The mechanism of α-γ transition of poly- (vinylidene fluoride) in the miscible blends

The simultaneous DSC-FTIR was used for the observation of crystallization and melting of poly(vinylidene fluoride) (PVDF) and its blends with poly(methyl methacrylate) (PMMA) and poly(ethyl methacrylate) (PEMA). The isothermal crystallization was carried out under the condition of both α-form and γ-form crystallized competitively. The crystal growth rate of α -form and γ -form were evaluated from the absorbance changes at 795 cm-1 (α -form, CH2 rocking) and 810 cm-1 (γ -form, CH2 rocking) obtained by the DSC-FTIR. The crystal growth rate of γ -form decreased at the same crystallization temperature in the order of PVDF/syn-PMMA, PVDF/PEMA and PVDF/at-PMMA, which was corresponding to the order of interaction parameter. The mechanism of α -g transition of PVDF in the miscible blends with at-PMMA, syn-PMMA and PEMA was evaluated from the relationship between the decrease of α -form and the increase of γ -form. The critical crystallization temperature, at which the transformation from α -form to γ -form proceeded only in the solid state, shifted to higher temperature side in the order of interaction parameter.