Various implementations include a filament that includes three lobes that extend from a central portion of the filament, and the central portion defines an axial void. Each lobe bulges outwardly at its proximal end adjacent the central portion and has edges that form a continuous concave curve toward its distal end relative to an axis A-A that extends through the distal end of the respective lobe and the central portion of the filament. Thus, a width of each lobe at the proximal end thereof is greater than a width of each lobe at or adjacent the distal end, and adjacent edges of adjacent lobes intersect each other at concave proximal ends of the adjacent edges.

The present invention provides a method for successively introducing water soluble fibers into finish fibers (e.g. cotton) to produce a hollow and ultra soft structure, by introducing water soluble slivers into the center of a multi-hole feeder with multiple cotton fiber slivers arranged around the water soluble fiber in a pre-drawing process via a multi-hole sliver feeder. A plurality of these fibers can be drawn together to produces a fiber having multiple water soluble fibers. A cloth, e.g., towel, can be made using the method.

A method of forming carbon fibers having internal cavities. The method includes applying a polymer material to a tooling component to form carbon fiber precursor hollow tubes, oxidizing the carbon fiber precursor hollow tubes, and carbonizing the carbon fiber hollow tubes to form carbon fibers, each having a hollow inner cavity

The disclosure provides a method for preparing a hollow fiber membrane by melt spinning-stretching and selective swelling, including: preparing a nascent hollow fiber by melt spinning in an inert gas protective atmosphere by using an amphiphilic block copolymer as a film forming material, and stretching the nascent hollow fiber in the cooling process, a stretch rate being controlled at 200-540 mm/min, and a stretch ratio being controlled at 150-600%; immersing the obtained hollow fiber in a swelling solvent, and treating the hollow fiber in a water bath at 65° C. for 1 h; and then transferring the hollow fiber into a long-chain alkane solvent, treating the hollow fiber at the same temperature for 1-12 h, and after the completion of the treatment, immediately taking out the hollow fiber and drying the hollow fiber to obtain the hollow fiber membrane with a bicontinuous porous structure. By combining the melt spinning-stretching and the selective swelling, the method of the disclosure can synchronously and continuously improve the permeability and selectivity of the hollow fiber membrane. The treatment in the long-chain alkane solvent can make the polar chain excessively enriched on the surface of the membrane migrate inward, thereby improving the performance of the hollow fiber membrane.

A method for manufacturing a hollow fiber membrane has a spinning step of applying a first membrane forming stock solution and a second membrane forming stock solution for forming a porous membrane layer to the outer peripheral surface of a hollow porous base material using a nozzle for hollow fiber membrane spinning and solidifying these membrane forming stock solutions, wherein a draft ratio (V.sub.B/V.sub.A), which is the ratio of feed velocity V.sub.B for hollow porous base material fed out from a base material feed opening to linear velocity V.sub.A for the first membrane forming stock solution and the second membrane forming stock solution discharged from a membrane forming stock solution discharge opening of the nozzle for hollow fiber membrane spinning, is set to 1-6.

A method for manufacturing a hollow fiber membrane has a spinning step of applying a first membrane forming stock solution and a second membrane forming stock solution for forming a porous membrane layer to the outer peripheral surface of a hollow porous base material using a nozzle for hollow fiber membrane spinning and solidifying these membrane forming stock solutions, wherein a draft ratio (V.sub.B/V.sub.A), which is the ratio of feed velocity V.sub.B for hollow porous base material fed out from a base material feed opening to linear velocity V.sub.A for the first membrane forming stock solution and the second membrane forming stock solution discharged from a membrane forming stock solution discharge opening of the nozzle for hollow fiber membrane spinning, is set to 1-6.

Systems and methods can be used to produce fibers with external corrugations, internal corrugations, or both. These fibers can be used, for example, in hollow fiber membrane modules.

Systems and methods can be used to produce fibers with external corrugations, internal corrugations, or both. These fibers can be used, for example, in hollow fiber membrane modules.

Methods for the preparation of carbon fiber from polyolefin fiber precursor, wherein the polyolefin fiber precursor is partially sulfonated and then carbonized to produce carbon fiber. Methods for producing hollow carbon fibers, wherein the hollow core is circular- or complex-shaped, are also described. Methods for producing carbon fibers possessing a circular- or complex-shaped outer surface, which may be solid or hollow, are also described.

Methods for the preparation of carbon fiber from polyolefin fiber precursor, wherein the polyolefin fiber precursor is partially sulfonated and then carbonized to produce carbon fiber. Methods for producing hollow carbon fibers, wherein the hollow core is circular- or complex-shaped, are also described. Methods for producing carbon fibers possessing a circular- or complex-shaped outer surface, which may be solid or hollow, are also described.