0.42sourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene)
0.5sourcegovernment (NBS J. Res. 68A, 1964): computed by NBS for peroxide-cured gum NR vulcanizate, 25 °C, infinitesimal deformation0.49 in the solver: the linear element locks as the ratio nears 0.5 (nearly incompressible).
Shear modulus
0.511GPa
not sourced
Bulk modulus
3.02GPa
not sourced
Speed of sound
1,269m/s
not sourced
Thermal
Thermal conductivity
0.17–0.22W/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene)
0.151W/m·Ksourcegovernment selected value (US Army Natick Laboratories TR 66-49-PR, 1966), soft vulcanized natural rubber, 25 °C
Thermal expansion
80–100µm/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene)
not sourced
100 mm part over a 50 °C swing
450µm growth
not sourced
Specific heat
not sourced
1,881J/kg·Ksourcegovernment (NBS J. Res. 68A, Table 7; values observed for unvulcanized NR by Bekkedahl and Matheson), 25 °C
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 Rubber?
Plastic Polypropylene is stronger: its yield strength is 33 MPa against tensile strength 23 MPa for Rubber (43%).
Which is lighter, Plastic Polypropylene or Rubber?
Plastic Polypropylene is lighter: 900 kg/m³ against 960 kg/m³ for Rubber.
Which is lighter for the same job, Plastic Polypropylene or Rubber?
For the same stiffness or strength: Plastic Polypropylene is lighter for a strong rod or tie, strong beam, strong panel or plate.
Part that must be
Plastic Polypropylene
Rubber
Strong rod or tie
lighter
1.53x heavier
Strong beam
lighter
36% 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 conducts heat better, Plastic Polypropylene or Rubber?
Plastic Polypropylene conducts heat better: 0.195 W/m·K against 0.151 W/m·K for Rubber.