Composition heterogeneity of tetrafluoroethylene-hexafluoropropylene random copolymers characterized by successive self-nucleation and annealing
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In the present work, successive self-nucleation and annealing (SSA) was applied to a series of tetrafluoroethylene-hexafluoropropylene random copolymers (FEPs). Multiple melting peaks were observed for all FEP samples after SSA thermal treatment. The lamellar crystal thicknesses were calculated from the melting temperatures, and the mass percentages of the crystals of specific thickness were obtained from the areas of the melting peaks. As a result, distributions of the lamellar thickness, which can be correlated to the composition distribution, were determined. It was found that the composition distribution of the FEP samples tended to become more heterogeneous as the content of hexafluoropropylene (HFP) comonomer increases. Samples with the same HFP content might also have different composition distributions.
KeywordsSuccessive self-nucleation and annealing Composition distribution Tetrafluoroethylene-hexafluoropropylene random copolymer
This work was supported by the National Basic Research Program of China (973 Program) (2011CB606005) and the National Natural Science Foundation of China (51073138).
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