摘要:
A method for preparing a homogeneous braid-reinforced (HMR) PPTA hollow fiber membrane combines PPTA hollow tubular braids with PPTA surface separation layer. The method includes following steps of: (1) preparing the PPTA hollow tubular braids, wherein the PPTA hollow tubular braids which are made from PPTA filament yarns are woven by a two-dimensional braided method, the outer diameter of the PPTA tubular braids is 1-2mm; (2) preparing the PPTA casting solution as the surface separation layer, wherein the 1-3wt% PPTA resin, 0-2wt% inorganic particles and 10-20wt% pore-forming agents are mixed into 75-89% inorganic acid solvent, stirred for 1-3 hours at 70°C-90°C to form homogeneous and transparent casting solution; and (3) preparing reinforced PPTA hollow fiber membrane, wherein the casting solution as the surface separation layer is evenly coated on the surfaces of the PPTA hollow tubular braids through spinneret, and they are immersed in a coagulation bath for solidified formation.
摘要:
A porous membrane constructed of a cast polymeric film with a face located adjacent to at least a portion of the surface of a nanofiber substrate fabric. The membrane is not formed by lamination of two independent layers one layer being the film and the other being the substrate fabric.
摘要:
Described is a method for producing covalently and/or ionically cross-linked blend membranes from a halomethylated polymer, a polymer comprising tertiary N-basic groups, preferably polybenzimidazole, and, optionally, a polymer comprising cation exchanger groups such as sulfonic acid groups or phosphonic acid groups. The membranes can be tailor-made in respect of the properties thereof and are suitable, for example, for use as cation exchanger membranes or anion exchanger membranes in low-temperature fuel cells or low-temperature electrolysis or in redox flow batteries, or - when doped with proton conductors such as phosphoric acid or phosphonic acid - for use in medium-temperature fuel cells or medium-temperature electrolysis.
摘要:
A hollow fiber membrane is made by covering a tubular supporting structure with a membrane dope, converting the membrane dope into a solid porous membrane wall and dissolving the porous tubular structure. Optionally, a textile reinforcing structure in the form of a circular knit may be added around the supporting structure before it is covered in dope. The reinforcing structure thereby becomes embedded in the membrane wall. The supporting structure may be soluble in a non-solvent of the membrane wall, for example water, and may be removed from the membrane. Alternatively, the supporting structure may be porous. A porous supporting structure may be made by a non-woven textile process, a sintering process within an extrusion machine, or by extruding a polymer mixed with a second component. The second component may be a soluble solid or liquid, a super-critical gas, or a second polymer that does not react with the first polymer.
摘要:
A hollow fiber membrane is formed by embedding a braid having a spiral open weave of monofilaments only, to avoid a "whiskering" problem common in prior art multifilament braid-supported tubular membranes. The open weave is characterized by contiguous, circumferential, rhomboid-shaped areas of polymer film separated by mono filaments. When the braid is supported on a plasticized PVA cable it can be infiltrated with membrane polymer which, when coagulated embeds the braid positioning it around the lumen. The spiral weave, free of any circumferentially constricting monofilament, when embedded in film, allows the membrane to be biaxially distensible. In other words, the membrane has "give" not only in the axial or longitudinal direction but also in the radial direction. "Give" in the radial direction permits soiled membranes to be backwashed under higher pressure than in a comparable braid which is not radially distensible.