Plastic PEEK

Plastic PEEK (bulk) strength, stiffness, density and thermal properties, with their source.

A bracket in Plastic PEEK, smooth finish.

Mechanical
Process	Bulk polymer (molded or machined)
Yield strength	98MPasourcetypical, tensile yield
Ultimate tensile strength	not sourced
Compressive strength	125MPasourcetypical, 23 C
Flexural strength	165MPasourcetypical, flexural stress at yield, 23 C
Elongation at break	25%sourcetypical, at break
Young's modulus (stiffness)	4GPasourcetypical (nominal)
Density	1,300kg/m³sourcetypical (crystalline)
Strength to weight	75.4kN·m/kg
Stiffness to weight	3.08MN·m/kg
Poisson's ratio	0.38sourcetypical
Shear modulus	1.45GPa
Bulk modulus	5.56GPa
Speed of sound	1,754m/s
Thermal
Thermal conductivity	0.29W/m·Ksourcetypical, average, 23 C
Thermal expansion	55µm/m·Ksourceaverage of flow/cross-flow, below Tg (<143 C)
100 mm part over a 50 °C swing	275µm growth
Specific heat	2,200J/kg·Ksourcetypical, 23 °C, DSC (Victrex PEEK 450G TDS, revision Jul 2012)
Heats up and cools (diffusivity)	0.101mm²/s
Thermal shock resistance	80.1W/m
Melting point	343°Csourcetypical, DSC
Glass transition	143°Csourceonset (midpoint 150 C)
Max service temperature	240°CsourceUL 746B RTI, mechanical strength (continuous use index)
Values for	Victrex PEEK 450G (unreinforced, injection moulded), Victrex TDS rev. March 2026; Poisson from Victrex fluid-management flyer (2020-07)

Among 59 materials

Stiffness against density

Strength against density