Plastic POM/Acetal vs. Plastic UHMWPE

Compare Plastic POM/Acetal vs. Plastic UHMWPE strength, stiffness, weight and thermal properties.

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Plastic POM/AcetalBulk polymer (molded or machined)

Plastic UHMWPEBulk polymer (molded or machined)

Mechanical
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Yield strength	69MPasourcetypical (single ASTM D638 tensile strength)	20MPasourcetypical, tensile stress at yield ISO 527, 50 mm/min
Ultimate tensile strength	69MPasourcetypical	43MPasourcetypical, tensile stress at break ISO 527, 50 mm/min
Compressive strength	124MPasourcecompressive stress at 10% deformation	not sourced
Flexural strength	99MPasourceflexural yield strength, typical	not sourced
Elongation at break	75%sourcetypical	465%sourcetypical, nominal elongation at break ISO 527
Young's modulus (stiffness)	2.8GPasourcetypical	0.66GPasourcetypical, tensile modulus ISO 527, 1 mm/min
Density	1,420kg/m³sourcetypical (DuPont product information for Delrin 100 NC010; 'The data listed here fall within the normal range of product properties')	930kg/m³sourcetypical
Strength to weight	48.6kN·m/kg2.26x higher	21.5kN·m/kg
Stiffness to weight	1.97MN·m/kg2.78x higher	0.71MN·m/kg
Poisson's ratio	0.35sourcetypical	not sourced
Shear modulus	1.04GPa	not sourced
Bulk modulus	3.11GPa	not sourced
Speed of sound	1,404m/s	842m/s
Thermal
Thermal conductivity	0.4W/m·Ksourcetypical	0.4W/m·Ksourcetypical, unfilled (narrative value, generic Celanese UHMWPE)
Thermal expansion	122µm/m·Ksourcemean, 29 to 60 °C	200µm/m·Ksourcetypical, 20 to 100 °C (generic Celanese UHMWPE)
100 mm part over a 50 °C swing	610µm growth1.64x less	1,000µm growth
Specific heat	1,465J/kg·Ksourceaverage -18 to 100 °C, Delrin acetal resins (not grade-specific)	not sourced
Heats up and cools (diffusivity)	0.192mm²/s	not sourced
Thermal shock resistance	52.5W/m	not sourced
Melting point	175°Csourcecrystalline melting point	130–138°CsourceDSC 10 K/min
Max service temperature	125°CsourceHDT 1.8 MPa (annealed)	80°Csourcerecommended max constant operating temperature
Values for	DuPont Delrin 100 acetal homopolymer, Table 2 'Typical Properties of Delrin Acetal Resins' (ASTM methods), Delrin Design Guide Module III hosted on delrin.com	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)

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.

Questions

Is Plastic POM/Acetal stronger than Plastic UHMWPE?

Plastic POM/Acetal is stronger: its yield strength is 69 MPa against 20 MPa for Plastic UHMWPE (3.45x).

Which is lighter, Plastic POM/Acetal or Plastic UHMWPE?

Plastic UHMWPE is lighter: 930 kg/m³ against 1,420 kg/m³ for Plastic POM/Acetal.

Which is stiffer, Plastic POM/Acetal or Plastic UHMWPE?

Plastic POM/Acetal is stiffer: Young's modulus 2.8 GPa against 0.66 GPa for Plastic UHMWPE, so the same part in Plastic POM/Acetal deflects less under the same load.

Which is lighter for the same job, Plastic POM/Acetal or Plastic UHMWPE?

For the same stiffness or strength: Plastic POM/Acetal 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 POM/Acetal	Plastic UHMWPE
Stiff rod or tie (tension)	lighter	2.78x heavier
Stiff beam (bending)	lighter	35% heavier
Stiff panel or plate	lighter	6% heavier
Strong rod or tie	lighter	2.26x heavier
Strong beam	lighter	50% heavier
Strong panel or plate	lighter	22% 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 conducts heat better, Plastic POM/Acetal or Plastic UHMWPE?

Plastic POM/Acetal conducts heat better: 0.4 W/m·K against 0.4 W/m·K for Plastic UHMWPE.

Which expands less with temperature?

Plastic POM/Acetal expands less: 122 µm/m·K against 200 µm/m·K for Plastic UHMWPE.

Among 72 materials

Stiffness against density

Strength against density