Compounds can be produced over a wider stiffness range with natural rubber than with any other material. Natural rubber has a large deformability capacity. This, coupled with its ability to strain crystallize, gives it added strength while deformed. Its high resilience, which is responsible for a very low heat buildup in flexing, makes NR a prime candidate for shock and severe dynamic loads. Thus, in applications where properties such as flexure, cut resistance, abrasion resistance, and general endurance would be adversely affected by heat in less-resilient rubbers, NR is recommended because of its low heat buildup.
Natural rubber does have some shortcomings.
Degradation from such environments are essentially surface effects that can be tolerated or minimized by using thicker cross sections, by shielding, or by adding antioxidants and antiozonants. Natural rubber can often be the first choice for many high-performance applications if it can be made to survive in the service environment. It remains the best choice for tires, shock mounts and other energy absorbers, seals, isolators, couplings, bearings, springs, and dynamic applications. The synthetic rubber that is closest to duplicating the chemical composition of natural rubber is synthetic polyisoprene. It shares with natural rubber the properties of good uncured tack, high unreinforced strength, good abrasion resistance, and those characteristics that provide good performance in dynamic applications.