Thermogravimetric Analysis (TGA) of Polyester
topic
TGA of PET: single-step degradation in N₂ at 400–450°C (Td onset ~380°C); 90% mass loss by 470°C; char residue <5% (cf. cellulose ~15% char). In air: second oxidation step at 500–600°C burns char. Activation energy for thermal degradation by Kissinger and Flynn–Wall–Ozawa methods: Ea ~200–230 kJ/mol. TGA-FTIR coupling identifies evolved gases (CO₂, CO, acetaldehyde, terephthalic acid fragments). Used to distinguish PET from PLA, PBT, other polyesters, and to assess thermal stability of FR additives.
Role
TGA provides definitive thermal stability characterisation and polymer identification. TGA–FTIR coupling for evolved gas analysis is particularly powerful for understanding thermal degradation mechanisms in fire-resistant and recycled polyester formulations.