Process induced electroactive β-polymorph in PVDF: effect on dielectric and ferroelectric properties.

Area of Science:

• Materials Science
• Polymer Science
• Solid State Physics

Background:

• Poly(vinylidene fluoride) (PVDF) is a versatile polymer with significant dielectric and ferroelectric properties.
• The electroactive β-polymorph of PVDF is key to its functional applications.
• Understanding processing effects is crucial for optimizing PVDF performance.

Purpose of the Study:

• To systematically investigate the influence of various processing conditions on PVDF's dielectric and ferroelectric properties.
• To determine the effect of processing sequence on PVDF structure and properties.
• To identify optimal processing routes for enhanced PVDF performance.

Main Methods:

• Systematic study of annealing, poling, and mechanical rolling on PVDF.
• Investigation of combined processing effects and sequences.
• Phase transformation analysis using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR).
• Evaluation of dielectric properties (permittivity, loss tangent) and ferroelectric behavior (P-E and D-E loops).

Main Results:

• All processing conditions induced a phase transformation from the α- to the β-polymorph in PVDF.
• Mechanical rolling yielded the highest β-phase fraction (approx. 85%).
• Permittivity and loss tangent decreased across processed samples.
• Poled samples, initially rolled, exhibited the highest energy density.

Conclusions:

• Processing conditions critically influence the α- to β-phase transformation in PVDF.
• Mechanical rolling is highly effective in developing the electroactive β-phase.
• Processing sequence impacts the final dielectric and ferroelectric characteristics.
• Optimized processing, particularly rolling followed by poling, can maximize energy density in PVDF for advanced applications.