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Comparison of demolding, gel, and constant elongation strength of materials with different NCO contents_
| NCO (%) | Stripping time (min) | Gel time (min) | 300% Fixed extension strength (MPa) |
|---|---|---|---|
| 4.0 | 201.2 | 29.1 | 10.5 |
| 4.5 | 191.2 | 28.5 | 10.6 |
| 5.0 | 190.2 | 24.9 | 11.2 |
| 5.5 | 181.2 | 21.4 | 11.6 |
| 6.0 | 180.0 | 20.3 | 12.2 |
| 6.5 | 179.5 | 17.1 | 13.3 |
| 7.0 | 179.5 | 15.2 | 15.5 |
| 7.5 | 159.5 | 13.1 | 17.6 |
| 8.0 | 155.2 | 10.3 | 18.9 |
| 8.5 | 130.0 | 9.4 | 19.5 |
| 9.0 | 112.5 | 8.2 | 20.1 |
| 9.5 | 112.3 | 8.2 | 20.1 |
Properties of elastomeric materials under different catalyst types and dosages_
| Type | Without catalyst | Cat | Hb21 | |||
|---|---|---|---|---|---|---|
| Usage | — | 0.03% | 0.05% | 0.10% | 0.03% | 0.05% |
| Tensile strength (MPa) | 15.4 | 18.2 | 20.8 | 24.4 | 23.4 | — |
| Hardness (shore a) | 81.8 | 74.4 | 72.4 | 73.4 | 75.9 | — |
| Tensile elongation at break (%) | 260 | 389 | 374 | 378 | 407 | — |
| 300% tensile stress (MPa) | — | 9.1 | 11.8 | 12.0 | 9.6 | — |
| Demolding time (min) | 199 | 59 | 49 | 41 | (Forming Failed) | (Forming Failed) |
| Lifespan in a kettle (min) | 36 | 11 | 11 | 7 | 7 | — |
| Type | 2130 | 2210 | ||||
| Usage | 0.05% | 0.10% | 0.15% | 0.02% | 0.03% | 0.05% |
| Tensile strength (MPa) | 24.2 | 18.0 | 24.5 | 25.5 | 27.7 | — |
| Hardness (shore a) | 76.1 | 73.2 | 72.2 | 77.1 | 77.2 | — |
| Tensile elongation at break (%) | 355 | 341 | 354 | 352 | 393 | — |
| 300% tensile stress (MPa) | 13.3 | 11.6 | 12.4 | 13.1 | 12.2 | — |
| Demolding time (min) | 58 | 38 | 29 | 89 | 49 | (Forming failed) |
| Lifespan in a kettle (min) | 14 | 11 | 8 | 7 | 5 | — |
Parameter settings for comprehensive environmental experiments_
| Experimental parameters | Set value | Reference standard |
|---|---|---|
| UV irradiation | UVA-340 lamp, irradiation intensity 0.68 W/m2 @ 340 nm, simulating summer noon sunlight intensity | ASTM G154-2006 |
| Salt spray corrosion | Neutral salt spray (5% NaCl solution, pH 6.5–7.2, temperature 35°C), spray cycle: 4 h salt spray/4 h drying | ISO 9227 |
| Cyclic heat load | Temperature cycle: −10°C (nighttime) → 70°C (daytime), temperature rise and fall rate of 5℃/min, simulating the temperature difference between day and night | IEC60068-2-14 |
| Long-term exposure simulation | Accelerated aging cycle: 1,000 h (equivalent to approximately 1 year of outdoor exposure) | ASTM D4329 |
Comprehensive test results of accelerated aging of materials in composite environment_
| Performance index | Initial value | After accelerated aging (1,000 h) | Degradation rate (%) | Key factors |
|---|---|---|---|---|
| Tensile strength (MPa) | 28.7 | 22.1 (±0.5) | −23 | UV rays cause chain breakage and salt spray penetration |
| Tensile elongation at break (%) | 507 | 380 (±15) | −25 | The separation between hard and soft segments intensifies |
| Shore a hardness | 84.8 | 78.5 (±1.2) | −7.40 | Surface oxidation and plasticization |
| Rain erosion lifespan (h) | 31.6 | 18.2 (±0.8) | −42 | Microcrack propagation acceleration |
| Contact angle (°) | 102 | 88 (±3) | −14 | PDMS surface migration is hindered |
| TGA residual carbon rate (600℃) | 19.28% | 15.02% (±0.3) | −22 | Acceleration of Thermal Oxygen Decomposition |
| Storage modulus (−40℃, MPa) | 1,506 | 1,120 (±45) | −26 | Low temperature brittleness increases |
| Surface crack density (pcs/mm2) | 0 | 12.5 (±2.1) | — | Salt crystal expansion stress |
Comparison of mechanical and rain corrosion properties of titanium dioxide materials with different contents
| Experiment number | TiO2 content (%) | Tensile strength (MPa) | Elongation at break (%) | Hardness/shore A | Contact angle (°) | Rain erosion time (h) |
|---|---|---|---|---|---|---|
| 1 | 0 | 27.4 | 392 | 76.1 | 85.4 | 11.5 |
| 2 | 3 | 29.5 | 414 | 77.9 | 84.6 | 13.8 |
| 3 | 6 | 30.5 | 403 | 82.6 | 86.4 | 15.8 |
| 4 | 9 | 32.4 | 425 | 84.8 | 85.7 | 17.5 |
| 5 | 12 | 25.7 | 397 | 87.4 | 86.7 | 14.8 |