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G. Janowska, L. Ślusarski, P. Rybiński

Thermal analysis of swollen sulfur vulcanizates of butadiene-acrylonitrile rubber

Polimery 2005, No 3, 196



Summary

The subject of investigations was butadiene-acrylonitrile rubber Perbunan NT 3945 (NBR 39) before and after crosslinking with tetramethylthiuram disulfide. The effects of crosslinking density and type of solvent (benzene, toluene, dimethylformamide) on the values of phase transitions temperatures of swollen and not swollen vulcanizates of this rubber have been investigated. It has been found, on the basis of glass transition temperature (Tg) measurements, that the retardation of segmental mobility of NBR 39 macromolecules took place at lower temperature than its starting independently on rubber crosslinking density or the type of swelling liquid. Investigations have shown the clear effect of thermodynamic affinity of the solvent used both on Tg of NBR 39 and on thermodynamic parameters (temperature, enthalpy) of the process of thermal crosslinking of elastomer after swelling liquid evaporation. On DSC curves of swollen gels there are visible effects related to crystallization and melting of the solvents present as well as the processes coming from the changes of polymer/solvent interactions or thermodesolvation. Contrary to benzene or toluene, not limiting the ability of vulcanizates to thermal crosslinking after the solvent evaporation, dimethylformamide limits this process because of its different thermodynamic interactions with NBR 39.


Key words: butadiene-acrylonitrile rubber, sulfur vulcanizates, swollen vulcanizates, interactions with swelling solvents, DSC


G. Janowska, L. Ślusarski, P. Rybiński

Thermal analysis of swollen sulfur vulcanizates of butadiene-acrylonitrile rubber