（1） Mechanical properties: the mechanical properties of TPU elastomers mainly include hardness, tensile strength, compression performance, tear strength, resilience and wear resistance, bending and disturbance resistance, etc. in addition to these properties, TPU elastic plastics have higher shear strength and impact work.

(a) Hardness: hardness is an index of the ability of materials to resist deformation, nicks and scratches. The hardness of TPU is usually measured by shore A and shore D (Shore D, usually refers to materials with higher hardness). Shaola is used for soft TPU and shore D is used for harder TPU. The hardness is mainly determined by the hard segment content in TPU structure. The higher the hard segment content, the higher the hardness of TPU will rise. The other properties of TPU will change after hardness rise, tensile modulus and tear strength increase, rigidity and compression stress (load capacity) increase, elongation decrease, density and dynamic heat generation increase, and environmental resistance increase. The hardness of TPU has a certain relationship with temperature. The hardness of TPU suddenly increases and becomes hard and inelastic at the temperature of sudden change, which is due to the crystallization of soft segment.

(b) The relationship between hardness and elongation and tensile stress and tear strength. With the increase of TPU hardness, 100% and 300% of the constant elongation stress increased rapidly, and the elongation decreased. This is mainly due to the increase of hard segment content: the higher the hard segment content, the more likely the hard segment phase to form a sub crystal or the increase of the number of physical crosslinking, the deformation of the material is limited. If the deformation of the material is made, the stress must be increased, so that the fixed elongation stress is increased and the elongation decreases. The relationship between TPU hardness and tear strength increases rapidly with the increase of hardness, and the reason is the same as the explanation of modulus.

(c) TPU hardness (Shore hardness 55a-98a ± 2a), as low as 55-70a, can be used in the strap, elastic belt and other products with high elastic hand feeling requirements; the hardness is up to 70d-85d, and can be used in shoe material skin, etc. The hardness of the application range is about 85a-95a, which can be used for injection molding mobile phone accessories, automobile accessories, casters, extrusion wires and cables, pipes, profiles, etc. (Note: the hardness flat tubes of materials used in our extrusion products are 80a-90a; round pipes are 80a-98a).

(d) How does TPU's hardness unit a convert to d:d = A-50 (or 40).

（2） Raw material technology

（3） Properties (physical and environmental)

1. Wear resistance

When the material is often subjected to friction, scraping, research and falling, it will cause gradual wear of its surface, so the choice of wear is very important. TPU plastic material has excellent wear resistance, more than five times more than natural rubber, and is one of the materials of wear-resistant products.

2. Tensile properties (elasticity)

The tensile strength is up to 70MPa, and the elongation at break can be as high as 400% - 1000%. The lower the hardness, the higher the elongation at break, the lower the hardness.

3. Tear performance

The rupture of elastomer is called tearing because of the crack expansion. Tear strength is the ability of material to resist tearing. Generally speaking, TPU has high tear resistance, and tear strength is very excellent compared with some rubber plastic glue.

4. Flexion performance

Many plastic materials are prone to fracture under repeated cyclic stress. TPU products can maintain excellent bending resistance under different environments, which is one of the best choice for polymer materials.

5. Hydrolysis resistance

TPU has good water resistance under turbidity, and will not hydrolyze obviously in 1-2 years, especially polyether series. Polyester series is completely decomposed after soaking in 50 ℃ water for half a year or 70 ℃ for 3 weeks or 100 ℃ for 3-4 days. This is one of the reasons why TPU is suitable for environmental protection. If it is necessary to contact with water frequently, it is recommended to use polyether series. TPU tubes with medical and food functions also use polyether series.

6. High temperature resistance and anti oxidant performance

The general plastic raw materials are easy to oxidize in the environment of over 70 ℃ for a long time, and TPU has good antioxidant capacity; generally speaking, TPU has a temperature resistance of 120 ℃ (Note: 120 ℃ is a special material, which needs to be customized; the conventional materials are 40-70 degrees below zero).

7. Oil resistance and drug resistance

TPU is a kind of high polymer material with strong polarity, and its affinity with non-polar mineral oil is very small, and it is almost free from erosion in fuel oil (such as kerosene, gasoline) and mechanical oil (such as hydraulic oil, oil, lubricating oil, etc.); among them, polyester series products have better oil resistance; TPU film and sheet material have little volume change for oil, and tensile strength is even higher than original value; It is important to note that if there is a small amount of water in mineral oil, it will have a negative effect on the physical properties of the film to varying degrees.

8. Low temperature performance

TPU has very good low temperature resistance, usually up to - 50 ℃, which can replace all fields that PVC cannot be used because of low temperature embrittlement, especially suitable for cold belt related products.

9. Air tightness

TPU is easy to use high cycle wave or hot pressing to weld, so it is widely used in inflatable products. Gas coefficient refers to the rate of gas passing through the specified area of the sample at a certain temperature and pressure. The permeability of the same material to different gases sometimes varies greatly. Generally speaking, the air tightness of polyester series products is better than that of polyether series (our products are produced with polyether materials).

10. Biomedical properties

TPU has excellent biocompatibility, non-toxic, non allergic reaction, no local irritation, no heat source, so it is widely used in medical, health and other related products, sports and protection equipment.