Plastic HDPE vs. Rubber

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

Plastic HDPEBulk polymer (molded or machined)

RubberBulk polymer (molded or machined)

Mechanical	Plastic HDPE	Rubber
Yield strength	24MPa1	not given (tensile used)
Ultimate tensile strength	not stated (yield given)	23MPa2
Elongation at break	not sourced	830%2
Young's modulus (stiffness)	0.9GPa1	not sourced
Density	950kg/m³1	960kg/m³2
Strength to weight	25.3kN·m/kg5% higher	24kN·m/kg
Stiffness to weight	0.947MN·m/kg	not sourced
Poisson's ratio	base material0.4–0.453	government0.54
Shear modulus	0.316GPa	not sourced
Bulk modulus	2GPa	not sourced
Speed of sound	973m/s	not sourced

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal	Plastic HDPE	Rubber
Thermal conductivity	base material0.4–0.49W/m·K3	0.151W/m·K5
Thermal expansion	base material120µm/m·K3	not sourced
100 mm part over a 50 °C swing	600µm growth	not sourced
Specific heat	base material2,250J/kg·K320% higher	government1,881J/kg·K4
Heats up and cools (diffusivity)	0.208mm²/s2.49x faster	0.0836mm²/s
Thermal shock resistance	56.9W/m	not sourced
Max service temperature	not sourced	70°C2

Thermal conductivity against densityHigher and further left: spreads more heat for its weight

Thermal expansion against thermal conductivityLower and further right: warps less when heated

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Sources5 documents: LyondellBasell, Weir Minerals, INEOS Olefins & Polymers USA, National Institute of Standards and Technology, Defense Technical Information Center

Plastic HDPE: LyondellBasell Hostalen 23050 B high density polyethylene, typical ISO values
Rubber: Weir Minerals Linatex Premium rubber (95 % natural rubber), typical physical properties, spec sheet WMD0118/202305

1
Hostalen 23050 B Product DataLyondellBasellPlastic HDPE · Yield strength: typical, tensile stress at yield 23 °C, 50 mm/min ISO 527Plastic HDPE · Young's modulus (stiffness): typical, tensile modulus 23 °C ISO 527Plastic HDPE · Density: typical, ISO 1183
2
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
3
Typical Engineering Properties of High Density PolyethyleneINEOS Olefins & Polymers USAarchived copyPlastic HDPE · Poisson's ratio: base material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE)Plastic HDPE · Thermal conductivity: base material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE)Plastic HDPE · Thermal expansion: base material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE)Plastic HDPE · Specific heat: base material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE)
4
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
5
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 Plastic HDPE stronger than Rubber?

Plastic HDPE is stronger: its yield strength is 24 MPa against tensile strength 23 MPa for Rubber (4%).

Which is lighter, Plastic HDPE or Rubber?

Plastic HDPE is lighter: 950 kg/m³ against 960 kg/m³ for Rubber.

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

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

Part that must be	Plastic HDPE	Rubber
Strong rod or tie	lighter	5% heavier
Strong beam	lighter	4% heavier
Strong panel or plate	lighter	3% 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).

Thermal

Which conducts heat better, Plastic HDPE or Rubber?

Plastic HDPE conducts heat better: 0.445 W/m·K against 0.151 W/m·K for Rubber.