Materials / Compare
Plastic PEEK vs. Plastic POM/Acetal
Compare Plastic PEEK vs. Plastic POM/Acetal strength, stiffness, weight and thermal properties.
| Try it on a partA bracket to run stress or thermal on, free in your browser | Open in LessCAD | Open in LessCAD |
|---|---|---|
| Mechanical | ||
| Yield strength | 98MPasourcetypical, tensile yield | 69MPasourcetypical (single ASTM D638 tensile strength) |
| Ultimate tensile strength | not sourced | 69MPasourcetypical |
| Compressive strength | 125MPasourcetypical, 23 C | 124MPasourcecompressive stress at 10% deformation |
| Flexural strength | 165MPasourcetypical, flexural stress at yield, 23 C | 99MPasourceflexural yield strength, typical |
| Elongation at break | 25%sourcetypical, at break | 75%sourcetypical |
| Young's modulus (stiffness) | 4GPasourcetypical (nominal) | 2.8GPasourcetypical |
| Density | 1,300kg/m³sourcetypical (crystalline) | 1,420kg/m³sourcetypical (DuPont product information for Delrin 100 NC010; 'The data listed here fall within the normal range of product properties') |
| Strength to weight | 75.4kN·m/kg1.55x higher | 48.6kN·m/kg |
| Stiffness to weight | 3.08MN·m/kg1.56x higher | 1.97MN·m/kg |
| Poisson's ratio | 0.38sourcetypical | 0.35sourcetypical |
| Shear modulus | 1.45GPa40% stiffer in shear | 1.04GPa |
| Bulk modulus | 5.56GPa | 3.11GPa |
| Speed of sound | 1,754m/s | 1,404m/s |
| Thermal | ||
| Thermal conductivity | 0.29W/m·Ksourcetypical, average, 23 C | 0.4W/m·Ksourcetypical |
| Thermal expansion | 55µm/m·Ksourceaverage of flow/cross-flow, below Tg (<143 C) | 122µm/m·Ksourcemean, 29 to 60 °C |
| 100 mm part over a 50 °C swing | 275µm growth2.22x less | 610µm growth |
| Specific heat | 2,200J/kg·Ksourcetypical, 23 °C, DSC (Victrex PEEK 450G TDS, revision Jul 2012) | 1,465J/kg·Ksourceaverage -18 to 100 °C, Delrin acetal resins (not grade-specific) |
| Heats up and cools (diffusivity) | 0.101mm²/s | 0.192mm²/s1.9x faster |
| Thermal shock resistance | 80.1W/m1.53x more resistant | 52.5W/m |
| Melting point | 343°Csourcetypical, DSC | 175°Csourcecrystalline melting point |
| Glass transition | 143°Csourceonset (midpoint 150 C) | not sourced |
| Max service temperature | 240°CsourceUL 746B RTI, mechanical strength (continuous use index) | 125°CsourceHDT 1.8 MPa (annealed) |
| Values for | Victrex PEEK 450G (unreinforced, injection moulded), Victrex TDS rev. March 2026; Poisson from Victrex fluid-management flyer (2020-07) | DuPont Delrin 100 acetal homopolymer, Table 2 'Typical Properties of Delrin Acetal Resins' (ASTM methods), Delrin Design Guide Module III hosted on delrin.com |
Every value links to the document that states it. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.
Questions
Is Plastic PEEK stronger than Plastic POM/Acetal?
Plastic PEEK is stronger: its yield strength is 98 MPa against 69 MPa for Plastic POM/Acetal (42%).
Which is lighter, Plastic PEEK or Plastic POM/Acetal?
Plastic PEEK is lighter: 1,300 kg/m³ against 1,420 kg/m³ for Plastic POM/Acetal.
Which is stiffer, Plastic PEEK or Plastic POM/Acetal?
Plastic PEEK is stiffer: Young's modulus 4 GPa against 2.8 GPa for Plastic POM/Acetal, so the same part in Plastic PEEK deflects less under the same load.
Which is lighter for the same job, Plastic PEEK or Plastic POM/Acetal?
For the same stiffness or strength: Plastic PEEK is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Plastic PEEK | Plastic POM/Acetal |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 1.56x heavier |
| Stiff beam (bending) | lighter | 31% heavier |
| Stiff panel or plate | lighter | 23% heavier |
| Strong rod or tie | lighter | 1.55x heavier |
| Strong beam | lighter | 38% heavier |
| Strong panel or plate | lighter | 30% heavier |
For the same stiffness or strength, mass scales with density over stiffness (or strength) raised to a power set by how the part is loaded: 1 for a rod in tension, 1/2 for a beam in bending, 1/3 for a panel (the standard material-selection indices).
Which conducts heat better, Plastic PEEK or Plastic POM/Acetal?
Plastic POM/Acetal conducts heat better: 0.4 W/m·K against 0.29 W/m·K for Plastic PEEK.
Which expands less with temperature?
Plastic PEEK expands less: 55 µm/m·K against 122 µm/m·K for Plastic POM/Acetal.