Natural rubber is one of the main raw material of rubber expansion joints, generally refers to the elastic solid material collected from Brazil rubber trees. This article focus on the properties and applications of natural rubber.

Crude rubber and low crosslinking density vulcanized rubber has high elasticity. At temperature range of 0-100℃, springback ability between 50-85℃, elasticity modulus only 1/3000 of steel’s, elongation as high as 1000%, when stretch it to 350%, the retraction permanent deformation only has 15%. The elasticity of natural rubber products ranks only second to butadiene rubber among all-purpose rubber.

Natural rubber products’ crude rubber, rubber compound and vulcanized rubber has high strength. The Green Strength(tensile strength of unvulcanized rubber) of natural rubber is up to 1.4~2.5Mpa. Natural rubber also has excellent wearing resistant feature, its tearing strength as high as 98kN/m.

Natural rubber products is easy to dissolve in non-polar solvent and non-polar oil. Natural rubber products can’t dissolve in polar solvent such as acetone, ethyl alcohol and water, natural rubber is able to bear 10% hydrofluoric acid, 20% hydrochloric acid, 30% sulfuric acid and 50% sodium hydroxide.