) The initial expansion temperature is low and the expansion volume is large; (2) The chemical properties are stable, and the expansion rate will not decay after 5 years of storage; (3) The surface of the expanded graphite is neutral and is resistant to The cartridge case is corrosion-free.
2. Granular expanded graphite
Small particle expanded graphite mainly refers to 300 mesh expandable graphite, its expansion volume is 100ml/g. This product is mainly used for flame retardant coatings, and its demand The portion is huge.
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 type of expanded graphite is mainly used for flame retardant engineering plastics and rubber. This product has been successfully developed by Hebei Agricultural University and applied for a national patent.
4. Surface modified graphite
When expanded graphite is used as a flame retardant material, it involves the issue of compatibility between graphite and other components. Due to the high degree of mineralization on the 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. Someone once proposed to whiten the surface of graphite, that is, to cover the surface of graphite with a solid white film. This is a difficult problem to solve, involving film chemistry or surface chemistry. It is possible to do it in the laboratory, but there are difficulties in industrialization. This type of white expandable graphite is mainly used for flame retardant coatings.
5. Low initial expansion temperature, low-temperature expanded graphite
The temperature at which this type of expanded graphite begins to expand is 80-150°C, and the expansion volume reaches 250ml/g at 600°C. The difficulties in preparing expandable graphite that meets this condition are: (1) Selecting the appropriate intercalation agent; (2) Control and mastering of drying conditions; (3) Determination of moisture; (4) Solving environmental protection issues. Currently, the preparation of low-temperature expandable graphite is still in the experimental stage.