PLA vs Polypropylene
PLA and Polypropylene are genuine alternatives to one another — a choice somebody actually makes — and differ on 1 measured property, density most clearly.
PLA vs Polypropylene
PLA
Made from sugar rather than oil, and compostable in an industrial composter and almost nowhere else.
Polypropylene
The lightest common plastic, and the only one that survives being bent forever — the living hinge, the food tub, and half the world's rope.
| Property | PLA | Polypropylene |
|---|---|---|
| Density | 1.24–1.27 g/cm³ higher | 0.895–0.92 g/cm³ |
| Melting point Only one of the two has a figure we can stand behind, so there is nothing to compare. | Not known | 160–171 °C |
| Tensile strength Only one of the two has a figure we can stand behind, so there is nothing to compare. | 50–70 MPa | Not known |
| Young's modulus Only one of the two has a figure we can stand behind, so there is nothing to compare. | 3–3.8 GPa | Not known |
Choosing between them
PLA is recorded as a substitute for Polypropylene — lower environmental impact.
What it gives up: Softens near 60 °C, so it cannot hold a hot drink, survive a dishwasher or sit in a car in summer. It is also brittle, and it is a contaminant in the PET recycling stream.
Partial substitute, on the evidence cited above.