Plastic Polypropylene vs. Plastic UHMWPE

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

Plastic PolypropyleneBulk polymer (molded or machined)

Plastic UHMWPEBulk polymer (molded or machined)

Mechanical	Plastic Polypropylene	Plastic UHMWPE
Yield strength	33MPa11.65x stronger	20MPa2
Ultimate tensile strength	not stated (yield given)	43MPa2
Elongation at break	not sourced	465%2
Young's modulus (stiffness)	1.45GPa12.2x stiffer	0.66GPa2
Density	900kg/m³1	930kg/m³2
Strength to weight	36.7kN·m/kg1.71x higher	21.5kN·m/kg
Stiffness to weight	1.61MN·m/kg2.27x higher	0.71MN·m/kg
Poisson's ratio	base material0.423	not sourced
Shear modulus	0.511GPa	not sourced
Bulk modulus	3.02GPa	not sourced
Speed of sound	1,269m/s1.51x 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 Polypropylene	Plastic UHMWPE
Thermal conductivity	base material0.17–0.22W/m·K3	0.4W/m·K4
Thermal expansion	base material80–100µm/m·K3	200µm/m·K4
100 mm part over a 50 °C swing	450µm growth2.22x less	1,000µm growth
Specific heat	not sourced	not sourced
Heats up and cools (diffusivity)	not sourced	not sourced
Thermal shock resistance	28.6W/m	not sourced
Melting point	not sourced	DSC 10 K/min130–138°C2
Max service temperature	HDT 0.45 MPa90°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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Sources4 documents: LyondellBasell, Celanese, INEOS Olefins & Polymers USA

Plastic Polypropylene: LyondellBasell Moplen HP501H polypropylene homopolymer (general purpose), 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
Moplen HP501H Product DataLyondellBasellPlastic Polypropylene · Yield strength: typical, tensile stress at yield ISO 527Plastic Polypropylene · Young's modulus (stiffness): typical, tensile modulus ISO 527Plastic Polypropylene · Density: typical, 23 °C ISO 1183-1Plastic Polypropylene · Max service temperature: HDT 0.45 MPa (ISO 75B), unannealed
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 PolypropyleneINEOS Olefins & Polymers USAarchived copyPlastic Polypropylene · Poisson's ratio: base material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene)Plastic Polypropylene · Thermal conductivity: base material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene)Plastic Polypropylene · Thermal expansion: base material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene)
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 Polypropylene stronger than Plastic UHMWPE?

Plastic Polypropylene is stronger: its yield strength is 33 MPa against 20 MPa for Plastic UHMWPE (1.65x).

Which is lighter, Plastic Polypropylene or Plastic UHMWPE?

Plastic Polypropylene is lighter: 900 kg/m³ against 930 kg/m³ for Plastic UHMWPE.

Which is stiffer, Plastic Polypropylene or Plastic UHMWPE?

Plastic Polypropylene is stiffer: Young's modulus 1.45 GPa against 0.66 GPa for Plastic UHMWPE, so the same part in Plastic Polypropylene deflects less under the same load.

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

For the same stiffness or strength: Plastic Polypropylene 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 Polypropylene	Plastic UHMWPE
Stiff rod or tie (tension)	lighter	2.27x heavier
Stiff beam (bending)	lighter	1.53x heavier
Stiff panel or plate	lighter	34% heavier
Strong rod or tie	lighter	1.7x heavier
Strong beam	lighter	44% heavier
Strong panel or plate	lighter	33% 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 Polypropylene or Plastic UHMWPE?

Plastic UHMWPE conducts heat better: 0.4 W/m·K against 0.195 W/m·K for Plastic Polypropylene.

Which expands less with temperature?

Plastic Polypropylene expands less: 90 µm/m·K against 200 µm/m·K for Plastic UHMWPE.