Plastic Nylon PA66 vs. Plastic PMMA

Compare Plastic Nylon PA66 vs. Plastic PMMA strength, stiffness, weight and thermal properties.

Plastic Nylon PA66Bulk polymer (molded or machined)

Plastic PMMABulk polymer (molded or machined)

Mechanical	Plastic Nylon PA66	Plastic PMMA
Yield strength	85MPa1	not given (tensile used)
Ultimate tensile strength	not stated (yield given)	80MPa2
Compressive strength	not sourced	110MPa2
Flexural strength	not sourced	115MPa2
Elongation at break	30%15.45x more ductile	5.5%2
Young's modulus (stiffness)	3GPa1	3.3GPa2
Density	1,130kg/m³1	1,190kg/m³2
Strength to weight	75.2kN·m/kg12% higher	67.2kN·m/kg
Stiffness to weight	2.65MN·m/kg	2.77MN·m/kg4% higher
Poisson's ratio	base material0.43	0.372
Shear modulus	1.07GPa	1.2GPa12% stiffer in shear
Bulk modulus	5GPa18% higher	4.23GPa
Speed of sound	1,629m/s	1,665m/s2% faster

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal	Plastic Nylon PA66	Plastic PMMA
Thermal conductivity	0.33W/m·K11.74x more heat through a fin	0.19W/m·K2
Thermal expansion	longitudinal98µm/m·K1	0-50 °C70µm/m·K240% less
100 mm part over a 50 °C swing	490µm growth	350µm growth40% less
Specific heat	1,700J/kg·K116% higher	1,470J/kg·K2
Heats up and cools (diffusivity)	0.172mm²/s1.58x faster	0.109mm²/s
Thermal shock resistance	57.2W/m38% more resistant	41.5W/m
Melting point	DSC260°C1	not sourced
Max service temperature	101°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: BASF, Röhm, Covestro

Plastic Nylon PA66: BASF Ultramid A3K (PA66, unreinforced injection-moulding grade), Product Information 02/2026, dry values (ISO methods)
Plastic PMMA: Röhm PLEXIGLAS GS 0F00 cast acrylic sheet, typical values at 23 °C / 50 % RH (Röhm Technical Information Ref. No. 211-1)

1
Ultramid A3K Product InformationBASFPlastic Nylon PA66 · Yield strength: typical, dryPlastic Nylon PA66 · Elongation at break: nominal strain at break, dryPlastic Nylon PA66 · Young's modulus (stiffness): typical, dryPlastic Nylon PA66 · Density: typicalPlastic Nylon PA66 · Thermal conductivity: typicalPlastic Nylon PA66 · Thermal expansion: longitudinal, 23-55 °CPlastic Nylon PA66 · Specific heat: typicalPlastic Nylon PA66 · Melting point: DSCPlastic Nylon PA66 · Max service temperature: IEC 60216 temperature index, 20000 h
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 GuideCovestroPlastic Nylon PA66 · Poisson's ratio: base material: unfilled polyamide (PA), conditioned, maker design-guide family value (Covestro Table 3-1)

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 Nylon PA66 stronger than Plastic PMMA?

Plastic Nylon PA66 is stronger: its yield strength is 85 MPa against tensile strength 80 MPa for Plastic PMMA (6%).

Which is lighter, Plastic Nylon PA66 or Plastic PMMA?

Plastic Nylon PA66 is lighter: 1,130 kg/m³ against 1,190 kg/m³ for Plastic PMMA.

Which is stiffer, Plastic Nylon PA66 or Plastic PMMA?

Plastic PMMA is stiffer: Young's modulus 3.3 GPa against 3 GPa for Plastic Nylon PA66, so the same part in Plastic PMMA deflects less under the same load.

Which is lighter for the same job, Plastic Nylon PA66 or Plastic PMMA?

For the same stiffness or strength: Plastic Nylon PA66 is lighter for a stiff panel or plate, strong rod or tie, strong beam, strong panel or plate; Plastic PMMA is lighter for a stiff rod or tie (tension).

Part that must be	Plastic Nylon PA66	Plastic PMMA
Stiff rod or tie (tension)	4% heavier	lighter
Stiff beam (bending)	about equal	about equal
Stiff panel or plate	lighter	2% heavier
Strong rod or tie	lighter	12% heavier
Strong beam	lighter	10% heavier
Strong panel or plate	lighter	9% 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 Nylon PA66 or Plastic PMMA?

Plastic Nylon PA66 stretches further before it breaks: 30% elongation at break against 5.5% for Plastic PMMA.

Thermal

Which conducts heat better, Plastic Nylon PA66 or Plastic PMMA?

Plastic Nylon PA66 conducts heat better: 0.33 W/m·K against 0.19 W/m·K for Plastic PMMA.

Which expands less with temperature?

Plastic PMMA expands less: 70 µm/m·K against 98 µm/m·K for Plastic Nylon PA66.