Mechanical properties of piezoelectric PVDF/MWCNT fibers prepared by flat/hollow cylindrical near-field electrospinning process

The existing study focused more on one-dimensional nanostructures such as nanotubes and nanofibers for various potential applications, but less on evaluation of their mechanical properties. Therefore, this study mainly concentrates on near-field electrospinning (NFES) and hollow cylindrical near-field electrospining (HCNFES) process to fabricate permanent piezoelectricity of polyvinylidene fluoride (PVDF)/multi-walled carbon nanotube (MWCNT) nanofibers. Comparing NFES and HCNFES, it can be seen that HCNFES was fabricated under high electrical field with in-situ strong mechanical stretching for possible alignment of dipoles along the longitudinal direction of PVDF nanofiber. Therefore, PVDF nanofibers fabricated using HCNFES can be of smaller diameters and higher contents of β-phase with excellent piezoelectricity. In addition, the crystallization and mechanical behaviors of PVDF nanofibers were influenced by the PVDF solution concentration and addition of MWCNT. The tensile test shows that the yield strength increases with increasing 0.03% MWCNT and 16% PVDF solution.