High purity flake graphite are further processed through a special chemical modification call intercalate process. Chemical is inserted into the spaces between the graphene planes during the Special chemical process. This intercalate process enable processed graphite to expand many times of it original size when under high temperature with an expansion ratio of 100~500ml/g. Its shape would change from flake to worm like, turn flexible and porous with a larger specific surface area and stronger absorption capacity. These worm like graphite could tabling among themselves, which increases their flexibility, rebound elasticity and machinability, so they are excellent material to produce flexible graphite sheet and various kinds of sealing elements. It can also be used as lubricating filler, heat preservation additive for metallurgical industry, battery adsorbent material, halogen free flame-retardant additive and so on.
When subjected to high heat at a range of 150℃ to 200℃, expandable graphite expand or exfoliate suddenly and rapidly to several hundred times of it original volume. In free expansion the final volume can be with a ratio of 100x up to 500 times. Both physical and chemical properties, including crystallographic structure, surface area, density, electronic properties, expansion behavior, chemical reactivity are affected by the intercalation agent and the quality of intercalation determine the initial expansion temperature and expansion ratio. A high grades expandable graphite has a high proportion of intercalation layers. The size and thickness of the flake graphite play a significant effect on the expansion ratio.
When expandable graphite used as a flame retardant, the heat expanded graphite layer turn in to “Char” and this retards the spread of fire. As expandable graphite with it characteristic of halogen free, heavy metals free, reduces fume formation, non-polluting, high heat resistance, radiation resistance and compression resilience thus make it an excellent choice as flame retardant in many fire protection products. Innographitech offers a wide variety of high-quality expandable graphite and the expertise to help our customer to optimize their specific application to their advantage.