Plastic PTFE vs. Rubber

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

Plastic PTFEBulk polymer (molded or machined)

RubberBulk polymer (molded or machined)

Mechanical	Plastic PTFE	Rubber
Yield strength	9MPa1	not given (tensile used)
Ultimate tensile strength	39.3MPa21.71x stronger	23MPa3
Elongation at break	350%2	830%32.37x more ductile
Young's modulus (stiffness)	not sourced	not sourced
Density	2,160kg/m³2	960kg/m³32.25x lighter
Strength to weight	4.17kN·m/kg	24kN·m/kg5.75x higher
Stiffness to weight	not sourced	not sourced
Poisson's ratio	0.461	government0.54
Shear modulus	not sourced	not sourced
Bulk modulus	not sourced	not sourced
Speed of sound	not sourced	not sourced

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal	Plastic PTFE	Rubber
Thermal conductivity	0.25W/m·K11.66x more heat through a fin	0.151W/m·K5
Thermal expansion	100µm/m·K1	not sourced
100 mm part over a 50 °C swing	500µm growth	not sourced
Specific heat	1,400J/kg·K1	government1,881J/kg·K434% higher
Heats up and cools (diffusivity)	0.0827mm²/s	0.0836mm²/s1% faster
Thermal shock resistance	not sourced	not sourced
Melting point	second melting peak327°C2	not sourced
Max service temperature	service temperature260°C6190 °C hotter	70°C3

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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Sources6 documents: Chemours, Weir Minerals, National Institute of Standards and Technology, Defense Technical Information Center

Plastic PTFE: Chemours Teflon PTFE 7C X granular molding resin, typical values (tensile/elongation measured on 0.13 mm skived tape)
Rubber: Weir Minerals Linatex Premium rubber (95 % natural rubber), typical physical properties, spec sheet WMD0118/202305

1
Teflon PTFE Fluoropolymer Resin Properties HandbookChemoursarchived copyPlastic PTFE · Yield strength: typical yield strength at 23 °C (Teflon PTFE, Table 8)Plastic PTFE · Poisson's ratio: typical, 23 °C (Teflon PTFE resins, Chemours handbook)Plastic PTFE · Thermal conductivity: typical, granular resin, 4.6 mm specimenPlastic PTFE · Thermal expansion: typical, granular resin, 23-60 °C (ASTM E228)Plastic PTFE · Specific heat: typical, granular resin, 20 °C (ASTM D4591)
2
Teflon PTFE 7C X Product InformationChemoursarchived copyPlastic PTFE · Ultimate tensile strength: typical, skived tape 0.13 mmPlastic PTFE · Elongation at break: typical, skived tape 0.13 mmPlastic PTFE · Density: typical (standard specific gravity, ASTM D4894)Plastic PTFE · Melting point: second melting peak (sintered polymer), +/-10
3
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
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
6
Teflon PTFE 6C X Product InformationChemoursarchived copyPlastic PTFE · Max service temperature: service temperature (Chemours general Teflon PTFE statement)

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 PTFE stronger than Rubber?

Rubber is stronger: its tensile strength is 23 MPa against yield strength 9 MPa for Plastic PTFE (2.56x).

Which is lighter, Plastic PTFE or Rubber?

Rubber is lighter: 960 kg/m³ against 2,160 kg/m³ for Plastic PTFE.

Which is lighter for the same job, Plastic PTFE 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	Plastic PTFE	Rubber
Strong rod or tie	5.75x heavier	lighter
Strong beam	4.21x heavier	lighter
Strong panel or plate	3.6x 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).

Which is more ductile, Plastic PTFE or Rubber?

Rubber stretches further before it breaks: 830% elongation at break against 350% for Plastic PTFE.

Plastic PTFE vs. Rubber

Questions

Mechanical

Is Plastic PTFE stronger than Rubber?

Which is lighter, Plastic PTFE or Rubber?

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

Which is more ductile, Plastic PTFE or Rubber?

Thermal

Which handles higher temperatures, Plastic PTFE or Rubber?

Which conducts heat better, Plastic PTFE or Rubber?

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