PET có công thức là

[–NH–(CH₂)₂–CO–]ₙ.

[–O–CH₂–CH₂–O–CO–C₆H₄–CO–]ₙ.

[–CH₂–CH₂–COO–]ₙ.

[–O–CH₂–CH₂–CO–CH₂–CH₂–O–]ₙ.