On the development of PVDF-La doped ZnO composites-based strands for sensing applications

Abstract

Over the last 2 decades, significant studies have been reported on polyvinylidene fluoride (PVDF) composites for sensing applications. However, little has been reported on using lanthanum (La)-doped ZnO reinforced in PVDF for enhanced sensing capabilities. This study reports the development of PVDF-based composite filaments/strands with nanoparticle (NPs) reinforcement of ZnO and 1%(La)-doped ZnO for advanced sensing purposes. PVDF composites at different filler loadings (1–5 by wt%) were prepared utilizing melt extrusion. The melt flow index (MFI), piezoelectric coefficient (D₃₃), dielectric constant (ε_r), loss tangent (tan δ), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and mechanical studies were carried out on the prepared PVDF composites. The results suggest that the MFI increased with reinforcement (highest ≈ 13.3 g/10 min for PVDF–5% La-doped ZnO). FTIR spectra confirm a higher formation of β-phase, more significant in La-doped PVDF composites, indicating a higher degree of electroactive alignment. SEM data showed that La-doped ZnO composites had a more homogeneous grain size and lower porosity (∼42%) compared to virgin PVDF (∼49%) and PVDF–ZnO (∼58%). The TGA showed PVDF–4%–La–doped ZnO to be more thermally stable (residue: 31.7%) than virgin PVDF (28.9%). Mechanical testing revealed that PVDF-3%La-doped ZnO contained the highest peak strength (38.7 MPa) and elastic modulus (1960.7 MPa), suggesting good interfacial bonding. The electrical characterization exhibited an enhanced voltage (5 V) and resistance (175 Ω) in the La-doped ZnO composites, suggesting promising piezoelectric sensing capabilities. The results indicated that La doping on ZnO improved the dielectric, mechanical, and thermal properties of PVDF for flexible electronics and human-machine interface applications.