Structural responses of electrospun PVDF fibers induced by specific stretching and ensuing heating

Abstract Microstructure of electrospun fibers is often invoked to explain their properties but that is challenging to quantify properly. The electrospun PVDF fibers being rich in the β ‐phase crystal due to excellent piezoelectric properties are promising energy‐harvesting materials for wearable and implantable applications. In this work, structural responses of electrospun PVDF fibers were investigated under the conditions of specific stretching at 25°C and ensuing heating from 25 to 170°C at strains of 5%, 10%, 20%, respectively, using the in situ WAXD with a thermos‐mechanical coupled equipment. In this process, the fiber morphology, and the crystal orientation, the crystal structure, the β ‐phase content, as well as mechanical property of elctrospun PVDF fibers were studied. It is found that the specific stretching affects the β ‐phase crystal more than ensuing heating when the heating temperature is lower than the melting temperature of the fibers. Moreover, after 20% stretching and ensuing heating to 150°C, the tensile strength of electrospun PVDF fibers membrane can rise to 12.8 MPa, which is more than three times that of the pristine fibers, which is attributed to the higher crystal orientation and β ‐phase content, along with the alignment of the fibers. Therefore, structural responses of electrospun PVDF fibers induced by specific stretching and ensuing heating are propitious to explain and tailor their properties in practical applications, which also gives potential insights into other fibers.