Quantifying supercritical CO2 dilation of poly(vinylidene fluoride) and poly(vinylidene fluoride-co-hexafluoro-propylene) utilizing a linear variable differential transducer: Plasticization and melting behavior

摘要

Melting behavior of semicrystalline poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride-co-hexafluoropropylene) is investigated as a function of supercritical CO2 pressure using a Linear Variable Displacement Transformer (LVDT). The melting temperature (T-m) of both polymers is lowered due to supercritical CO2 plasticization. For PVDF, the maximum lowering of T-m (DeltaT(m)=23degreesC) occurs between 483 and 552 bar. The corresponding value for the copolymer is DeltaT(m) = 26degreesC at 552 bar. At higher pressures, hydrostatic effects override plasticization and T-m increases for both polymers. By comparing T-m in N-2, a noninteracting gas, the opposing effects of plasticization and hydrostatic pressure on T-m are explored. [References: 31]