Making hollow fibers using pressurized spinning

This study introduces the design and development of a core-sheath pressurized spinning method for producing hollow fibers on a larger scale than conventional methods. Multiple experimental designs were analyzed to determine the optimal hollow fiber structure. Polycaprolactone was used for the sheath layer, with four different core materials (empty, gas, ethanol, and oil) tested at rotational speeds of 2000, 4000, 6000, and 8000 rpm. Pressures of 0, 0.1, 0.2, and 0.3 MPa were applied bilaterally and unilaterally to the vessel's core and sheath. A high-speed camera was used to observe the jetting behavior of the polymer solutions. Optimal operating parameters for each approach were found to be: empty core (sheath: 0–0.3—core: 0 MPa, at a rotational speed of 6000–8000 rpm), gas core (sheath: 0—core: 0.1–0.3 MPa, at a rotational speed of 4000–8000 rpm), ethanol core (sheath and core: 0–0.2 MPa, at a rotational speed of 4000–8000 rpm), and oil core (sheath and core: 0–0.1 MPa, at a rotational speed of 4000–6000 rpm). Surface morphology and size distribution were analyzed via scanning electron microscopy and a computed tomography scan, which confirmed the hollow structure. This design development offers a mean production of more than 30 times higher than coaxial electrospinning, achieving rates of 74.4, 62.4, 52.8, and 33.6 g h−1 for empty, gas, ethanol, and oil cores, respectively. The results show that this new design of core-sheath pressurized spinning can be successfully applied to large-scale production of hollow fibers, opening the path for new biomedical applications.