Materials / Compare
Glass vs. Plastic PTFE
Compare Glass vs. Plastic PTFE strength, stiffness, weight and thermal properties.
| Try it on a partA sample part to run stress or thermal on, free in your browser | Open in LessCAD | Open in LessCAD |
|---|---|---|
| Mechanical | ||
| Yield strength | not given (tensile used) | 9MPasourcetypical yield strength at 23 °C (Teflon PTFE, Table 8) |
| Ultimate tensile strength | 41MPasourcetypical mean surface tensile stress at fracture (MOR), 60 s load, weathered, 50% breakage probability | 39.3MPasourcetypical, skived tape 0.13 mm |
| Flexural strength | 41MPasourcemean MOR (same value as tensile) | not sourced |
| Elongation at break | not sourced | 350%sourcetypical, skived tape 0.13 mm |
| Young's modulus (stiffness) | 72GPasourcetypical | not sourced |
| Density | 2,500kg/m³sourcetypical | 2,160kg/m³sourcetypical (standard specific gravity, ASTM D4894) |
| Strength to weight | 16.4kN·m/kg3.94x higher | 4.17kN·m/kg |
| Stiffness to weight | 28.8MN·m/kg | not sourced |
| Poisson's ratio | 0.22sourcetypical | 0.46sourcetypical, 23 °C (Teflon PTFE resins, Chemours handbook) |
| Shear modulus | 29.5GPa | not sourced |
| Bulk modulus | 42.9GPa | not sourced |
| Speed of sound | 5,367m/s | not sourced |
| Thermal | ||
| Thermal conductivity | 0.937W/m·Ksourcetypical at 75 F | 0.25W/m·Ksourcetypical, granular resin, 4.6 mm specimen |
| Thermal expansion | 8.3µm/m·Ksourcetypical, 75-575 F | 100µm/m·Ksourcetypical, granular resin, 23-60 °C (ASTM E228) |
| 100 mm part over a 50 °C swing | 41.5µm growth12x less | 500µm growth |
| Specific heat | 880J/kg·Ksourcetypical at 75 F | 1,400J/kg·Ksourcetypical, granular resin, 20 °C (ASTM D4591) |
| Heats up and cools (diffusivity) | 0.426mm²/s5.15x faster | 0.0827mm²/s |
| Thermal shock resistance | 50.1W/m | not sourced |
| Melting point | not sourced | 327°Csourcesecond melting peak (sintered polymer), +/-10 |
| Max service temperature | 511°Csourcestrain point (ASTM C336) - stress-relaxation onset, not a rated service limit | 260°Csourceservice temperature (Chemours general Teflon PTFE statement) |
| Values for | Annealed soda-lime-silica float glass, Pilkington North America Technical Bulletin ATS-129 (04/2025) | Chemours Teflon PTFE 7C X granular molding resin, typical values (tensile/elongation measured on 0.13 mm skived tape) |
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 Glass stronger than Plastic PTFE?
Glass is stronger: its tensile strength is 41 MPa against yield strength 9 MPa for Plastic PTFE (4.56x).
Which is lighter, Glass or Plastic PTFE?
Plastic PTFE is lighter: 2,160 kg/m³ against 2,500 kg/m³ for Glass.
Which is lighter for the same job, Glass or Plastic PTFE?
For the same stiffness or strength: Glass is lighter for a strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Glass | Plastic PTFE |
|---|---|---|
| Strong rod or tie | lighter | 3.94x heavier |
| Strong beam | lighter | 2.37x heavier |
| Strong panel or plate | lighter | 1.84x 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, Glass or Plastic PTFE?
Glass conducts heat better: 0.937 W/m·K against 0.25 W/m·K for Plastic PTFE.
Which expands less with temperature?
Glass expands less: 8.3 µm/m·K against 100 µm/m·K for Plastic PTFE.