Materials / Compare
Plastic POM/Acetal vs. Plastic Polypropylene
Compare Plastic POM/Acetal vs. Plastic Polypropylene 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 | 69MPasourcetypical (single ASTM D638 tensile strength) | 33MPasourcetypical, tensile stress at yield ISO 527 |
| Ultimate tensile strength | 69MPasourcetypical | not sourced |
| Compressive strength | 124MPasourcecompressive stress at 10% deformation | not sourced |
| Flexural strength | 99MPasourceflexural yield strength, typical | not sourced |
| Elongation at break | 75%sourcetypical | not sourced |
| Young's modulus (stiffness) | 2.8GPasourcetypical | 1.45GPasourcetypical, tensile modulus ISO 527 |
| Density | 1,420kg/m³sourcetypical (DuPont product information for Delrin 100 NC010; 'The data listed here fall within the normal range of product properties') | 900kg/m³sourcetypical, 23 °C ISO 1183-1 |
| Strength to weight | 48.6kN·m/kg33% higher | 36.7kN·m/kg |
| Stiffness to weight | 1.97MN·m/kg22% higher | 1.61MN·m/kg |
| Poisson's ratio | 0.35sourcetypical | 0.42sourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene) |
| Shear modulus | 1.04GPa2.03x stiffer in shear | 0.511GPa |
| Bulk modulus | 3.11GPa | 3.02GPa |
| Speed of sound | 1,404m/s | 1,269m/s |
| Thermal | ||
| Thermal conductivity | 0.4W/m·Ksourcetypical | 0.17–0.22W/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene) |
| Thermal expansion | 122µm/m·Ksourcemean, 29 to 60 °C | 80–100µm/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene) |
| 100 mm part over a 50 °C swing | 610µm growth | 450µm growth36% less |
| Specific heat | 1,465J/kg·Ksourceaverage -18 to 100 °C, Delrin acetal resins (not grade-specific) | not sourced |
| Heats up and cools (diffusivity) | 0.192mm²/s | not sourced |
| Thermal shock resistance | 52.5W/m1.84x more resistant | 28.6W/m |
| Melting point | 175°Csourcecrystalline melting point | not sourced |
| Max service temperature | 125°CsourceHDT 1.8 MPa (annealed) | 90°CsourceHDT 0.45 MPa (ISO 75B), unannealed |
| Values for | DuPont Delrin 100 acetal homopolymer, Table 2 'Typical Properties of Delrin Acetal Resins' (ASTM methods), Delrin Design Guide Module III hosted on delrin.com | LyondellBasell Moplen HP501H polypropylene homopolymer (general purpose), typical ISO values |
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 POM/Acetal stronger than Plastic Polypropylene?
Plastic POM/Acetal is stronger: its yield strength is 69 MPa against 33 MPa for Plastic Polypropylene (2.09x).
Which is lighter, Plastic POM/Acetal or Plastic Polypropylene?
Plastic Polypropylene is lighter: 900 kg/m³ against 1,420 kg/m³ for Plastic POM/Acetal.
Which is stiffer, Plastic POM/Acetal or Plastic Polypropylene?
Plastic POM/Acetal is stiffer: Young's modulus 2.8 GPa against 1.45 GPa for Plastic Polypropylene, so the same part in Plastic POM/Acetal deflects less under the same load.
Which is lighter for the same job, Plastic POM/Acetal or Plastic Polypropylene?
For the same stiffness or strength: Plastic POM/Acetal is lighter for a stiff rod or tie (tension), strong rod or tie, strong beam; Plastic Polypropylene is lighter for a stiff beam (bending), stiff panel or plate, strong panel or plate.
| Part that must be | Plastic POM/Acetal | Plastic Polypropylene |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 22% heavier |
| Stiff beam (bending) | 14% heavier | lighter |
| Stiff panel or plate | 27% heavier | lighter |
| Strong rod or tie | lighter | 33% heavier |
| Strong beam | lighter | 4% heavier |
| Strong panel or plate | 9% heavier | lighter |
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 POM/Acetal or Plastic Polypropylene?
Plastic POM/Acetal conducts heat better: 0.4 W/m·K against 0.195 W/m·K for Plastic Polypropylene.
Which expands less with temperature?
Plastic Polypropylene expands less: 90 µm/m·K against 122 µm/m·K for Plastic POM/Acetal.
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