Elongation is the percentage increase in original length ( strain ) of a rubber specimen as a result of tensile force ( stress ) being applied to the specimen. Elongation is inversely proportional to hardness , tensile strength , and modulus . That is, the greater a material’s hardness, tensile strength, and modulus, the less it will elongate under stress. It takes more force to stretch a hard material having high tensile strength and high modulus than to stretch a soft material with low tensile strength and low modulus.
