RHEOLOGICAL PROPERTIES OF POLY(VINYLIDENE FLUORIDE) IN MOLTEN STATE

The rheological behavior of poly(vinylidene fluoride) (PVDF) samples of different molecular weights was investigated by means of high pressure capillary rheometer and rotational rheometer. Information on the rheological properties of such materials above melt temperatures is of interest as this can lead to an improved understanding of polymer behavior in processing and fabrication technologies. Shift factors derived from time-temperature superposition showed good fit to the Arrhenius equation with a flow activation energy E of almost 74 kJ/mol, which was essentially independent of polymer molecular weight suggesting the unit of flow was a collective motion of chain segments rather than the whole chain itself.