Plastic HDPE vs. Plastic UHMWPE

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

Plastic HDPEBulk polymer (molded or machined)

Plastic UHMWPEBulk polymer (molded or machined)

Mechanical	Plastic HDPE	Plastic UHMWPE
Yield strength	24MPa120% stronger	20MPa2
Ultimate tensile strength	not stated (yield given)	43MPa2
Elongation at break	not sourced	465%2
Young's modulus (stiffness)	0.9GPa136% stiffer	0.66GPa2
Density	950kg/m³1	930kg/m³2
Strength to weight	25.3kN·m/kg17% higher	21.5kN·m/kg
Stiffness to weight	0.947MN·m/kg33% higher	0.71MN·m/kg
Poisson's ratio	base material0.4–0.453	not sourced
Shear modulus	0.316GPa	not sourced
Bulk modulus	2GPa	not sourced
Speed of sound	973m/s16% faster	842m/s

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal	Plastic HDPE	Plastic UHMWPE
Thermal conductivity	base material0.4–0.49W/m·K3	0.4W/m·K4
Thermal expansion	base material120µm/m·K31.67x less	200µm/m·K4
100 mm part over a 50 °C swing	600µm growth1.67x less	1,000µm growth
Specific heat	base material2,250J/kg·K3	not sourced
Heats up and cools (diffusivity)	0.208mm²/s	not sourced
Thermal shock resistance	56.9W/m	not sourced
Melting point	not sourced	DSC 10 K/min130–138°C2
Max service temperature	not sourced	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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Sources4 documents: LyondellBasell, Celanese, INEOS Olefins & Polymers USA

Plastic HDPE: LyondellBasell Hostalen 23050 B high density polyethylene, typical ISO values
Plastic UHMWPE: Celanese GUR 4120 (avg. molecular weight 4.7x10^6 g/mol), typical values on compression-molded specimens; CTE and thermal conductivity from Celanese's generic UHMWPE guide (grade not named)

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
GUR UHMW-PE Overview (GUR-015)CelanesePlastic UHMWPE · Yield strength: typical, tensile stress at yield ISO 527, 50 mm/minPlastic UHMWPE · Ultimate tensile strength: typical, tensile stress at break ISO 527, 50 mm/minPlastic UHMWPE · Elongation at break: typical, nominal elongation at break ISO 527Plastic UHMWPE · Young's modulus (stiffness): typical, tensile modulus ISO 527, 1 mm/minPlastic UHMWPE · Density: typicalPlastic UHMWPE · Melting point: DSC 10 K/minPlastic UHMWPE · Max service temperature: recommended max constant operating temperature
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
GUR UHMW-PE Polymer Guide (GUR-003)Celanesearchived copyPlastic UHMWPE · Thermal conductivity: typical, unfilled (narrative value, generic Celanese UHMWPE)Plastic UHMWPE · Thermal expansion: typical, 20 to 100 °C (generic Celanese UHMWPE)

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 UHMWPE?

Plastic HDPE is stronger: its yield strength is 24 MPa against 20 MPa for Plastic UHMWPE (20%).

Which is lighter, Plastic HDPE or Plastic UHMWPE?

Plastic UHMWPE is lighter: 930 kg/m³ against 950 kg/m³ for Plastic HDPE.

Which is stiffer, Plastic HDPE or Plastic UHMWPE?

Plastic HDPE is stiffer: Young's modulus 0.9 GPa against 0.66 GPa for Plastic UHMWPE, so the same part in Plastic HDPE deflects less under the same load.

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

For the same stiffness or strength: Plastic HDPE 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 UHMWPE
Stiff rod or tie (tension)	lighter	33% heavier
Stiff beam (bending)	lighter	14% heavier
Stiff panel or plate	lighter	9% heavier
Strong rod or tie	lighter	17% heavier
Strong beam	lighter	11% heavier
Strong panel or plate	lighter	7% 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).

Thermal

Which conducts heat better, Plastic HDPE or Plastic UHMWPE?

Plastic HDPE conducts heat better: 0.445 W/m·K against 0.4 W/m·K for Plastic UHMWPE.

Which expands less with temperature?

Plastic HDPE expands less: 120 µm/m·K against 200 µm/m·K for Plastic UHMWPE.