Aging of Raw Rubbers at High Temperatures

The problem of the aging of raw rubbers and cured rubbers based on them, which manifest ability to work at high temperatures (200-400°C) has attracted the attention of many scientists in recent years [26-33]. Among the large number of thermally stable polymers synthesized in laboratories, copolymers of fluoroolefins and silicone rubbers have received the greatest industrial use abroad. 

Fluorine-containing elastomers combine high thermal stability with great stability to the action of various solvents, oils, fuels, and other a ressive media. The high stability of fluororubbers is due primarily to the high energy of the C-F bond, equal to 124 kcal/mole. 

In a study of the thermal decomposition of the copolymer of tri-fluorochloroethylene with vinylidine fluoride, it was established [34] that 

TABLE 33. Values of the Activation Energy of the Accumulation of Residual Deformation of Vulcanizates of Raw Fluororubbers 

The activation energy of the splitting out of hydrogen halides from an elastomer of the type of Kel-F in the indicated temperature interval is equal to 29 kcal for HCl and 34 kcal for HF. 

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