Perfluoroelastomers characterized by low molecular weight and freedom form color-forming impurities can be prepared by pyrolysis techniques, and are useful in pellicle coatings and other optical applications.

A process for preparing perfluoroelastomer compositions which comprise perfluoroelastomers having a plurality of nitrile groups and a plurality of carboxyl-containing groups, carboxylate-containing groups, carboxamide groups, or mixtures thereof is provided. Such compositions cure rapidly in the presence of organotin compounds.

Perfluoroelastomer compositions having high loadings of large-particle size carbon black exhibit superior performance at very high temperature.

Iodoperfluoroalkylnitriles are useful as chain transfer agents in the free radical polymerization of vinyl monomers to form perfluoropolymers. These nitrites provide end groups, which may take part in a cross-linking reaction, if desired, and also have a relatively low toxicity. The resulting perfluoropolymers are useful as molding resins and elastomers, particularly for parts where good chemical resistance and/or high temperature resistance are desirable.

This invention concerns a process for fluorinating a perfluoroelastomer which has previously been crosslinked by exposure to ionizing radiation. The resulting product has reduced outgassing. This makes perfluoroelastomer parts that have undergone the process particularly useful in clean rooms and for semiconductor manufacturing.