Materials / Compare
Plastic Polypropylene vs. Stainless 304
Compare Plastic Polypropylene vs. Stainless 304 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 | 241MPasourcetypical, annealed, 70 °F (21 °C) |
| Ultimate tensile strength | not sourced | 586MPasourcetypical, annealed, 70 °F (21 °C) |
| Elongation at break | not sourced | 55%sourcetypical, annealed, in 2 in. (50.8 mm) |
| Young's modulus (stiffness) | 1.45GPasourcetypical, tensile modulus ISO 527 | 193GPasourcetypical, in tension |
| Density | 900kg/m³sourcetypical, 23 °C ISO 1183-1 | 8,030kg/m³sourcetypical |
| Strength to weight | 36.7kN·m/kg22% higher | 30kN·m/kg |
| Stiffness to weight | 1.61MN·m/kg | 24MN·m/kg14.9x higher |
| Poisson's ratio | 0.42sourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene) | 0.3sourcedesign value (structural stainless steels) |
| Shear modulus | 0.511GPa | 74.2GPa145x stiffer in shear |
| Bulk modulus | 3.02GPa | 161GPa |
| Speed of sound | 1,269m/s | 4,903m/s |
| Thermal | ||
| Thermal conductivity | 0.17–0.22W/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene) | 16.2W/m·Ksourceat 100 °C |
| Thermal expansion | 80–100µm/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene) | 16.9µm/m·Ksourcemean, 0–100 °C |
| 100 mm part over a 50 °C swing | 450µm growth | 84.5µm growth5.33x less |
| Specific heat | not sourced | 500J/kg·Ksourcemean, 0–100 °C |
| Heats up and cools (diffusivity) | not sourced | 4.03mm²/s |
| Thermal shock resistance | 28.6W/m | 838W/m29.3x more resistant |
| Melting point | not sourced | 1,399–1,454°Csourcemelting range |
| Max service temperature | 90°CsourceHDT 0.45 MPa (ISO 75B), unannealed | 899°Csourcecontinuous, oxidation (scaling) limit in air |
| Values for | LyondellBasell Moplen HP501H polypropylene homopolymer (general purpose), typical ISO values | Type 304, annealed flat-rolled (Cleveland-Cliffs 304/304L Product Data Bulletin, May 2021); Poisson's ratio from the Nickel Institute/SCI structural stainless design manual |
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 Stainless 304?
Stainless 304 is stronger: its yield strength is 241 MPa against 33 MPa for Plastic Polypropylene (7.3x).
Which is lighter, Plastic Polypropylene or Stainless 304?
Plastic Polypropylene is lighter: 900 kg/m³ against 8,030 kg/m³ for Stainless 304.
Which is stiffer, Plastic Polypropylene or Stainless 304?
Stainless 304 is stiffer: Young's modulus 193 GPa against 1.45 GPa for Plastic Polypropylene, so the same part in Stainless 304 deflects less under the same load.
Which is lighter for the same job, Plastic Polypropylene or Stainless 304?
For the same stiffness or strength: Plastic Polypropylene is lighter for a stiff panel or plate, strong rod or tie, strong beam, strong panel or plate; Stainless 304 is lighter for a stiff rod or tie (tension), stiff beam (bending).
| Part that must be | Plastic Polypropylene | Stainless 304 |
|---|---|---|
| Stiff rod or tie (tension) | 14.9x heavier | lighter |
| Stiff beam (bending) | 29% heavier | lighter |
| Stiff panel or plate | lighter | 1.75x heavier |
| Strong rod or tie | lighter | 22% heavier |
| Strong beam | lighter | 2.37x heavier |
| Strong panel or plate | lighter | 3.3x 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 Stainless 304?
Stainless 304 conducts heat better: 16.2 W/m·K against 0.195 W/m·K for Plastic Polypropylene.
Which expands less with temperature?
Stainless 304 expands less: 16.9 µm/m·K against 90 µm/m·K for Plastic Polypropylene.