Polyurethane catalyst elastomers have been widely used in military, aerospace, acoustics, biology and other fields. The following will introduce their main properties:
1、 Hardness
The hardness range of ordinary rubber is from Shao A20 to Shao A90, the hardness range of plastic is about Shao A95 to Shao D100, while the hardness range of polyurethane elastomers is as low as Shao A10 and as high as Shao D80, and does not require the help of fillers. What is particularly valuable is that elastomers still have good rubber elasticity and elongation under plastic hardness, while ordinary rubber can only achieve higher hardness by adding a large amount of fillers and significantly reducing elasticity and elongation as a cost.
2、 Mechanical strength
Polyurethane elastomers have high mechanical strength, manifested in Young's modulus, tear strength, and load-bearing capacity.
3、 Wear resistance performance
The wear resistance of polyurethane elastomers is very outstanding, and the test results are generally in the range of 0.03-0.20mm3/m, which is about 3-5 times that of natural rubber. In practical use, the effect is often better due to factors such as lubricants. The wear resistance is closely related to the tear strength and surface condition of the material. The tear strength of polyurethane elastomer is much higher than other rubbers, but its friction coefficient is not low, generally above 0.5. This requires attention to adding oil lubricants or a small amount of molybdenum disulfide or graphite, silicone oil, tetrafluoroethylene powder, etc. in actual use to reduce the friction coefficient and minimize frictional heat generation.
4、 Oil and drug resistance performance
Polyester polyurethane elastomer is a highly polar polymer material. The affinity with non-polar mineral oil is low, and it is almost not corroded in fuel oil and mechanical oil, much better than general rubber and comparable to nitrile rubber. However, it swells greatly in alcohols, esters, ketones, and aromatic hydrocarbons and gradually destroys at high temperatures. Swelling is significant in halogenated hydrocarbons, and sometimes degradation occurs. If polyurethane elastomer is immersed in an inorganic solution without the action of polyurethane catalyst, it is similar to immersion in water. Degradation is faster in weak acid and weak alkali solutions than in water, and strong acid and strong alkali have a greater corrosive effect on polyurethane.
The use temperature of polyurethane catalyst elastomer in oil is below 110 ℃, which is higher than the use temperature in air. However, in multiple engineering applications, oil is always contaminated by water. Experiments have shown that as long as the oil contains 0.02% water, almost all of the water can be transferred to the elastomer, and at this point, there will be a significant difference in the effectiveness of use.
