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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Victrex PEEK 450G (unreinforced, injection moulded), Victrex TDS rev. March 2026; Poisson from Victrex fluid-management flyer (2020-07)
Plastic PMMA
Röhm PLEXIGLAS GS 0F00 cast acrylic sheet, typical values at 23 °C / 50 % RH (Röhm Technical Information Ref. No. 211-1)
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VICTREX PEEK 450G Technical Data SheetVictrexPlastic PEEK · Yield strength: typical, tensile yieldPlastic PEEK · Compressive strength: typical, 23 CPlastic PEEK · Flexural strength: typical, flexural stress at yield, 23 CPlastic PEEK · Elongation at break: typical, at breakPlastic PEEK · Young's modulus (stiffness): typical (nominal)Plastic PEEK · Density: typical (crystalline)Plastic PEEK · Thermal conductivity: typical, average, 23 CPlastic PEEK · Thermal expansion: average of flow/cross-flow, below Tg (<143 C)Plastic PEEK · Melting point: typical, DSCPlastic PEEK · Glass transition: onset (midpoint 150 C)Plastic PEEK · Max service temperature: UL 746B RTI, mechanical strength (continuous use index)
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PLEXIGLAS GS and XT Technical Information (Ref. No. 211-1)Röhmarchived copyPlastic PMMA · Ultimate tensile strength: typical, 23 °CPlastic PMMA · Compressive strength: compressive yield stress, typicalPlastic PMMA · Flexural strength: typicalPlastic PMMA · Elongation at break: typicalPlastic PMMA · Young's modulus (stiffness): typical, short-termPlastic PMMA · Density: typicalPlastic PMMA · Poisson's ratio: typicalPlastic PMMA · Thermal conductivity: typicalPlastic PMMA · Thermal expansion: 0-50 °CPlastic PMMA · Specific heat: typicalPlastic PMMA · Max service temperature: max. permanent service temperature
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VICTREX PEEK for Use in Fluid Management (2020)VictrexPlastic PEEK · Poisson's ratio: typical
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VICTREX PEEK 450G Technical Data Sheet (2012)Victrexarchived copyPlastic PEEK · Specific heat: typical, 23 °C, DSC (Victrex PEEK 450G TDS, revision Jul 2012)
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 PEEK stronger than Plastic PMMA?
Plastic PEEK is stronger: its yield strength is 98 MPa against tensile strength 80 MPa for Plastic PMMA (23%).
Which is lighter, Plastic PEEK or Plastic PMMA?
Plastic PMMA is lighter: 1,190 kg/m³ against 1,300 kg/m³ for Plastic PEEK.
Which is stiffer, Plastic PEEK or Plastic PMMA?
Plastic PEEK is stiffer: Young's modulus 4 GPa against 3.3 GPa for Plastic PMMA, so the same part in Plastic PEEK deflects less under the same load.
Which is lighter for the same job, Plastic PEEK or Plastic PMMA?
For the same stiffness or strength: Plastic PEEK is lighter for a stiff rod or tie (tension), strong rod or tie, strong beam, strong panel or plate; Plastic PMMA is lighter for a stiff panel or plate.
Part that must be
Plastic PEEK
Plastic PMMA
Stiff rod or tie (tension)
lighter
11% heavier
Stiff beam (bending)
about equal
about equal
Stiff panel or plate
2% heavier
lighter
Strong rod or tie
lighter
12% heavier
Strong beam
lighter
5% heavier
Strong panel or plate
lighter
1% 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 is more ductile, Plastic PEEK or Plastic PMMA?
Plastic PEEK stretches further before it breaks: 25% elongation at break against 5.5% for Plastic PMMA.
Thermal
Which handles higher temperatures, Plastic PEEK or Plastic PMMA?
Plastic PEEK does: 240 °C against 80 °C for Plastic PMMA.
Which conducts heat better, Plastic PEEK or Plastic PMMA?
Plastic PEEK conducts heat better: 0.29 W/m·K against 0.19 W/m·K for Plastic PMMA.
Which expands less with temperature?
Plastic PEEK expands less: 55 µm/m·K against 70 µm/m·K for Plastic PMMA.