Investigation of Swelling Behavior of NR Vulcanisates

A relationship between swelling behavior and the Mooney-Rivlin constant (C 2), which has been suggested as being associated with intermolecular forces between cross-linked polymer chains and flexibility of the NR network structure, was observed under a constrained swelling condition of 100% elongation (by length). It was found that determination of the C 2 value can be used to estimate the degree of swelling of the NR vulcanisates under equilibrium condition when different cross-link characteristics were involved and compared. The swelling results from the use of the C 2 value were compared to those from a sorption method—the results from two methods under the equilibrium state being in good agreement. The degree of swelling of the NR vulcanisates with a similar cross-link density was examined in detail by varying cross-link type and structure. In addition, the effects of molecular size and shape of swelling solvents and the molar mass of the rubber on the degree of swelling were monitored.