Quantifying the Crystalline Polymorphism in PVDF: Comparative Criteria Using DSC, WAXS, FT-IR, and Raman Spectroscopy
Sreelakshmi Moozhiyil Purushothaman, Maïté Fernandes Tronco, Marc Ponçot, Chitralekha C.S, Nathanaël Guigo, Marc Malfois, Nandakumar Kalarikkal, Sabu Thomas, Isabelle Royaud, Didier Rouxel
Abstract
Polyvinylidene fluoride (PVDF) is a semicrystalline polymer widely used in various fields, from energy harvesting to medicine. Thanks to its crystalline polymorphism, it possesses distinct properties depending on its microstructure developed during manufacturing. There is thus significant interest in quantifying the individual fractions of each α, β, and γ polymorph. This study establishes criteria for their comprehensive analysis by studying PVDF in its molten state and extending the results to analyze samples with significant variations in crystalline phases. Differential scanning calorimetry, wide-angle X-ray scattering, Fourier transform-infrared spectroscopy, and Raman spectroscopy were employed for a thorough analysis of the samples. A robust methodology involving curve deconvolution quantifies the total crystallinity ratio and fractions of the crystalline phases. This approach elucidates the amorphous contribution and considers all crystalline bands in a chosen representative region, details that have not yet been well highlighted in the literature. Comparison between the techniques ensures the reliability of the method to quantify PVDF’s crystalline polymorphs.