The monomer reactivity ratio (mrr) of emulsion copolymerization of tetrafluoroethene (TFE) with vinylidene fluoride (VDF) was examined and studied at relatively low pressure.In this study with the general pressure less than 1.53MPa

Henry's law was applied well to relate the monomer concentration in the liquid phase and the mole fraction in the gas phase.In this case

the copolymer composition equation could be kept in the same way as Mayo-Lewis equation after replacing the monomer concentration with gaseous mole fraction and the mrr with apparent mrr.The initial and the end monomer mole fractions were determined with gas chromatograph (GC) and the copolymer compositions were calculated from GC experimental data as well as from the data measured by using 19F-NMR.The apparent monmer reactivity ratio estimated from reactivity ratio error-in variables model (RREVM) are 0.35 (γVDF)and 0.63(γVDF)for TFE and VDF respectively.95% probability contour shows the experiment results of apparent mrr is accurate and the compositions of such copolymers (FTFE)calculated from the copolymer composition equation produced are in good agreement with those measured by means of 19F-NMR.