1100-O (annealed) commercially pure aluminium, Kaiser Aluminum Tube & Pipe Alloy 1100 Technical Data (Rev. 05/06), typical properties; specific heat from Hydro EN AW-1050A (99.5% Al) extruded-products datasheet (10/2018).
LyondellBasell Hostalen 23050 B high density polyethylene, typical ISO values
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 Aluminum 1100-O stronger than Plastic HDPE?
Aluminum 1100-O is stronger: its yield strength is 35 MPa against 24 MPa for Plastic HDPE (46%).
Which is lighter, Aluminum 1100-O or Plastic HDPE?
Plastic HDPE is lighter: 950 kg/m³ against 2,710 kg/m³ for Aluminum 1100-O.
Which is stiffer, Aluminum 1100-O or Plastic HDPE?
Aluminum 1100-O is stiffer: Young's modulus 69 GPa against 0.9 GPa for Plastic HDPE, so the same part in Aluminum 1100-O deflects less under the same load.
Which is lighter for the same job, Aluminum 1100-O or Plastic HDPE?
For the same stiffness or strength: Aluminum 1100-O is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate; Plastic HDPE is lighter for a strong rod or tie, strong beam, strong panel or plate.
Part that must be
Aluminum 1100-O
Plastic HDPE
Stiff rod or tie (tension)
lighter
26.9x heavier
Stiff beam (bending)
lighter
3.07x heavier
Stiff panel or plate
lighter
49% heavier
Strong rod or tie
1.96x heavier
lighter
Strong beam
2.22x heavier
lighter
Strong panel or plate
2.36x 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).
Which conducts heat better, Aluminum 1100-O or Plastic HDPE?
Aluminum 1100-O conducts heat better: 222 W/m·K against 0.445 W/m·K for Plastic HDPE.
Which expands less with temperature?
Aluminum 1100-O expands less: 23.6 µm/m·K against 120 µm/m·K for Plastic HDPE.