Mechanical properties of polyurethane

Polyurethane elastomer has good mechanical properties, such as good young's modulus, tensile strength, tear strength and load capacity.

Young's modulus and tensile strength

Within the elastic limit, the ratio of tensile stress to deformation is called Young's modulus (E) or elastic modulus. For example, if vulcollan30 has a hardness of shore d42 and a tensile stress of 2.25mpa at 2.5% elongation, its young's modulus is: polyurethane elastomer, like other elastomers, only follows Hooke's theorem at low elongation. But its young's modulus is much higher than other elastomers. Taking the Vulkollan polyurethane elastomer series developed by Bayer company in Germany as an example, for the material with hardness of 65A, the elongation at break under the elastic limit is about 5%, and the young's modulus is about 5MPa. For materials with a hardness of 70D, the above data are 2% and 600MPa respectively. The tensile strength of polyurethane elastomer is as high as 70MPa, which cannot be compared with rubber plastics. However, the reason of permanent deformation is that the tensile strength exceeds the elastic limit, especially the dynamic load.

Polyurethane elastomers should not be used when the elongation is higher than 25%.

Tensile strength

The tear strength of polyurethane elastomer is very high, which is more than twice that of natural rubber

Loading capacity

Although the compressive strength of polyurethane elastomer is not high and the bearing capacity is not large under low hardness, polyurethane elastomer can improve the hardness under the premise of maintaining rubber elasticity, so as to achieve high bearing capacity. Moreover, the compressive stress of polyurethane elastomer increases faster than that of SBR and Cr with the increase of compression ratio.