Material Identity
- Chemical name: Expanded graphite
- Base composition: Carbon (C)
- CAS number: 7782-42-5 (graphite, base material)
- Physical form: expandable or expanded particulate, flake, or worm-like structure
- What it is not: not a polymer, not a chemical intumescent, not a nanoscale graphene material
Activation & Trigger Conditions
- Trigger: thermal energy exposure
- Energy domain: heat-driven physical expansion and exfoliation
- Absent trigger: no expansion or barrier formation at low temperatures
- Insufficient condition: partial heating leads to incomplete expansion and weak barrier effect
- Excess condition: excessive heat can collapse structure or oxidize carbon in air
Functional Role
- Forms an expanded physical barrier under heat
- Provides electrically conductive pathways through carbon networks
- Reduces heat and mass transfer by volume expansion
- Contributes to char stability through structural reinforcement
Application Windows
- Compatible systems: polymers, elastomers, coatings, sealing materials, molded solids
- Loading range: formulation-dependent; no universal loading applies
- Processing notes: particle integrity and dispersion affect expansion efficiency and conductivity
Limitations & Failure Modes
- Poor dispersion → uneven expansion → localized barrier failure
- Low activation temperature mismatch → delayed expansion → reduced protective effect
- Oxidative environment at high temperature → carbon degradation → loss of structure
Alternatives & Trade-offs
- Chemical intumescents: rely on chemical reactions rather than physical expansion
- Carbon black: provides conductivity without volumetric expansion
- Graphene-based materials: offer high conductivity but lack macroscopic expansion behavior
When to Use
- When heat-triggered physical expansion is required
- When a conductive, carbon-based solid additive is acceptable
- When barrier formation relies on volume growth rather than chemistry
- When processing allows retention of particle structure
FAQ
Is expanded graphite chemically reactive in formulations?
No. Its primary function is physical expansion and carbon network formation rather than chemical reaction.
Does expanded graphite behave like graphene?
No. Expanded graphite is a bulk, layered material and does not exhibit nanoscale graphene behavior.
Why does performance vary between grades?
Expansion ratio, particle size, and residual intercalants vary by grade and processing route.
Data
No generic numerical values are listed. Expansion ratio, particle size, conductivity, and ash content are grade-specific and should be taken from supplier COA or test data.
Sources
General literature on expandable graphite and supplier technical documentation where available.