1-Butene, 4-bromo-3,3,4,4-tetrafluoro-, polymer with 1,1-difluoroethene, 1,1,2,3,3,3-hexafluoro-1-propene and tetrafluoroethene 4-Bromo-3,3,4,4-tetrafluoro-1-butene, 1,1-difluoroethylene, tetrafluoroethylene, hexafluoropropene polymer 74398-72-4