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Influence of hydrogen bonding on the viscoelastic properties of thermoreversible networks: analysis of the local complex dynamics

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Abstract The viscoelastic properties of thermoreversible polybutadiene networks in which junctions are formed by binary contacts between polar stickers (phenylurazole) are investigated by a dynamic mechanical spectroscopy within the frequency range 0.0079–79.5 Hz (0.05–500 rads−1). Time-temperature superposition is applicable in the terminal flow region and the glass transition regime, whereas thermorheologically complex behaviour is observed within the rubbery plateau region. For the terminal relaxation zone the polar stickers enhance the relaxation time and broaden the relaxation time spectrum. The thermorheologically complex behaviour within the rubbery plateau region results from the occurrence of an additional relaxation process which is attributed to the process of complexation/decomplexation of the reversible hydrogen bond contacts. The characteristic relaxation time of this process at 233 K is 0.044s. This process can also be monitored in dielectric relaxation. Discrepancies between dynamic mechanical and dielectric data are discussed.