Quantifying Supercritical CO2 Dilation of Poly(vinylidene fluoride) and Poly(vinylidene fluoride-co-hexafluoropropylene) Utilizing a Linear Variable Differential Transducer: Plasticization and Melting Behavior


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 (Tm) of both polymers is lowered due to supercritical CO2 plasticization. For PVDF, the maximum lowering of Tm (ΔTm=23°C) occurs between 483 and 552 bar. The corresponding value for the copolymer is ΔTm = 26°C at 552 bar. At higher pressures, hydrostatic effects override plasticization and Tm increases for both polymers. By comparing Tm in N2, a noninteracting gas, the opposing effects of plasticization and hydrostatic pressure on Tm are explored.

Publication Title

Macromolecular Symposia