Materials / Compare
Plastic PMMA vs. Plastic POM/Acetal
Compare Plastic PMMA 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 | not given (tensile used) | 69MPasourcetypical (single ASTM D638 tensile strength) |
| Ultimate tensile strength | 80MPasourcetypical, 23 °C | 69MPasourcetypical |
| Compressive strength | 110MPasourcecompressive yield stress, typical | 124MPasourcecompressive stress at 10% deformation |
| Flexural strength | 115MPasourcetypical | 99MPasourceflexural yield strength, typical |
| Elongation at break | 5.5%sourcetypical | 75%sourcetypical13.6x more ductile |
| Young's modulus (stiffness) | 3.3GPasourcetypical, short-term | 2.8GPasourcetypical |
| Density | 1,190kg/m³sourcetypical | 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 | 67.2kN·m/kg38% higher | 48.6kN·m/kg |
| Stiffness to weight | 2.77MN·m/kg41% higher | 1.97MN·m/kg |
| Poisson's ratio | 0.37sourcetypical | 0.35sourcetypical |
| Shear modulus | 1.2GPa16% stiffer in shear | 1.04GPa |
| Bulk modulus | 4.23GPa | 3.11GPa |
| Speed of sound | 1,665m/s | 1,404m/s |
| Thermal | ||
| Thermal conductivity | 0.19W/m·Ksourcetypical | 0.4W/m·Ksourcetypical2.11x more heat through a fin |
| Thermal expansion | 70µm/m·Ksource0-50 °C | 122µm/m·Ksourcemean, 29 to 60 °C |
| 100 mm part over a 50 °C swing | 350µm growth1.74x less | 610µm growth |
| Specific heat | 1,470J/kg·Ksourcetypical | 1,465J/kg·Ksourceaverage -18 to 100 °C, Delrin acetal resins (not grade-specific) |
| Heats up and cools (diffusivity) | 0.109mm²/s | 0.192mm²/s1.77x faster |
| Thermal shock resistance | 41.5W/m | 52.5W/m27% more resistant |
| Melting point | not sourced | 175°Csourcecrystalline melting point |
| Max service temperature | 80°Csourcemax. permanent service temperature | 125°CsourceHDT 1.8 MPa (annealed) |
| Values for | Röhm PLEXIGLAS GS 0F00 cast acrylic sheet, typical values at 23 °C / 50 % RH (Röhm Technical Information Ref. No. 211-1) | 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 PMMA stronger than Plastic POM/Acetal?
Plastic PMMA is stronger: its tensile strength is 80 MPa against yield strength 69 MPa for Plastic POM/Acetal (16%).
Which is lighter, Plastic PMMA or Plastic POM/Acetal?
Plastic PMMA is lighter: 1,190 kg/m³ against 1,420 kg/m³ for Plastic POM/Acetal.
Which is stiffer, Plastic PMMA or Plastic POM/Acetal?
Plastic PMMA is stiffer: Young's modulus 3.3 GPa against 2.8 GPa for Plastic POM/Acetal, so the same part in Plastic PMMA deflects less under the same load.
Which is lighter for the same job, Plastic PMMA or Plastic POM/Acetal?
For the same stiffness or strength: Plastic PMMA 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 PMMA | Plastic POM/Acetal |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 41% heavier |
| Stiff beam (bending) | lighter | 30% heavier |
| Stiff panel or plate | lighter | 26% heavier |
| Strong rod or tie | lighter | 38% heavier |
| Strong beam | lighter | 32% heavier |
| Strong panel or plate | lighter | 28% 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 is more ductile, Plastic PMMA or Plastic POM/Acetal?
Plastic POM/Acetal stretches further before it breaks: 75% elongation at break against 5.5% for Plastic PMMA.
Which conducts heat better, Plastic PMMA or Plastic POM/Acetal?
Plastic POM/Acetal conducts heat better: 0.4 W/m·K against 0.19 W/m·K for Plastic PMMA.
Which expands less with temperature?
Plastic PMMA expands less: 70 µm/m·K against 122 µm/m·K for Plastic POM/Acetal.