INVESTIGATION OF CONDENSATION TYPE ELASTOMERS

The ultimate goal of the exploratory investigations described is the development of a rubber for special Air rce applications. High thermal stability 350 F or higher resistance to aromatic fuels, synthetic ester base oils and hydraulic fluids resistance to ozone and to weathering oxidation effects resistance to acids, bases, and salts resistance to abrasion and satisfactory performance at -65 F or lower are major requirements for such an elastomer. Preliminary compounding and testing attudies with an elastomer based on a fluorine containing polyester, made from adipyl chloride and 2,2,3,3,4,4-hexafluoropentanediol, have given promising results. At the present stage of development, compounded and crosslinked specimens of huafluoropentylene adipat. retain useful mechanical properties after aging in air at 400 F 70 and 168 hour tests, and in diester oil at 350 F 70 hour test are resistant to paraffinic and aromatic fuels and exhibit a brittle temperature of -98 F ASTM D-746. This report describes the preparation, compounding, cross-linking and properties of hexafluoropentylene adipate elastomer as well as syntheses and properties of other fluorine containing condensation polymers and difunctional starting materials. Data indicating that increasing fluorine content of the polymers decreases their solubility in common solvents without regard to position of the fluorine in the polymer are extended. On the other hand, these data show that position of the fluorine, rather than total fluorine content of the polymer is of most importance in affecting brittle temperatures.