Gum rubbers have been found to be stronger and tougher (i.e., more resistant to crack propagation) at lower temperature since nearly seventy years ago. According to the standard and prevailing rationale this rises from a rise of energy dissipation with decreasing temperature (increasing internal viscosity). Since our recent spatial-temporal resolved polarized optical microscopic observations reveal1,2that (a) tensile strenght reflects the inherent strength and (b) toughness is proportional to inherent strength, it is clear to us that the temperature dependence of strenght and toughness has the same physical origin. Bond dissociation kinetics are slower at lower temperature, permitting greater degree of rubber strength to high critical load and tensile stress3. In this study we further examine the temperature and rate dependencies by clarifying the role of chain dynamics in various gum rubbers prepared by crosslinking of pre-polymer of high molecular weight.
*This work is supported, in part, by the Polymers program at National Science Foundation (DMR-2210184).
–
Publication:(1) Smith, T.; Gupta, C.; Fan, Z.; Brust, G. J.; Vogelsong, R.; Carr, C.; Wang, S.-Q. Toughness arising from inherent strength of polymers. Extreme Mechanics Letters 2022, 56, 101819. DOI: https://doi.org/10.1016/j.eml.2022.101819. (2) Fan, Z.; Wang, S.-Q. Resolving stress state at crack tip to elucidate nature of elastomeric fracture. Extreme Mechanics Letters 2023, 61, 101986. DOI: https://doi.org/10.1016/j.eml.2023.101986. (3) Fan, Z.; Wang, S.-Q. Investigating dependence of elastomeric fracture on temperature and rate. Rubber Chemistry and Technology 2023
