Non‐linear viscoelasticity of carbon black–fluoroether rubber mixture studied by large amplitude oscillatory shear tests

Non‐linear viscoelastic characteristics of carbon black (CB)‐filled fluoroether rubber mixture samples are investigated by large amplitude oscillatory shear (LAOS) tests. Three analysis approaches based on LAOS tests are then used to discuss correlations between rheological behavior and CB‐filling amount. Each non‐linear viscoelastic parameter of the mixture presents a three‐stage characteristic with increasing CB content, which are attributed to the alteration of CB–elastomer network structure, corresponding to the state where gum continuous phase, CB–elastomer mesophase, and excessive CB agglomerates predominate in the mixture compound, respectively. According to the findings in engineering experiments, a CB content of 35–40 phr is recommended, taking into account tensile, hardness, and aging properties. Excessive CB agglomerates are found to reinforce CB–elastomer networks at elevated temperatures. For cold‐resistance properties, structural changes in CB–elastomer network are proven to exert little effect on Tg, but a higher CB content was found to slightly enhance the cold‐resistance coefficient, probably due to the decrease in velocity fraction of gum rubber. Highlights LAOS tests were utilized to study the influences of CB on fluoroelastomer; Three‐stage alteration was observed in the mixture with increasing CB content; Correlation between CB content and the engineering properties was discussed. A three‐stage pattern in non‐linear viscoelastic behavior was observed in LAOS tests for fluoroether rubber mixture with increasing CB content, corresponding to the state where continuous phase of gum, CB–elastomer mesophase, and excessive CB agglomerates predominate in the mixture compound, respectively.