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