Rubber has got two three-dimensional networks: physical and chemical. Relatively weak intermolecular bonds, faint links of macromolecules with carbon black particles, and carbon black structure make a physical network. Chemical links arising under vulcanization and chemisorption bonds between molecules and carbon black particles form a chemical network. A method is developed that enables estimation of physical and chemical network density by measuring rubber elasticity modulus under small deformation. Since elasticity modulus of the chemical network decreases and that of the physical network increases as temperature lowers, it enables improvement of rubber cold-resistance by raising chemical network density. A mechanical model shows that, firstly, rubber cold-resistance should increase under increasing deformation and, secondly, deformation characteristics at room temperature enable prediction of rubber performance under low temperatures.
Kucherskii, A. M. (2000). Effect of chemical and physical crosslinks on cold-resistance of rubbers. Polymer Testing, 19(4), 445–457. https://doi.org/10.1016/S0142-9418(99)00017-3