Polypropylene (PP)
Semi-crystalline commodity thermoplastic; low density, good chemical resistance, low Tg.
Also called: polypropylene, PP, polypropene
| Property | Value | Source | Method | Conditions | Note |
|---|---|---|---|---|---|
| Density | 0.905 g/cm³ | Callister & Rethwisch, Materials Science and Engineering, 10th ed. | ASTM D792 | 23 °C, dry | — |
| Young's modulus E | 1.4 GPa | Callister & Rethwisch, Materials Science and Engineering, 10th ed. | ASTM D638 | 23 °C, dry | 1.1–1.6 typical range |
| Tensile strength | 34 MPa | Callister & Rethwisch, Materials Science and Engineering, 10th ed. | ASTM D638 | 23 °C, dry | — |
| Glass transition Tg | -10 °C | Callister & Rethwisch, Materials Science and Engineering, 10th ed. | DSC | 23 °C, dry | — |
| Melting point Tm | 165 °C | Callister & Rethwisch, Materials Science and Engineering, 10th ed. | DSC | 23 °C, dry | — |
About Polypropylene
Polypropylene is a commodity semi-crystalline thermoplastic and one of the highest-volume plastics in the world. It is very low density — about 0.905 g/cm³, so it floats — cheap, and highly resistant to chemicals and fatigue.
That fatigue resistance makes it the go-to for living hinges (the flexible fold in a flip-top cap) that survive millions of cycles. Its low glass transition (around −10 °C) means it turns brittle in the cold, which is its main limitation.
It dominates packaging, automotive interiors and battery cases, textiles, and household goods.
Used in
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Sources
- Callister & Rethwisch, Materials Science and Engineering, 10th ed.
Typical room-temperature values for learning and preliminary design; grades vary. Always confirm against the supplier datasheet before design work. Data policy: docs/DATA-SOURCES.md in the repository.