COMPOSITIONAL VARIATION OF THE GLASS-TRANSITION AND THE ASSOCIATED DIELECTRIC-RELAXATION IN COPOLYMERS OF VINYLIDENE FLUORIDE AND TRIFLUOROETHYLENE

The glass transition temperature (T-g) of a series of statistical copo lymers of vinylidene fluoride and trifluoroethylene has been determine d experimentally. Its variation as a function of the chemical composit ion of the copolymers has been discussed based on the Fox, Di Marzio a nd Couchman equations. Using T-g = -42 degrees C for poly(vinylidene f luoride) and a value of T-g usually reported for polytrifluoroethylene (T-g = 31 degrees C), a significant discrepancy has been obtained bet ween experimental and predicted values. Thus, it has been suggested th at the glass transition temperature for polytrifluoroethylene is locat ed in the range of -20 to -10 degrees C, which is consistent with Wund erlich's thermal analysis data.