Thermal analysis applied to studying the influence of ionic liquids on the vulcanization, thermal stability and damping properties of ethylene-propylene-diene rubber

The main aspect of the research was developing new systems for activating sulfur vulcanization of ethylene-propylene-diene elastomer (EPDM) with greater activity than the micrometer zinc oxide that is traditionally used. Differential scanning calorimetry (DSC) was applied to study the temperature and enthalpy of EPDM vulcanization. The range of vulcanization temperatures and the enthalpy of this process were determined. Thermogravimetric analysis was performed to characterize the effect of ILs on the thermal stability of vulcanizates. Dynamic mechanical analysis with tension deformation was used to study the influence of ILs on the loss factor (tan δ) of EPDM determined as a function of temperature, which is a measure of the ability of the material to dampen vibration. DSC results indicated that ILs significantly reduced the onset temperature and enthalpy of EPDM vulcanization. The most active were alkylimidazolium chlorides, which eliminated the post-curing process. Owing to lower decomposition temperature compared to EPDM, ILs decreased the thermal stability of vulcanizates. On the other hand, ILs had no significant influence on damping properties of EPDM in the rubbery elastic region. Vulcanizates containing ILs exhibited stable dynamic properties at the temperatures of use.