The effect of salt on poly (vinylidene fluoride) polymorphs formation

• Main Author: Tan, Li Yi.
• Other Authors: Ng Hsiao Yen
• Format: Final Year Project
• Language: English
• Published: 2011
• Subjects: DRNTU::Engineering::Materials::Organic/Polymer electronics
• Online Access: http://hdl.handle.net/10356/44039
• Institution: Nanyang Technological University

Poly (vinylidene fluoride), PVDF, had been extensively studied due to their remarkable piezoelectricity, chemical resistance, good thermal stability and high dielectric strength. These properties provide a wide range of applications such as biotechnology, transducer materials, capacitor dielectrics and also for biomedical sectors. In addition, its piezoelectricity may also stimulate and retard cellular growth, thus a potential biomaterial. The main objective of this report is to investigate the effects of different salts on the characteristic of PVDF films made through solvent casting. Mono- and di-valent salt of the same anion (Cl-) were selected; NaCl, KCl, MgCl2 and CaCl2. PVDF films, filled with mass fractions (wt ≤ 5%) of salts, were characterized by Fourier Transform Infrared (FTIR) Spectroscopy, Differential Scanning Calorimeter (DSC), Scanning Electron Microscope (SEM) and Thermogravimetric Analysis (TGA) for its structural, morphology and thermal properties. It was revealed that fraction of β- phase increased significantly with the addition of salt and this was strongly affected by the ions size of the cations from the salt. This was because cation size and valency interaction play a direct role in the ion-dipole interactions between the polymer and solvent. Thus, it was concluded that smaller cations would induce larger fraction of β-phase in PVDF.