The performance of PU elastomer is between plastic and rubber. The properties of PU elastomers synthesized by different types of polyols are slightly different. Polyester PU has high mechanical properties and good oil resistance, but poor water resistance; polyether PU has better low temperature resistance and hydrolysis resistance than polyester. type, but the oil resistance and mechanical properties are slightly worse.
- Mechanical properties of PU
The hardness of PU elastomer varies widely, from Shore A10 to D80, and the elongation at break is as high as 600%~800%. The highest Shore hardness of natural rubber is A70 only, and the elongation at break is 550%.
The tear strength of PU elastomer is high, which is 2~10 times greater than that of natural rubber.
The PU elastomer has high resilience and good shock absorption effect.
PThe strain of PU elastomer lags behind the stress, so that the lost energy becomes heat; a large amount of internal heat limits the use of PU elastomer in high-speed sports, so it can only be used in low-speed occasions.
PU elastomer has good wear resistance. The specific wear resistance is as in the table below. Generally, the wear resistance is 3 to 10 times that of natural rubber; its friction coefficient varies in the range of 0.2 to 3, which is suitable for shoe sole materials.
| Abrasion resistance of different plastics | |||||
| Variety | PU elastomer | PA610 | PET Film | PA11 | HDPE |
| Abrasion/mg | 0.5~3.5 | 16 | 18 | 24 | 29 |
| Variety | PA66 | LDPE | HPVC | ABS | PS |
| Abrasion/mg | 49 | 70 | 122 | 275 | 324 |
Thermal properties of PU
PU elastomer has poor heat resistance and generally only be used below 80℃. Temperatures exceeding 80℃will lead to performance degradation. However, PU elastomer has better low temperature resistance, and polyether is the best. It can be used in the range of -70~-62℃.
- Environmental performance of PU
The water resistance of PU elastomer is average, and immersion in water or exposure to moisture will cause a decrease in mechanical properties; but the hydrolysis resistance of polyether-type PU is 5 to 10 times better than that of polyester-type.
PU elastomers have good oil resistance, resistance to non-polar and weak polar solvents, among which polyether is better than polyester. But it is not resistant to strong acid, strong alkali or polar solvent.
PU elastomer has good ozone and oxygen resistance, good UV and radiation resistance. It can be used outdoors for a long time.
PU elastomer has good physiological compatibility and good antithrombotic properties. It can be used in artificial organs in the human body.
- Electrical properties of PU
PU elastomer has good electrical properties. The greater the hardness, the better the electrical properties. However, the electrical performance of PU decreases after absorbing water, which limits the application in high insulation occasions.
