Plastic PMMA vs. Plastic Polycarbonate

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

Plastic PMMABulk polymer (molded or machined)

Plastic PolycarbonateBulk polymer (molded or machined)

Mechanical	Plastic PMMA	Plastic Polycarbonate
Yield strength	not given (tensile used)	65MPa1
Ultimate tensile strength	80MPa2	65MPa1
Compressive strength	110MPa2	not sourced
Flexural strength	115MPa2	97MPa1
Elongation at break	5.5%2	125%122.7x more ductile
Young's modulus (stiffness)	3.3GPa238% stiffer	2.4GPa1
Density	1,190kg/m³2	1,200kg/m³1
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	0.372	0.383
Shear modulus	1.2GPa39% stiffer in shear	0.87GPa
Bulk modulus	4.23GPa27% higher	3.33GPa
Speed of sound	1,665m/s18% faster	1,414m/s

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal	Plastic PMMA	Plastic Polycarbonate
Thermal conductivity	0.19W/m·K2	0.2W/m·K1
Thermal expansion	0-50 °C70µm/m·K2	65µm/m·K1
100 mm part over a 50 °C swing	350µm growth	325µm growth8% less
Specific heat	1,470J/kg·K225% higher	1,172J/kg·K4
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°C1
Max service temperature	80°C2	UL 746B RTI125°C1

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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Sources4 documents: Covestro, Röhm, Bayer MaterialScience

Plastic PMMA: Röhm PLEXIGLAS GS 0F00 cast acrylic sheet, typical values at 23 °C / 50 % RH (Röhm Technical Information Ref. No. 211-1)
Plastic Polycarbonate: Covestro Makrolon 2405 general-purpose PC (MVR 19), Covestro technical datasheet version 2026-09-28, typical values

1
Makrolon 2405 Technical Data SheetCovestroPlastic Polycarbonate · Yield strength: typical, tensile yieldPlastic Polycarbonate · Ultimate tensile strength: typical, stress at breakPlastic Polycarbonate · Flexural strength: typical, flexural strengthPlastic Polycarbonate · Elongation at break: typical, strain at breakPlastic Polycarbonate · Young's modulus (stiffness): typicalPlastic Polycarbonate · Density: typicalPlastic Polycarbonate · Thermal conductivity: typical, through-plane, 23 CPlastic Polycarbonate · Thermal expansion: typical, 23-55 C, parallel and normalPlastic Polycarbonate · Glass transition: typical, DSC 10 C/minPlastic Polycarbonate · Max service temperature: UL 746B RTI, tensile strength, 1.5 mm
2
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
3
Engineering Polymers Part and Mold Design: Thermoplastics, A Design GuideCovestroarchived copyPlastic Polycarbonate · Poisson's ratio: typical, polycarbonate family (Covestro Part and Mold Design guide, Table 3-1)
4
Makrolon 2405 Data Sheet, ASTM valuesBayer MaterialSciencearchived copyPlastic Polycarbonate · Specific heat: typical (guide value), Bayer ASTM datasheet for Makrolon 2405, ASTM D 2766

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 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 is more ductile, Plastic PMMA or Plastic Polycarbonate?

Plastic Polycarbonate stretches further before it breaks: 125% elongation at break against 5.5% for Plastic PMMA.

Thermal

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.