The polyisoprene in NR can crystallize. In the monoclinic system, there are four molecular chains in the unit cell and eight chain units of isoprene. The equivalent period of the unit cell is 0.810 nm. The density of the crystal part is 1.00g/cm3, and NR can be crystallized under low temperature and pulling conditions. The temperature range of the actual NR product is -50 to 10 ° C, and the fastest temperature of crystallization is -25 ° C, NR Crystallization is sensitive to variable responsiveness, so self-reinforcing is better.