Plastic PMMA vs. Plastic Polycarbonate

Compare Plastic PMMA vs. Plastic Polycarbonate strength, stiffness, weight and thermal properties.

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Plastic PMMABulk polymer (molded or machined)

Plastic PolycarbonateBulk polymer (molded or machined)

Mechanical
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Yield strength	not given (tensile used)	65MPasourcetypical, tensile yield
Ultimate tensile strength	80MPasourcetypical, 23 °C	65MPasourcetypical, stress at break
Compressive strength	110MPasourcecompressive yield stress, typical	not sourced
Flexural strength	115MPasourcetypical	97MPasourcetypical, flexural strength
Elongation at break	5.5%sourcetypical	125%sourcetypical, strain at break
Young's modulus (stiffness)	3.3GPasourcetypical, short-term	2.4GPasourcetypical
Density	1,190kg/m³sourcetypical	1,200kg/m³sourcetypical
Strength to weight	67.2kN·m/kg24% higher	54.2kN·m/kg
Stiffness to weight	2.77MN·m/kg39% higher	2MN·m/kg
Poisson's ratio	0.37sourcetypical	0.38sourcetypical, polycarbonate family (Covestro Part and Mold Design guide, Table 3-1)
Shear modulus	1.2GPa39% stiffer in shear	0.87GPa
Bulk modulus	4.23GPa	3.33GPa
Speed of sound	1,665m/s	1,414m/s
Thermal
Thermal conductivity	0.19W/m·Ksourcetypical	0.2W/m·Ksourcetypical, through-plane, 23 C
Thermal expansion	70µm/m·Ksource0-50 °C	65µm/m·Ksourcetypical, 23-55 C, parallel and normal
100 mm part over a 50 °C swing	350µm growth	325µm growth8% less
Specific heat	1,470J/kg·Ksourcetypical	1,172J/kg·Ksourcetypical (guide value), Bayer ASTM datasheet for Makrolon 2405, ASTM D 2766
Heats up and cools (diffusivity)	0.109mm²/s	0.142mm²/s31% faster
Thermal shock resistance	41.5W/m	51.7W/m25% more resistant
Glass transition	not sourced	144°Csourcetypical, DSC 10 C/min
Max service temperature	80°Csourcemax. permanent service temperature	125°CsourceUL 746B RTI, tensile strength, 1.5 mm
Values for	Röhm PLEXIGLAS GS 0F00 cast acrylic sheet, typical values at 23 °C / 50 % RH (Röhm Technical Information Ref. No. 211-1)	Covestro Makrolon 2405 general-purpose PC (MVR 19), Covestro technical datasheet version 2026-09-28, typical values

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 Plastic PMMA stronger than Plastic Polycarbonate?

Plastic PMMA is stronger: its tensile strength is 80 MPa against yield strength 65 MPa for Plastic Polycarbonate (23%).

Which is lighter, Plastic PMMA or Plastic Polycarbonate?

Plastic PMMA is lighter: 1,190 kg/m³ against 1,200 kg/m³ for Plastic Polycarbonate.

Which is stiffer, Plastic PMMA or Plastic Polycarbonate?

Plastic PMMA is stiffer: Young's modulus 3.3 GPa against 2.4 GPa for Plastic Polycarbonate, so the same part in Plastic PMMA deflects less under the same load.

Which is lighter for the same job, Plastic PMMA or Plastic Polycarbonate?

For the same stiffness or strength: Plastic PMMA is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.

Part that must be	Plastic PMMA	Plastic Polycarbonate
Stiff rod or tie (tension)	lighter	39% heavier
Stiff beam (bending)	lighter	18% heavier
Stiff panel or plate	lighter	12% heavier
Strong rod or tie	lighter	24% heavier
Strong beam	lighter	16% heavier
Strong panel or plate	lighter	12% 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, Plastic PMMA or Plastic Polycarbonate?

Plastic Polycarbonate conducts heat better: 0.2 W/m·K against 0.19 W/m·K for Plastic PMMA.

Which expands less with temperature?

Plastic Polycarbonate expands less: 65 µm/m·K against 70 µm/m·K for Plastic PMMA.

Among 59 materials

Stiffness against density

Strength against density