Synchrotron X-ray scattering¹ tensile strength and strain-induced crystallization in carbon black filled natural rubber

The tensile strength of rubber depends on a combination of contributions, in particular on the finite extensibility of chain segments between network points and on strain-induced crystallization. In order to achieve high tensile strength at high strain at break, we optimized the composition and processing parameters to gain high molecular flexibility by the cure conditions, to acquire high flexibility of sulfur bridges by the accelerator, and to increase the modulus level without losing rubber molecule flexibility by carbon black. As a result, our formula performed a tensile strength of 42.5 MPa at 25°C under ISO-37, as officially measured by the Society of Rubber Industry, Japan, in 2004.