Spectroscopic Investigation of an Order-Disorder Transition in Random Copolymers of Vinylidene Fluoride and Tetrafluoroethylene

Raman measurements on a series of random VF2 - TFE copolymers with a broad compositional range have been obtained as a function of temperature down to 25 degrees K. Bands in the 800-850 cm-1 region whose intensities have been previously shown to be sensitive to the transition from the ordered planar form to a disordered conformation have been used to monitor the onset of this Curie transition. As noted previously from x-ray measurements, 1 when the VF2 content is between 70 and 82 mole %, transitions are observed at temperatures that increase with VF2 content. At lower concentrations to distinct Curie transition was observed even down to 25 degrees K. Possible explanations of this result will be discussed.