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.
摘要:
The method comprises the successive steps of: placing a support in an end section of the pipe, heating the pipe in the region of the end section; deforming the pipe to produce a socket in the region of the heated end section; the heated end section being supported internally while the socket is being formed; cooling the pipe in the region of the end section, the end section being supported internally during the cooling operation; and removing the support from the pipe, for the purpose of heating the internally supported end section of the pipe, said end section first being heated until said end section has reached, substantially homogeneously, the glass transition temperature of polyvinyl chloride and then being further heated until the end section has reached, substantially homogeneously, a temperature near, preferably just above, the orientation temperature of polyvinyl chloride.