Comparison of elastomeric materials for the manufacturing of functional dynamic seals
| Group of elastomers | Silicone (SIL) | Polyurethane (PU) |
|---|---|---|
| Product name | Smooth-Sil 950 | PMC-780 Dry |
| Polymerization issues | Cure inhibition | Side reaction, CO2 |
| Mixed viscosity (cps) | 35,000 | 2,000 |
| Pot life (min) | 45 | 25 |
| Cure time (h) | 18 | 48 |
| Hazardous components | – | Toluene diisocyanate |
| Shore A hardness | 50 | 80 |
| 100% modulus (MPa) | 1.9 | 2.8 |
| Elongation at break (%) | 320 | 750 |
| Tear strength (ppi) | 155 (Die B) | 200 (Die C) |
| Silicone (SIL) | Polyurethane (PU) | |
|---|---|---|
| Smooth-Sil 950 | PMC-780 Dry | |
| Cure inhibition | Side reaction, CO2 | |
| 35,000 | 2,000 | |
| 45 | 25 | |
| 18 | 48 | |
| – | Toluene diisocyanate | |
| 50 | 80 | |
| 1.9 | 2.8 | |
| 320 | 750 | |
| 155 (Die B) | 200 (Die C) |
Notes:
Values were taken from material data sheets (Smooth-On, Inc., 2022a, 2022b) and material safety datasheets (Smooth-On, Inc., 2020, 2021)
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