Spinning Mechanism And Experiment Of Nanofiber Core-spun Yarn

A jet electrospinning unit designed by ourselves was used to fabricate nanofibersbased on the principle of bubble bursts forming multiple jets. The nanofiber yieldcould be increased significantly by this method and the yield of per electrospinningunit could be up to4.3g/h. Nanofiber bundle could be obtained from a multi-nozzlejet electrospinning device, which was assembled through several electrospinning units,and the yield of nanofiber bundle could be up to3.2g/h. The effect of voltage, airflow rate and solution flow rate on nanofiber diameter and the yield of nanofiberbundle were discussed. Then two projects were proposed to prepare continuoustwisted nanofiber core-spun yarns based on above mentioned methods. Project one:Nanofibers ejected from multiple nozzles were gathered and bundled by conjugateelectrospinning and were then twisted on the surface of a core yarn through therotation of a metal funnel. The morphology, mechanical property and hydrophobicproperty of viscose filament/polyvinylidenefluoride (PVDF) nanofiber core-spunyarns were discussed. The experimental results obtained in this study showed thatPVDF nanofibers were perfectly coated on the core yarn surface with good orientationand uniform twist distribution. After coating with twisted PVDF nanofibers, themechanical properties of the yarn improved significantly compare with core yarn, andthe yarn had good hydrophobic property with a contact angle of150°. Project two:First, continuous nanofiber bundles were obtained based on the principle ofconjugated electrospinning. Then the continuous nanofiber bundles will be twisted oncore yarn surface through3D high-velocity rotational airflow. The airflow field insidethe nozzle-twisting device was simulated numerically by FLUENT software and theeffect of air pressure on the structure and mechanical property of nanofiber core-spunyarn were analyzed. The airflow forms a3D high-velocity rotational airflow after it is injected into the twisting chamber from the jet orifice, and takes on the characteristicsof a vortex flow. Under the effect of this vortex flow, the nanofibers are evenlytwisted around the core yarn and coated onto its surface, with the fibers oriented in thesame direction as the twist direction. The structure of nanofiber core-spun yarnfabricated by airflow twisting was denser and the spinning velocity was highercompare with the nanofiber core-spun yarn fabricated by multi-nozzle jetelectrospinning.