300°Csourceproducer's maximum application temperature (optical components)
Values for
Röhm PLEXIGLAS GS 0F00 cast acrylic sheet, typical values at 23 °C / 50 % RH (Röhm Technical Information Ref. No. 211-1)
Synthetic single-crystal silicon (cubic, diamond structure), Korth Kristalle (crystal grower) material data; Korth usually supplies Floating Zone (FZ) material, Czochralski (Cz) also offered. Silicon is elastically anisotropic; the producer quotes one modulus and the solver is isotropic.
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 PMMA stronger than Silicon?
Silicon is stronger: its tensile strength is 130 MPa against 80 MPa for Plastic PMMA (1.63x).
Which is lighter, Plastic PMMA or Silicon?
Plastic PMMA is lighter: 1,190 kg/m³ against 2,329 kg/m³ for Silicon.
Which is stiffer, Plastic PMMA or Silicon?
Silicon is stiffer: Young's modulus 131 GPa against 3.3 GPa for Plastic PMMA, so the same part in Silicon deflects less under the same load.
Which is lighter for the same job, Plastic PMMA or Silicon?
For the same stiffness or strength: Plastic PMMA is lighter for a strong rod or tie, strong beam, strong panel or plate; Silicon is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate.
Part that must be
Plastic PMMA
Silicon
Stiff rod or tie (tension)
20.3x heavier
lighter
Stiff beam (bending)
3.22x heavier
lighter
Stiff panel or plate
1.74x heavier
lighter
Strong rod or tie
lighter
20% heavier
Strong beam
lighter
42% heavier
Strong panel or plate
lighter
1.54x 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 PMMA or Silicon?
Silicon conducts heat better: 163 W/m·K against 0.19 W/m·K for Plastic PMMA.
Which expands less with temperature?
Silicon expands less: 2.62 µm/m·K against 70 µm/m·K for Plastic PMMA.