Abstract
Natural rubber has a great tensile property, the very high tensile strength in particular, without the addition of carbon blacks, which has been understood to result from the stain-induced crystallization. However, there has been much discussion and confusion about the sudden stress increase at a large extension, i.e." the upturn" in NR.That is, one explains the phenomenon from the viewpoint of the reinforcement of rubber by crystals (but without any detailed discussion) and the other depicts with the non-Gaussian stress-strain relation, ignoring the strain-induced crystallization. Here, we focus on the strain-induced crystallization and the cross-linked structures of NR and search the hints to link the strain-induced crystallization to the self-reinforcement in NR.

Keywords:
Natural rubber, Strain-induced crystallization, The upturn, Cross-linked structures, Self-reinforcement

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