Britannica Sources used in this answer

How does stretching strengthen natural rubber?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Know how researchers created a synthetic material, elastomers, that can change color and texture to specific voltage change, like that of cephalopods — elastomer Learn about elastomers that are changeable in colour and texture, much like the skin of octopuses and other cephalopods. In the elastomers, these changes take place under electrical stimulation.

Natural rubber, which consists primarily of the cis-1,4 polyisoprene polymer, is considered a self-reinforcing material because of its unique behavior when subjected to mechanical force.1

Under normal conditions, the long-chain molecules of natural rubber exist in an irregularly coiled, disordered state. When the material is stretched, these polymer chains straighten out in the direction of the applied force. As they are pulled, the chains readily undergo crystallization. This stress-induced crystallization creates ordered regions within the material, which significantly increases its toughness and strength.21

Because of this ability to crystallize upon stretching, natural rubber can be extended repeatedly to seven or eight times its original length without failing, making it highly resilient for applications such as tires, springs, and mountings.1