Plastic PMMA vs. Rubber

Compare Plastic PMMA vs. Rubber strength, stiffness, weight and thermal properties.

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Plastic PMMABulk polymer (molded or machined)

RubberBulk polymer (molded or machined)

Mechanical
Try it on a partA bracket to run stress or thermal on, free in your browser	Open in LessCAD	Open in LessCAD
Yield strength	not given (tensile used)	not given (tensile used)
Ultimate tensile strength	80MPasourcetypical, 23 °C	23MPasourcetypical
Compressive strength	110MPasourcecompressive yield stress, typical	not sourced
Flexural strength	115MPasourcetypical	not sourced
Elongation at break	5.5%sourcetypical	830%sourcetypical151x more ductile
Young's modulus (stiffness)	3.3GPasourcetypical, short-term	not sourced
Density	1,190kg/m³sourcetypical	960kg/m³sourcetypical (specific gravity)
Strength to weight	67.2kN·m/kg2.81x higher	24kN·m/kg
Stiffness to weight	2.77MN·m/kg	not sourced
Poisson's ratio	0.37sourcetypical	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	1.2GPa	not sourced
Bulk modulus	4.23GPa	not sourced
Speed of sound	1,665m/s	not sourced
Thermal
Thermal conductivity	0.19W/m·Ksourcetypical	0.151W/m·Ksourcegovernment selected value (US Army Natick Laboratories TR 66-49-PR, 1966), soft vulcanized natural rubber, 25 °C
Thermal expansion	70µm/m·Ksource0-50 °C	not sourced
100 mm part over a 50 °C swing	350µm growth	not sourced
Specific heat	1,470J/kg·Ksourcetypical	1,881J/kg·Ksourcegovernment (NBS J. Res. 68A, Table 7; values observed for unvulcanized NR by Bekkedahl and Matheson), 25 °C
Heats up and cools (diffusivity)	0.109mm²/s30% faster	0.0836mm²/s
Thermal shock resistance	41.5W/m	not sourced
Max service temperature	80°Csourcemax. permanent service temperature	70°Csourcecontinuous use operating range
Values for	Röhm PLEXIGLAS GS 0F00 cast acrylic sheet, typical values at 23 °C / 50 % RH (Röhm Technical Information Ref. No. 211-1)	Weir Minerals Linatex Premium rubber (95 % natural rubber), typical physical properties, spec sheet WMD0118/202305

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 Rubber?

Plastic PMMA is stronger: its tensile strength is 80 MPa against 23 MPa for Rubber (3.48x).

Which is lighter, Plastic PMMA or Rubber?

Rubber is lighter: 960 kg/m³ against 1,190 kg/m³ for Plastic PMMA.

Which is lighter for the same job, Plastic PMMA or Rubber?

For the same stiffness or strength: Plastic PMMA is lighter for a strong rod or tie, strong beam, strong panel or plate.

Part that must be	Plastic PMMA	Rubber
Strong rod or tie	lighter	2.81x heavier
Strong beam	lighter	1.85x heavier
Strong panel or plate	lighter	1.5x 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 Rubber?

Rubber stretches further before it breaks: 830% elongation at break against 5.5% for Plastic PMMA.

Which conducts heat better, Plastic PMMA or Rubber?

Plastic PMMA conducts heat better: 0.19 W/m·K against 0.151 W/m·K for Rubber.

Among 59 materials

Stiffness against density

Strength against density