Abstract: The present invention relates to microporous and ultrafine polytetrafluoroethylene (PTFE) membranes of high permeability, excellent mechanical strength, and good chemical inertness, and to methods for their preparation. According to the method of the present invention, a porous PTFE substrate having a first pore rating is compressed to provide a porous membrane having a second pore rating, wherein the second pore rating is smaller than the first pore rating. The PTFE substrate can be contacted with one or more fibrous sheets during the compression step, which is preferably performed by passing the substrate, and fibrous sheets, if appropriate, between two calender rolls. The resulting porous PTFE membrane then can optionally be stretched and/or sintered, and preferably has a water permeability of at least about 0.5 l/hr/m2/kPa.

Abstract: Nonwoven webs in accordance with the present invention include multicomponent fibers bonded by a multiplicity of bond sites to form a coherent web. The multicomponent fibers include a first component formed of a hydrophobic polypropylene and a second component formed of a blend of a hydrophobic polyolefin and a hydrophilic melt additive. This second component is disposed at the surface of the fibers. The hydrophilic melt additive-modified polyolefin component can be arranged in various configurations in the cross-section of the fiber and the fibers can have various cross sections. For example, the hydrophilic component can occupy a portion of the surface of the fiber, as would occur for example with a side-by-side or segmented pie multicomponent fiber configuration. Alternatively, the modified hydrophilic polyolefin can occupy substantially the entire surface of fiber, as for example by producing the fibers in a sheath core configuration with the hydrophilic modified component forming the sheath.

Abstract: A filter medium which has an average pore diameter of more than 0.5 &mgr;m, a pressure loss of 2-50 mmH2O determined when air is permeated therethrough at a velocity of flow of 5.3 cm/sec, and a PF value of 18-12, which is calculated in accordance with the following equation on the basis of this pressure loss and a collection efficiency using DOP of a grain size of 0.10-0.12 &mgr;m.

Abstract: An apparatus and a method for making a transfer device comprising a tube bundle. The transfer device is suitable for use as a heat exchanger in a blood cardioplegia circuit, for example. The apparatus axially winds a flexible tube around a winding core. The apparatus includes a winding core, a core rotating means, a tube bobbin, and a tube shuttle to guide the tube around the core. A shuttle rotating means rotates the tube shuttle around the core. The method of making the transfer device includes providing a winding core, winding a tube from end to end around the winding core, fitting the wound bundle into a housing, sealing the first and second ends of the housing using a potting material, cutting the ends of the bundle to expose a lumen within the tubes, and attaching a first end cap and a second end cap.

Abstract: An integral composite membrane is provided including a porous polymeric membrane impregnated with a perfluoro ion exchange material to make the micropores of the membrane occlusive and a surfactant having a molecular weight greater than 100 wherein the thickness of the composite membrane is less than 0.025 mm. Methods for making and regenerating the integral composite membrane are also provided.

Abstract: A filter useful for the ultrafiltration and microfiltration of aqueous suspensions includes a microporous membrane structure that has pores of size effective to reject particles in the range of about 0.01-10 &mgr;m. At least a portion of the membrane structure in contact with the suspension has a surface energy less than that of polytetrafluoroethylene. Low surface energy can be achieved by coating a microporous substrate with a substance such as fluorine substituted dioxole polymer. The filter has superior resistance to fouling by species suspended in the aqueous suspension and can continuously filter flow of such suspension in excess of 100 L/(m2−h) for more than 150 hours. The new filter is useful in many traditionally fouling prone ultrafiltration and microfiltration membrane applications such as the filtering of shipboard generated graywater waste.

Abstract: A method for casting-in-place composite and/or non-filled structures which are useful as sorptive or reactive media or for size-based separations. Any particular housing size or configuration can be used, and the inclusion of a large amount of adsorptive particles in polymer is achieved while still maintaining the membrane three dimensional structure. In a first preferred embodiment, the composite structures comprise particles entrapped within a porous polymeric substrate, and are cast in-place into a housing such as a pipette tip, thereby providing an effective platform for micromass handling. With the appropriate selection of particle chemistry, virtually any separation or purification operation can be conducted, including selective bind/elute chromatography operations, on sample mass loads less than 1 microgram in volumes of a few microliters, as well as larger mass loads and volumes. The present invention also encompasses the composite structures as well as sample preparation devices containing the same.

Abstract: An article, such as a filter or film, has a treated laminate with an expanded PTFE membrane and a porous support scrim. The treated laminate is formed by contacting a laminate having an expanded PTFE membrane and a porous support scrim with an oleophobic treatment agent dissolved in an organic solvent. The oleophobic treatment agent is deposited onto the expanded PTFE membrane and porous support scrim as the organic solvent is removed. The oleophobic treatment agent is typically a fluoropolymer. The article can be used, for example, as a filter over a port in a housing of an electronics or other device.

Abstract: A non-cracking hydrophilic polyether sulfone membrane is prepared by (a) directly coating the entire surface of a hydrophobic polyethersulfone membrane with an aqueous solution of a polyalkylene oxide polymer and at least one polyfunctional monomer, and (b) polymerizing the monomer over the entire surface of the membrane under conditions which cause the resulting polymer to attach to the polyethersulfone membrane and the polyethylene oxide to form a non-extractable surface which does not crack when the membrane is folded to form a pleated cartridge.

Abstract: A porous membrane is provided which is formed from a porous polyperfluorocarbon membrane substrate having its surface modified with a perfluorocarbon polymer composition. The modified surface is directly wet with an aqueous liquid.

Abstract: An ultra-thin composite membrane is provided which includes a base material and an ion exchange resin. The base material is a membrane which is defined by a thickness of less than 1 mil (0.025 mm) 0.8 mils and a microstructure characterized by node interconnected by fibrils, or a microstructure characterized by fibrils with no nodes present. The ion exchange resin substantially impregnates the membrane such that the membrane is essentially air impermeable.