Plastic PETG vs. Plastic PMMA

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

Plastic PMMABulk polymer (molded or machined)

Mechanical	Plastic PETG	Plastic PMMA
Yield strength	46.2MPa1	not given (tensile used)
Ultimate tensile strength	46.2MPa1	80MPa21.73x stronger
Compressive strength	not sourced	110MPa2
Flexural strength	78.9MPa1	115MPa246% stronger in bending
Elongation at break	7.6%138% more ductile	5.5%2
Young's modulus (stiffness)	1.94GPa1	3.3GPa21.7x stiffer
Density	1,270kg/m³1	1,190kg/m³2
Strength to weight	36.4kN·m/kg	67.2kN·m/kg1.85x higher
Stiffness to weight	1.53MN·m/kg	2.77MN·m/kg1.82x higher
Poisson's ratio	not sourced	0.372
Shear modulus	not sourced	1.2GPa
Bulk modulus	not sourced	4.23GPa
Speed of sound	1,236m/s	1,665m/s35% faster

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal	Plastic PETG	Plastic PMMA
Thermal conductivity	base material0.21W/m·K3	0.19W/m·K2
Thermal expansion	base material51µm/m·K337% less	0-50 °C70µm/m·K2
100 mm part over a 50 °C swing	255µm growth37% less	350µm growth
Specific heat	base material1,300J/kg·K3	1,470J/kg·K213% higher
Heats up and cools (diffusivity)	0.127mm²/s17% faster	0.109mm²/s
Thermal shock resistance	not sourced	41.5W/m
Glass transition	77.4°C1	not sourced
Max service temperature	HDT 0.455 MPa76.2°C1	80°C2

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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Sources3 documents: UltiMaker, Röhm, Eastman

Plastic PETG: Ultimaker PETG, 3D-printed specimens, XY (flat); Ultimaker S5 Pro, engineering intent profile, 0.15 mm layer height, AA 0.4 print core, 100% infill, Cura 4.9, printed one-at-a-time, conditioned >=24 h at room temperature. TDS v1.00, April 29, 2022.
Plastic PMMA: Röhm PLEXIGLAS GS 0F00 cast acrylic sheet, typical values at 23 °C / 50 % RH (Röhm Technical Information Ref. No. 211-1)

1
Ultimaker PETG Technical Data Sheet, v1.00UltiMakerarchived copyPlastic PETG · Yield strength: typicalPlastic PETG · Ultimate tensile strength: typical, peak stress (= stress at yield)Plastic PETG · Flexural strength: typicalPlastic PETG · Elongation at break: typicalPlastic PETG · Young's modulus (stiffness): typicalPlastic PETG · Density: typicalPlastic PETG · Glass transition: typicalPlastic PETG · Max service temperature: HDT 0.455 MPa (printed specimens)
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
Eastar Copolyester 6763 Product Data SheetEastmanPlastic PETG · Thermal conductivity: base material: Eastman Eastar Copolyester 6763 (PETG), typicalPlastic PETG · Thermal expansion: base material: Eastman Eastar Copolyester 6763 (PETG), typicalPlastic PETG · Specific heat: base material: Eastman Eastar Copolyester 6763 (PETG), DSC at 60 °C (lowest temperature listed)

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.

Plastic PETG is 3D printed: its properties depend on build direction and print settings; these are typical values.

Questions

Mechanical

Is Plastic PETG stronger than Plastic PMMA?

Plastic PMMA is stronger: its tensile strength is 80 MPa against yield strength 46.2 MPa for Plastic PETG (1.73x).

Which is lighter, Plastic PETG or Plastic PMMA?

Plastic PMMA is lighter: 1,190 kg/m³ against 1,270 kg/m³ for Plastic PETG.

Which is stiffer, Plastic PETG or Plastic PMMA?

Plastic PMMA is stiffer: Young's modulus 3.3 GPa against 1.94 GPa for Plastic PETG, so the same part in Plastic PMMA deflects less under the same load.

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

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 PETG	Plastic PMMA
Stiff rod or tie (tension)	1.82x heavier	lighter
Stiff beam (bending)	39% heavier	lighter
Stiff panel or plate	27% heavier	lighter
Strong rod or tie	1.85x heavier	lighter
Strong beam	1.54x heavier	lighter
Strong panel or plate	40% 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 PETG or Plastic PMMA?

Plastic PETG stretches further before it breaks: 7.6% elongation at break against 5.5% for Plastic PMMA.

Thermal

Which conducts heat better, Plastic PETG or Plastic PMMA?

Plastic PETG conducts heat better: 0.21 W/m·K against 0.19 W/m·K for Plastic PMMA.

Which expands less with temperature?

Plastic PETG expands less: 51 µm/m·K against 70 µm/m·K for Plastic PMMA.