Plastic HDPE vs. SLS PA12 Nylon

Compare Plastic HDPE vs. SLS PA12 Nylon strength, stiffness, weight and thermal properties.

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Plastic HDPEBulk polymer (molded or machined)

Mechanical
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Yield strength	24MPasourcetypical, tensile stress at yield 23 °C, 50 mm/min ISO 527	not given (tensile used)
Ultimate tensile strength	not sourced	48MPasourcetypical
Elongation at break	not sourced	18%sourcetypical
Young's modulus (stiffness)	0.9GPasourcetypical, tensile modulus 23 °C ISO 527	1.65GPasourcetypical
Density	950kg/m³sourcetypical, ISO 1183	930kg/m³sourcetypical
Strength to weight	25.3kN·m/kg	51.6kN·m/kg2.04x higher
Stiffness to weight	0.947MN·m/kg	1.77MN·m/kg1.87x higher
Poisson's ratio	0.4–0.45sourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE)	not sourced
Shear modulus	0.316GPa	not sourced
Bulk modulus	2GPa	not sourced
Speed of sound	973m/s	1,332m/s
Thermal
Thermal conductivity	0.4–0.49W/m·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE)	not sourced
Thermal expansion	120µm/m·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE)	not sourced
100 mm part over a 50 °C swing	600µm growth	not sourced
Specific heat	2,250J/kg·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE)	not sourced
Heats up and cools (diffusivity)	0.208mm²/s	not sourced
Thermal shock resistance	56.9W/m	not sourced
Melting point	not sourced	176°Csourcetypical
Max service temperature	not sourced	64°CsourceHDT 1.8 MPa, X orientation
Values for	LyondellBasell Hostalen 23050 B high density polyethylene, typical ISO values	EOS PA 2200 (PA12) Material Data Sheet, process parameter 'Balance' at 120 µm layer thickness, X orientation, dry (conditioned values not given). Live MDS status 04.10.2026, last changed 10.09.2026; PDF via ?topdf=... link on the same page.

Every value links to the document that states it. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.

SLS PA12 Nylon is 3D printed: its properties depend on build direction and print settings; these are typical values.

Questions

Is Plastic HDPE stronger than SLS PA12 Nylon?

SLS PA12 Nylon is stronger: its tensile strength is 48 MPa against yield strength 24 MPa for Plastic HDPE (2x).

Which is lighter, Plastic HDPE or SLS PA12 Nylon?

SLS PA12 Nylon is lighter: 930 kg/m³ against 950 kg/m³ for Plastic HDPE.

Which is stiffer, Plastic HDPE or SLS PA12 Nylon?

SLS PA12 Nylon is stiffer: Young's modulus 1.65 GPa against 0.9 GPa for Plastic HDPE, so the same part in SLS PA12 Nylon deflects less under the same load.

Which is lighter for the same job, Plastic HDPE or SLS PA12 Nylon?

For the same stiffness or strength: SLS PA12 Nylon 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	SLS PA12 Nylon
Stiff rod or tie (tension)	1.87x heavier	lighter
Stiff beam (bending)	38% heavier	lighter
Stiff panel or plate	25% heavier	lighter
Strong rod or tie	2.04x heavier	lighter
Strong beam	1.62x heavier	lighter
Strong panel or plate	44% 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).

Among 72 materials

Stiffness against density

Strength against density