Plastic Polycarbonate vs. Plastic Polypropylene

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

Change either side

Plastic PolycarbonateBulk polymer (molded or machined)

Plastic PolypropyleneBulk polymer (molded or machined)

Mechanical
Try it on a partA bracket to run stress or thermal on, free in your browser	Open in LessCAD	Open in LessCAD
Yield strength	65MPasourcetypical, tensile yield	33MPasourcetypical, tensile stress at yield ISO 527
Ultimate tensile strength	65MPasourcetypical, stress at break	not sourced
Flexural strength	97MPasourcetypical, flexural strength	not sourced
Elongation at break	125%sourcetypical, strain at break	not sourced
Young's modulus (stiffness)	2.4GPasourcetypical	1.45GPasourcetypical, tensile modulus ISO 527
Density	1,200kg/m³sourcetypical	900kg/m³sourcetypical, 23 °C ISO 1183-1
Strength to weight	54.2kN·m/kg48% higher	36.7kN·m/kg
Stiffness to weight	2MN·m/kg24% higher	1.61MN·m/kg
Poisson's ratio	0.38sourcetypical, polycarbonate family (Covestro Part and Mold Design guide, Table 3-1)	0.42sourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene)
Shear modulus	0.87GPa1.7x stiffer in shear	0.511GPa
Bulk modulus	3.33GPa	3.02GPa
Speed of sound	1,414m/s	1,269m/s
Thermal
Thermal conductivity	0.2W/m·Ksourcetypical, through-plane, 23 C	0.17–0.22W/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene)
Thermal expansion	65µm/m·Ksourcetypical, 23-55 C, parallel and normal	80–100µm/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene)
100 mm part over a 50 °C swing	325µm growth38% less	450µm growth
Specific heat	1,172J/kg·Ksourcetypical (guide value), Bayer ASTM datasheet for Makrolon 2405, ASTM D 2766	not sourced
Heats up and cools (diffusivity)	0.142mm²/s	not sourced
Thermal shock resistance	51.7W/m1.81x more resistant	28.6W/m
Glass transition	144°Csourcetypical, DSC 10 C/min	not sourced
Max service temperature	125°CsourceUL 746B RTI, tensile strength, 1.5 mm	90°CsourceHDT 0.45 MPa (ISO 75B), unannealed
Values for	Covestro Makrolon 2405 general-purpose PC (MVR 19), Covestro technical datasheet version 2026-09-28, typical values	LyondellBasell Moplen HP501H polypropylene homopolymer (general purpose), 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 Plastic Polycarbonate stronger than Plastic Polypropylene?

Plastic Polycarbonate is stronger: its yield strength is 65 MPa against 33 MPa for Plastic Polypropylene (1.97x).

Which is lighter, Plastic Polycarbonate or Plastic Polypropylene?

Plastic Polypropylene is lighter: 900 kg/m³ against 1,200 kg/m³ for Plastic Polycarbonate.

Which is stiffer, Plastic Polycarbonate or Plastic Polypropylene?

Plastic Polycarbonate is stiffer: Young's modulus 2.4 GPa against 1.45 GPa for Plastic Polypropylene, so the same part in Plastic Polycarbonate deflects less under the same load.

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

For the same stiffness or strength: Plastic Polycarbonate is lighter for a stiff rod or tie (tension), strong rod or tie, strong beam, strong panel or plate; Plastic Polypropylene is lighter for a stiff beam (bending), stiff panel or plate.

Part that must be	Plastic Polycarbonate	Plastic Polypropylene
Stiff rod or tie (tension)	lighter	24% heavier
Stiff beam (bending)	4% heavier	lighter
Stiff panel or plate	13% heavier	lighter
Strong rod or tie	lighter	48% heavier
Strong beam	lighter	18% heavier
Strong panel or plate	lighter	5% 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 Polycarbonate or Plastic Polypropylene?

Plastic Polycarbonate conducts heat better: 0.2 W/m·K against 0.195 W/m·K for Plastic Polypropylene.

Which expands less with temperature?

Plastic Polycarbonate expands less: 65 µm/m·K against 90 µm/m·K for Plastic Polypropylene.

Among 59 materials

Stiffness against density

Strength against density