Enhancing the electroactive β-phase of PVDF filaments via feedstock processing

Polyvinylidene fluoride (PVDF) is a smart piezoelectric material with remarkable properties, offering vast potential for applications in areas such as energy harvesting, biomedical devices, and sensors. Among its various crystalline phases, the beta-phase is the most electroactive, characterized by high dielectric properties. Recently, PVDF has been processed using 3D printing due to the technology's ability to fabricate complex and intricate structures, along with advantages such as design flexibility, material efficiency, and rapid prototyping. While the beta-phase content in PVDF is often enhanced through additives or post-processing, limited attention has been given to the role of feedstock preparation and extrusion parameters in phase enhancement. In this study, we investigated how feedstock preparation and extrusion parameters influence the beta-phase content of PVDF, aiming to optimize its piezoelectric properties for 3D printing applications. PVDF filaments were produced using two different methods: direct extrusion from PVDF pellets and a solution-based process involving dissolution in a solvent, followed by extrusion. Phase content, structural changes, and thermal stability were assessed using x-ray diffraction (XRD), Fourier-transform infrared spectroscopy, and differential scanning calorimetry. Results show that feedstock processing conditions significantly impact the crystallinity and beta-phase concentration in PVDF filaments. Notably, solution-processed PVDF exhibited a higher beta-phase concentration compared to the pellet-based method, suggesting that this approach may enhance piezoelectric performance. This study highlights the importance of feedstock processing techniques as a means of tailoring the electroactive properties of PVDF for advanced 3D-printed applications.