Plastic PLA vs. Plastic PMMA

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

Plastic PMMABulk polymer (molded or machined)

Mechanical	Plastic PLA	Plastic PMMA
Yield strength	52.5MPa1	not given (tensile used)
Ultimate tensile strength	52.5MPa1	80MPa21.52x stronger
Compressive strength	not sourced	110MPa2
Flexural strength	96.8MPa1	115MPa219% stronger in bending
Elongation at break	7.8%142% more ductile	5.5%2
Young's modulus (stiffness)	3.25GPa1	3.3GPa2
Density	1,240kg/m³1	1,190kg/m³2
Strength to weight	42.3kN·m/kg	67.2kN·m/kg1.59x higher
Stiffness to weight	2.62MN·m/kg	2.77MN·m/kg6% higher
Poisson's ratio	not sourced	0.372
Shear modulus	not sourced	1.2GPa
Bulk modulus	not sourced	4.23GPa
Speed of sound	1,619m/s	1,665m/s3% faster

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal	Plastic PLA	Plastic PMMA
Thermal conductivity	base material0.13W/m·K3	0.19W/m·K246% more heat through a fin
Thermal expansion	not sourced	0-50 °C70µm/m·K2
100 mm part over a 50 °C swing	not sourced	350µm growth
Specific heat	base material1,200J/kg·K3	1,470J/kg·K223% higher
Heats up and cools (diffusivity)	0.0874mm²/s	0.109mm²/s24% faster
Thermal shock resistance	not sourced	41.5W/m
Melting point	152°C1	not sourced
Glass transition	59.1°C1	not sourced
Max service temperature	HDT 0.455 MPa58.8°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, NatureWorks

Plastic PLA: Ultimaker PLA, 3D-printed specimens, XY (flat) orientation; 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 dated April 20, 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 PLA Technical Data Sheet, v5.00UltiMakerarchived copyPlastic PLA · Yield strength: typicalPlastic PLA · Ultimate tensile strength: typical, peak stress (= stress at yield)Plastic PLA · Flexural strength: typicalPlastic PLA · Elongation at break: typicalPlastic PLA · Young's modulus (stiffness): typicalPlastic PLA · Density: typicalPlastic PLA · Melting point: typicalPlastic PLA · Glass transition: typicalPlastic PLA · 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
Engineering Properties of Ingeo BiopolymerNatureWorksarchived copyPlastic PLA · Thermal conductivity: base material: NatureWorks Ingeo biopolymer, amorphous sheet, 25 °CPlastic PLA · Specific heat: base material: NatureWorks Ingeo biopolymer, amorphous sheet, 25 °C

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

Questions

Mechanical

Is Plastic PLA stronger than Plastic PMMA?

Plastic PMMA is stronger: its tensile strength is 80 MPa against yield strength 52.5 MPa for Plastic PLA (1.52x).

Which is lighter, Plastic PLA or Plastic PMMA?

Plastic PMMA is lighter: 1,190 kg/m³ against 1,240 kg/m³ for Plastic PLA.

Which is stiffer, Plastic PLA or Plastic PMMA?

Plastic PMMA is stiffer: Young's modulus 3.3 GPa against 3.25 GPa for Plastic PLA, so the same part in Plastic PMMA deflects less under the same load.

Which is lighter for the same job, Plastic PLA 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 PLA	Plastic PMMA
Stiff rod or tie (tension)	6% heavier	lighter
Stiff beam (bending)	5% heavier	lighter
Stiff panel or plate	5% heavier	lighter
Strong rod or tie	1.59x heavier	lighter
Strong beam	38% heavier	lighter
Strong panel or plate	29% 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 PLA or Plastic PMMA?

Plastic PLA stretches further before it breaks: 7.8% elongation at break against 5.5% for Plastic PMMA.

Thermal

Which conducts heat better, Plastic PLA or Plastic PMMA?

Plastic PMMA conducts heat better: 0.19 W/m·K against 0.13 W/m·K for Plastic PLA.