Influence of annealing and chain defects on the melting behaviour of poly(vinylidene fluoride)

• Published in: European polymer journal 2003-08, Vol.39 (8), p.1713-1720
• Main Authors: Marega, C., Marigo, A.
• Format: Article
• Language: English
• Subjects: Annealing; Applied sciences; Chain defects; Differential scanning calorimetry; Exact sciences and technology; Melting behaviour; Organic polymers; Physicochemistry of polymers; Poly(vinylidene fluoride); Properties and characterization; Thermal and thermodynamic properties; X-ray scattering
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/S0014-3057(03)00062-4

The melting behaviour of poly(vinylidene fluoride) (PVDF) was investigated by differential scanning calorimetry (DSC) and small- and wide-angle X-ray scattering in order to study the influence of the chain defects content and of the temperature of annealing on the crystallization and melting behaviour. All the DSC scans show a double endotherm and the analysis of the data suggests that the low temperature endotherm is due to the melting of a population of thin lamellae, whose thickness increases during the annealing, but a high content of chain defects prevents the lamellar thickening and the main effect in this case is the crystallization of thin lamellae from a portion of polymer which did not crystallize during the quenching from the melt. Furthermore, the two melting endotherms, which are observed, can be partially ascribed to a melting–recrystallization process. Furthermore, stepwise isothermal cooling was performed in a differential scanning calorimeter followed by melting scans of fractionated PVDF samples to point out the possible presence of a series of endothermic peaks.