Materials / Compare

Rubber vs. Silicon

Compare Rubber vs. Silicon strength, stiffness, weight and thermal properties.

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RubberBulk polymer (molded or machined)
SiliconGrown single crystal
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Mechanical
Yield strengthnot given (tensile used)not given (tensile used)
Ultimate tensile strength23MPasourcetypical130MPasourcemodulus of rupture (bending fracture stress); brittle, no yield point
Flexural strengthnot sourced130MPasourcemodulus of rupture
Elongation at break830%sourcetypicalnot sourced
Young's modulus (stiffness)not sourced131GPasourcetypical (single quoted value of an anisotropic crystal)
Density960kg/m³sourcetypical (specific gravity)2,329kg/m³sourcetypical
Strength to weight24kN·m/kg55.8kN·m/kg2.33x higher
Stiffness to weightnot sourced56.2MN·m/kg
Poisson's ratio0.5sourcegovernment (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).0.221sourcetypical
Shear modulusnot sourced53.6GPa
Bulk modulusnot sourced78.3GPa
Speed of soundnot sourced7,500m/s
Thermal
Thermal conductivity0.151W/m·Ksourcegovernment selected value (US Army Natick Laboratories TR 66-49-PR, 1966), soft vulcanized natural rubber, 25 °C163W/m·Ksourcetypical at 313 K (40 °C)
Thermal expansionnot sourced2.62µm/m·Ksourcetypical at 300 K
100 mm part over a 50 °C swingnot sourced13.1µm growth
Specific heat1,881J/kg·Ksourcegovernment (NBS J. Res. 68A, Table 7; values observed for unvulcanized NR by Bekkedahl and Matheson), 25 °C732J/kg·Ksourcetypical
Heats up and cools (diffusivity)0.0836mm²/s95.6mm²/s1,143x faster
Thermal shock resistancenot sourced48,095W/m
Melting pointnot sourced1,412°Csourcetypical
Max service temperature70°Csourcecontinuous use operating range300°Csourceproducer's maximum application temperature (optical components)
Values forWeir Minerals Linatex Premium rubber (95 % natural rubber), typical physical properties, spec sheet WMD0118/202305Synthetic single-crystal silicon (cubic, diamond structure), Korth Kristalle (crystal grower) material data; Korth usually supplies Floating Zone (FZ) material, Czochralski (Cz) also offered. Silicon is elastically anisotropic; the producer quotes one modulus and the solver is isotropic.

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 Rubber stronger than Silicon?

Silicon is stronger: its tensile strength is 130 MPa against 23 MPa for Rubber (5.65x).

Which is lighter, Rubber or Silicon?

Rubber is lighter: 960 kg/m³ against 2,329 kg/m³ for Silicon.

Which is lighter for the same job, Rubber or Silicon?

For the same stiffness or strength: Rubber is lighter for a strong panel or plate; Silicon is lighter for a strong rod or tie, strong beam.

Part that must beRubberSilicon
Strong rod or tie2.33x heavierlighter
Strong beam31% heavierlighter
Strong panel or platelighter2% 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, Rubber or Silicon?

Silicon conducts heat better: 163 W/m·K against 0.151 W/m·K for Rubber.

Among 72 materials

1k10k0.1110100Density (kg/m³)Young's modulus (GPa)Plastic PLAPlastic PETGPlastic ABSPlastic TPUPlastic NylonAluminumSteelIronTitaniumSteel AISI 1018Stainless Steel 304Stainless Steel 316Aluminum 6061-T6Aluminum 7075-T6Brass C360Copper C110GlassSteel AISI 1045Steel AISI 4340Steel A992Stainless Steel 303Stainless Steel 17-4PHAluminum 2024-T351Aluminum 5052-H32Aluminum 7050-T7451Titanium Ti-6Al-4VBrass C260Nickel Inconel 718Magnesium AZ31B-H24Zinc Zamak 3Plastic ABS (bulk/injection)Plastic PolycarbonatePlastic POM/AcetalPlastic Nylon PA6Plastic Nylon PA66Plastic PEEKPlastic UHMWPEPlastic HDPEPlastic PolypropylenePlastic PMMAFDM ASAFDM PolycarbonateFDM PAHT-CFFDM HIPSSLA Resin Tough 2000SLS PA12 NylonDMLS AlSi10Mg AluminumDMLS Ti-6Al-4V ELI TitaniumDMLS 316L Stainless SteelDMLS 17-4PH Stainless SteelPCB Laminate FR-4Ceramic Alumina 96%Ceramic Aluminum NitrideAluminum A380Aluminum 6063-T6Aluminum 1100-OAluminum ADC12Magnesium AZ91DSolder SAC305Plastic PBT GF30Plastic PPS GF40Plastic LCP GF30Silicon
Stiffness against density
1k10k101001kDensity (kg/m³)Yield strength (MPa)Plastic PLAPlastic PETGPlastic ABSPlastic TPUPlastic NylonAluminumSteelIronTitaniumSteel AISI 1018Stainless Steel 304Stainless Steel 316Aluminum 6061-T6Aluminum 7075-T6Brass C360Copper C110GlassSteel AISI 1045Steel AISI 4340Steel A992Stainless Steel 303Stainless Steel 17-4PHAluminum 2024-T351Aluminum 5052-H32Aluminum 7050-T7451Titanium Ti-6Al-4VBrass C260Nickel Inconel 718Magnesium AZ31B-H24Zinc Zamak 3Plastic ABS (bulk/injection)Plastic PolycarbonatePlastic POM/AcetalPlastic Nylon PA6Plastic Nylon PA66Plastic PEEKPlastic PTFEPlastic UHMWPEPlastic HDPEPlastic PolypropylenePlastic PMMAFDM ASAFDM PolycarbonateFDM PAHT-CFFDM HIPSSLA Resin Tough 2000SLA Resin Elastic 50ASLS PA12 NylonDMLS AlSi10Mg AluminumDMLS Ti-6Al-4V ELI TitaniumDMLS 316L Stainless SteelDMLS 17-4PH Stainless SteelBrickPCB Laminate FR-4Ceramic Alumina 96%Aluminum A380Aluminum 6063-T6Aluminum 1100-OAluminum ADC12Magnesium AZ91DSolder SAC305Plastic PBT GF30Plastic PPS GF40Plastic LCP GF30RubberSilicon
Strength against density

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