Thermal conductivity against densityHigher and further left: spreads more heat for its weightThermal expansion against thermal conductivityLower and further right: warps less when heated
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Technical Bulletin ATS-129: Properties of Soda-Lime Silica Float Glass (2025)Pilkington North Americaarchived copyGlass · Ultimate tensile strength: typical mean surface tensile stress at fracture (MOR), 60 s load, weathered, 50% breakage probabilityGlass · Flexural strength: mean MOR (same value as tensile)Glass · Young's modulus (stiffness): typicalGlass · Density: typicalGlass · Poisson's ratio: typicalGlass · Thermal conductivity: typical at 75 FGlass · Thermal expansion: typical, 75-575 FGlass · Specific heat: typical at 75 FGlass · Max service temperature: strain point (ASTM C336) - stress-relaxation onset, not a rated service limit
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Linatex Premium Rubber Spec Sheet (WMD0118, 2023)Weir MineralsRubber · Ultimate tensile strength: typicalRubber · Elongation at break: typicalRubber · Density: typical (specific gravity)Rubber · Max service temperature: continuous use operating range
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Compressibility of Natural Rubber at Pressures Below 500 kg/cm², J. Res. NBS 68A (1964)National Institute of Standards and Technologyarchived copyRubber · Poisson's ratio: government (NBS J. Res. 68A, 1964): computed by NBS for peroxide-cured gum NR vulcanizate, 25 °C, infinitesimal deformation (0.49 in the solver: the linear element locks as the ratio nears 0.5 (nearly incompressible).)Rubber · Specific heat: government (NBS J. Res. 68A, Table 7; values observed for unvulcanized NR by Bekkedahl and Matheson), 25 °C
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Thermal Conductivity of Soft Vulcanized Natural Rubber: Selected Values (AD 643325)Defense Technical Information Centerarchived copyRubber · Thermal conductivity: government selected value (US Army Natick Laboratories TR 66-49-PR, 1966), soft vulcanized natural rubber, 25 °C
Each number points to the document that states it, with the exact basis. Values without a number are computed from the sourced ones. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.
Questions
Mechanical
Is Glass stronger than Rubber?
Glass is stronger: its tensile strength is 41 MPa against 23 MPa for Rubber (1.78x).
Which is lighter, Glass or Rubber?
Rubber is lighter: 960 kg/m³ against 2,500 kg/m³ for Glass.
Which is lighter for the same job, Glass or Rubber?
For the same stiffness or strength: Rubber is lighter for a strong rod or tie, strong beam, strong panel or plate.
Part that must be
Glass
Rubber
Strong rod or tie
46% heavier
lighter
Strong beam
1.77x heavier
lighter
Strong panel or plate
1.95x heavier
lighter
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).
Thermal
Which handles higher temperatures, Glass or Rubber?
Glass does: 511 °C against 70 °C for Rubber.
Which conducts heat better, Glass or Rubber?
Glass conducts heat better: 0.937 W/m·K against 0.151 W/m·K for Rubber.