How this works
The Fox equation estimates the glass transition temperature of a random copolymer or a miscible polymer blend from the weight fraction and homopolymer Tg of each component. It assumes the components mix freely at the segmental level with no specific interactions (hydrogen bonding, ionic association) and no leftover monomer or solvent acting as a plasticizer.
This works reasonably well for statistical copolymers and truly miscible blends. It does not apply to block copolymers or phase separated blends, which typically show two distinct glass transitions instead of one intermediate value, since each block or phase relaxes on its own.
Tg calculator
| Component | Normalized wt fraction | Tg (K) | wi ÷ Tg,i |
|---|
Reference homopolymer Tg values
Typical literature values for the atactic or common commercial form. Real Tg depends on tacticity, molecular weight, and measurement method (DSC heating rate, for example), so treat these as starting points.
| Polymer | Typical Tg (°C) |
|---|