Crystal Structure of Natural Rubber

The crystal structure of natural rubber has been studied by many researchers including Bunn and Nyburg. However, the accepted crystal structure has not been reported. In the present study, the X-ray crystal structure analysis was carried out by using an imaging plate at −50 °C. Four molecular chains with STS̄cisS̄TScis conformation pass through a unit cell with a = 12.41 Å, b = 8.81 Å, c = 8.23 Å, β = 94.6°, and P 2 1 / a - C 2 h 5 . In the crystal lattices, two molecular chains related by the mirror symmetry statistically occupy a crystal site with the ratio 0.67:0.33.