Polyetherimide (PEI) is an amorphous, amber-to-transparent

thermoplastic A thermoplastic, or thermosoft plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains associate ...

with characteristics similar to the related plastic

PEEK Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family, used in engineering applications. The polymer was first developed in November 1978, later being introduced to the market by Vic ...

. When comparing PEI to PEEK, the former is cheaper but has lower impact strength and a tighter temperature range. Due to its

adhesive Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advant ...

properties and chemical stability it became a popular bed material for FFF 3D printers.

Structure

The molecular formula of the PEI monomer is and the

molecular weight A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...

is 592.61 g/mol. It contains

phthalimide Phthalimide is the organic compound with the formula C6H4(CO)2NH. It is the imide derivative of phthalic anhydride. It is a sublimable white solid that is slightly soluble in water but more so upon addition of base. It is used as a precursor ...

and bisphenol A sub-units.

Properties

The

glass transition temperature The glass–liquid transition, or glass transition, is the gradual and reversible transition in amorphous materials (or in amorphous regions within semicrystalline materials) from a hard and relatively brittle "glassy" state into a viscous or rub ...

of PEI is 217 °C (422 °F). Its amorphous

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...

at 25 °C is 1.27 g/cm³(.046 lb/in³). It is prone to stress cracking in

chlorinated solvent An organochloride, organochlorine compound, chlorocarbon, or chlorinated hydrocarbon is an organic compound containing at least one covalently bonded atom of chlorine. The chloroalkane class ( alkanes with one or more hydrogens substituted by chlo ...

s. Polyetherimide is able to resist high temperatures while maintaining stable electrical properties over a wide range of frequencies. This high strength material offers excellent chemical resistance and ductile properties suitable for various applications, even those involving steam exposure.

References

{{reflist Plastics Thermoplastics