Effects of process parameters on the properties of wet-spun solid PVDF fibers

A PVDF polymer has very good strength, toughness and piezoelectric properties and is nowadays used as the film in strain sensors, mechanical actuators, energy harvesters and artificial muscles. Furthermore, PVDF polymer is used as the fiber in hollow fiber membranes for filtration applications. This article introduces the manufacturing of solid PVDF fibers by a wet spinning process and investigates the effects of the process parameters (i.e. drawing temperatures and drawing ratios on the first and second bath) on macroscopic properties (i.e. fiber linear density, fiber shape, density, porosity, strength and elongation) of solid wet-spun PVDF fibers. Increasing the drawing ratio at the first region of the wet spinning of the PVDF fiber increases the porosity. However, if the drawing is performed at the second drawing bath, the porosity of the PVDF fibers remains almost same. The slopes of the strength vs. drawing ratio and elongation vs. drawing ratio curves increase if the drawing is performed at the second drawing bath. The drawing ratio at the first bath does not affect the tensile properties of fibers, such as tensile strength and elongation. Information about the relationships between the process parameters and macro properties of PVDF fibers is very important so that PVDF fibers with the required properties can be produced with a wet spinning process by setting the correct process parameters.