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CAS number 61128-46-9 YesY
Molecular formula (C37H24O6N2)n
Molar mass Variable
Appearance Amber-to-transparent solid
Density 1.27 g/cm3
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Polyetherimide (PEI) is an amorphous, amber-to-transparent thermoplastic with characteristics similar to the related plastic PEEK. Relative to PEEK, PEI is cheaper, but is lower in impact strength and usable temperature.[1]


The molecular formula of the repeating unit of PEI is C37H24O6N2 and the molecular weight is 592 g/mol.


The glass transition temperature of PEI is 216 °C. Its amorphous density at 25 °C is 1.27 g/cm3. It is prone to stress cracking in chlorinated solvents.


Ultem is a family of PEI products manufactured by SABIC as a result of acquiring the General Electric Plastics Division in 2007. Ultem resins are used in medical and chemical instrumentation due to their heat resistance, solvent resistance and flame resistance. Ultem 1000 (standard, unfilled polyetherimide) has a high dielectric strength, natural flame resistance, and extremely low smoke generation. Ultem has high mechanical properties and performs in continuous use to 340 °F (170 °C). Ultem 1000 has typical thermal conductivity of 0.22 W/(m·K) (but some sources give 0.122 W/(m.K)).


  1. ^ http://www.mcmaster.com/#ultem/=otzvqt Referenced Oct 7, 2013