Rheological behavior of PES/PVP/DMAc solution and PVP structural regulation for hollow fiber membrane

Abstract

Rheological study plays a significant role in hollow fiber membrane spinning process and membrane structure regulation. In this work, the rheological behaviors of polyethersulfone (PES) spinning solutions added the polyvinylpyrrolidone (grade of PVP‐K30, PVP‐K60, and PVP‐K90) were systematically investigated by rotational rheometry to understand how the PES membrane structure changes. Results show that PVP of variable molecular weights change the rheological properties of PES spinning solution, such as the viscosity (ηa), non‐Newtonian index (n), flow activation energy (Eη), structural viscosity index (∆η), storage modulus (G′), and loss modulus (G′′). The mixture with PVP‐K30 exhibits optimal spinnability but the finger‐like membrane structure is undesirable for the hemodialysis. The rheological behaviors of PES/PVP‐K60 and PES/PVP‐K90 reveal that increasing shear rate and temperature are effective ways to improve the spinnability of the mixture and the membrane structure is regulated. Meanwhile, the addition of PVP‐K60 or PVP‐K90 at their critical concentration to the PES solution can fabricate a hollow membrane with a sponge‐like structure. Combining spinnability and membrane structure, PVP‐K90 is a suitable additive for the hemodialysis membrane.

Large-Scale Fabrication of Highly Filled Polymer Fibers for Radiation Protection Safety and Wear Comfort of Multilayer Fabrics in Complex Radiations

“…This is because PMA gives additional carboxyl groups on the surface of BC particles to form rich hydrogen bonds with the hydroxyl groups of PVA, which promotes the interface interaction between BC particles and PVA . Furthermore, the viscosity of spinning solutions gradually decreases with increasing shear rate, which indicates that the spinning solutions are typical non-Newtonian fluids. , The structural viscosity index of the fluid usually is Δη > 0 in the non-Newtonian region, which can be calculated with eq , where Δη, η α , and γ̇ represent the structural viscosity index, apparent viscosity, and shear rate, respectively . The 30 wt % BC@PMA/PVA spinning solution displays Δη = 2.55, while the 30 wt % BC/PVA spinning solution Δη = 3.53.…”

“…41,42 The structural viscosity index of the fluid usually is Δη > 0 in the non-Newtonian region, which can be calculated with eq 1, where Δη, η α , and γ̇represent the structural viscosity index, apparent viscosity, and shear rate, respectively. 43 The 30 wt % BC@PMA/PVA spinning solution displays Δη = 2.55, while the 30 wt % BC/PVA spinning solution Δη = 3.53. It is believed that the higher viscosity index usually causes the worse spinnability of the spinning solution.…”

Effect of Ultrasound and Salt on Structural and Physical Properties of Sodium Alginate/Soy Protein Isolates Composite Fiber

“…indicates a low structurization but better spinnability and fiber quality [30][31][32][33][34]. In Table 1, the △η of sample CK was much higher than sample UCK which implies that the ultrasound treatment causes a low structurization and better spinnability of the fiber.…”

“…In order to further characterize the spinnability of the spinning solution Figure 3C,F. The structural viscosity index ( η) was calculated through Equation ( 3), and it can be used to characterize the structurization of a spinning solution, where a small η indicates a low structurization but better spinnability and fiber quality [30][31][32][33][34]. In Table 1, the η of sample CK was much higher than sample UCK which implies that the ultrasound treatment causes a low structurization and better spinnability of the fiber.…”

Improved Protein Removal Performance of PES Hollow-Fiber Ultrafiltration Membrane with Sponge-like Structure

“…At a PVP-k30 content of 20%, the cross-section SEM picture (Figure 4(D2)) shows a completely sponge-like structure. This is due to the increased viscosity of the spinning dope at higher concentrations, leading to slower phase separation and the presence of fewer finger-like pores in the cross-sectional structure [35].…”