Plastic HDPE vs. Plastic Nylon PA6

Compare Plastic HDPE vs. Plastic Nylon PA6 strength, stiffness, weight and thermal properties.

Plastic HDPEBulk polymer (molded or machined)

Plastic Nylon PA6Bulk polymer (molded or machined)

Mechanical	Plastic HDPE	Plastic Nylon PA6
Yield strength	24MPa1	90MPa23.75x stronger
Ultimate tensile strength	not stated (yield given)	not stated (yield given)
Elongation at break	not sourced	10%2
Young's modulus (stiffness)	0.9GPa1	3.5GPa23.89x stiffer
Density	950kg/m³119% lighter	1,130kg/m³2
Strength to weight	25.3kN·m/kg	79.6kN·m/kg3.15x higher
Stiffness to weight	0.947MN·m/kg	3.1MN·m/kg3.27x higher
Poisson's ratio	base material0.4–0.453	base material0.44
Shear modulus	0.316GPa	1.25GPa3.96x stiffer in shear
Bulk modulus	2GPa	5.83GPa2.92x higher
Speed of sound	973m/s	1,760m/s1.81x faster

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal	Plastic HDPE	Plastic Nylon PA6
Thermal conductivity	base material0.4–0.49W/m·K3	0.33W/m·K2
Thermal expansion	base material120µm/m·K3	longitudinal102µm/m·K218% less
100 mm part over a 50 °C swing	600µm growth	510µm growth18% less
Specific heat	base material2,250J/kg·K332% higher	1,700J/kg·K2
Heats up and cools (diffusivity)	0.208mm²/s21% faster	0.172mm²/s
Thermal shock resistance	56.9W/m14% more resistant	49.9W/m
Melting point	not sourced	DSC220°C2
Max service temperature	not sourced	87°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

Try it on a partA bracket to run stress or thermal on, free in your browser	Open in LessCAD	Open in LessCAD

Sources4 documents: LyondellBasell, BASF, INEOS Olefins & Polymers USA, Covestro

Plastic HDPE: LyondellBasell Hostalen 23050 B high density polyethylene, typical ISO values
Plastic Nylon PA6: BASF Ultramid B3S (PA6, unreinforced injection-moulding grade), Product Information 02/2026, dry values (ISO methods)

1
Hostalen 23050 B Product DataLyondellBasellPlastic HDPE · Yield strength: typical, tensile stress at yield 23 °C, 50 mm/min ISO 527Plastic HDPE · Young's modulus (stiffness): typical, tensile modulus 23 °C ISO 527Plastic HDPE · Density: typical, ISO 1183
2
Ultramid B3S Product InformationBASFPlastic Nylon PA6 · Yield strength: typical, dryPlastic Nylon PA6 · Elongation at break: nominal strain at break, dryPlastic Nylon PA6 · Young's modulus (stiffness): typical, dryPlastic Nylon PA6 · Density: typicalPlastic Nylon PA6 · Thermal conductivity: typicalPlastic Nylon PA6 · Thermal expansion: longitudinal, 23-55 °CPlastic Nylon PA6 · Specific heat: typicalPlastic Nylon PA6 · Melting point: DSCPlastic Nylon PA6 · Max service temperature: IEC 60216 temperature index, 20000 h
3
Typical Engineering Properties of High Density PolyethyleneINEOS Olefins & Polymers USAarchived copyPlastic HDPE · Poisson's ratio: base material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE)Plastic HDPE · Thermal conductivity: base material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE)Plastic HDPE · Thermal expansion: base material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE)Plastic HDPE · Specific heat: base material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE)
4
Engineering Polymers Part and Mold Design: Thermoplastics, A Design GuideCovestroPlastic Nylon PA6 · 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 HDPE stronger than Plastic Nylon PA6?

Plastic Nylon PA6 is stronger: its yield strength is 90 MPa against 24 MPa for Plastic HDPE (3.75x).

Which is lighter, Plastic HDPE or Plastic Nylon PA6?

Plastic HDPE is lighter: 950 kg/m³ against 1,130 kg/m³ for Plastic Nylon PA6.

Which is stiffer, Plastic HDPE or Plastic Nylon PA6?

Plastic Nylon PA6 is stiffer: Young's modulus 3.5 GPa against 0.9 GPa for Plastic HDPE, so the same part in Plastic Nylon PA6 deflects less under the same load.

Which is lighter for the same job, Plastic HDPE or Plastic Nylon PA6?

For the same stiffness or strength: Plastic Nylon PA6 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 HDPE	Plastic Nylon PA6
Stiff rod or tie (tension)	3.27x heavier	lighter
Stiff beam (bending)	1.66x heavier	lighter
Stiff panel or plate	32% heavier	lighter
Strong rod or tie	3.15x heavier	lighter
Strong beam	2.03x heavier	lighter
Strong panel or plate	1.63x 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).

Thermal

Which conducts heat better, Plastic HDPE or Plastic Nylon PA6?

Plastic HDPE conducts heat better: 0.445 W/m·K against 0.33 W/m·K for Plastic Nylon PA6.

Which expands less with temperature?

Plastic Nylon PA6 expands less: 102 µm/m·K against 120 µm/m·K for Plastic HDPE.