Natural rubber (NR) is a bio-sourced material and covers more than 50% of the rubber used in the tire industry. NR exhibits strain-induced crystallization (SIC), resulting in superior mechanical properties. The mechanical strength of SIC rubber is governed by not only the viscoelastic energy dissipation but also the SIC effect; thus, experimentally measured strength for SIC rubber includes the contributions of these two components. Bridgestone has developed a methodology to quantify these two components and determine the threshold conditions for the onset of the SIC effect. The effect of the micro/macrostructure for SIC-driven strength will be presented.

• Fracture mechanics of rubber
• Strain induced crystallization of poly-isoprene rubber
• Relationship between micro/macro structure and resultant mechanical strength