Some specific properties of Polyurethanes when examined show it to be a more practical choice as compared to those of rubber, metal and plastic.
» Abrasion Resistance:
The outstanding abrasion resistance of cast polyurethanes has resulted in thousands of successful applications. In laboratory tests as well as in field applications, cast Polyurethanes show a definite wear advantage over many other materials. In field studies, polyurethanes have outworn rubbers and plastics, as well as steel and ceramics in some applications, by a factor of 8 to 1.
The following figure illustrates a comparison of abrasion properties of Polyurethane with rubbers and plastics.
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Stress / Strain Properties:
Some plastics have high modulus and tensile strength but low elongation. Most rubbers, have high elongation but low modulus and tensile strength. Polyurethane elastomers have high modulus, high tensile strength and high elongation. This combination imparts toughness and durability to the part.
The following chart illustrates the strees/strain properties of polyurethanes as compared with rubber materials.
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Compression Properties:
Cast Polyurethanes have much higher load-bearing capacity than conventional elastomers of similar hardness.
The following figure is a comparison of the compressive stresses required to cause a 10% deflection with samples of cast polyurethanes and Neoprene rubber. This high load bearing capacity, combined with the superior abrasion and toughness is an important advantage in applications like metal forming die-pads, die springs, Fork lift tires, caster wheels, industrial rolls, etc.
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Hardness and Resilience:
Cast Polyurethane elastomers can be compounded in a wide range of hardness from 20A to 75D (soft as a rubber band or as hard as plastic) Special formulations of cast polyurethanes can be made with resilience values as low as 2% or 75%. This is ideal for applications such as springs and shock mounts.
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