The present invention relates to microporous materials incorporating a nucleating agent and methods for making the same The method comprises the steps of melt blending a crystallizable thermoplastic polymer with a nucleating agent which is capable of inducing subsequent crystallization of the thermoplastic polymer and with a compound which is miscible with the thermoplastic polymer at the melting temperature of the polymer but phase separates on cooling at or below the crystallization temperature of the polymer, forming a shaped article of the melt blend, cooling the shaped article to a temperature at which the nucleating agent induces the thermoplastic polymer to crystallize so as to cause phase separation to occur between the thermoplastic polymer and the compound, thereby providing an article comprising an aggregate of a first phase comprising particles of crystallized thermoplastic polymer in a second phase of the compound, and stretching the article in at least one direction to provide a network of interconnected micropores throughout Preferably, the compound is removed either before or after stretching The use of a nucleating agent in accordance with the present invention provides for the manufacture of a wide variety of microporous materials heretofore not possible having a wide range of porosity and other physical characteristics

Microporous materials incorporating a nucleating agent and methods for making same

Structural study of microporous polypropylene hollow fiber membranes made by the melt-spinning and cold-stretching method

The invention provides extraction columns for the purification of an analyte (e.g., a biological macromolecule, such as a peptide, protein or nucleic acid) from a sample solution, as well as methods for making and using such columns. The invention is characterized by the use of low dead volume columns, which is achieved in part by the use of low pore volume frits (e.g., membrane screens) to contain a bed of extraction media in the column. Low dead volume facilitates the elution of the captured analyte into a very small volume of desorption solution, allowing for the preparation of low volume samples containing relatively high concentrations of analyte.

Low dead volume extraction column device

A distinctive technique for making porous fiber includes a stretching of a substantially continuous fiber while the fiber is in an operative association with an effective quantity of surface-active material The fiber can be produced from a source material which includes a thermoplastic, orientable material and at least about 035 weight percent (wt %) of a supplemental material In particular configurations of the invention, the fiber may be contacted with a first quantity of surface-active fluid and at least a separate, second quantity of surface-active fluid In other configurations, the fiber may be subjected to an additional incremental stretching

Process for making microporous fibers with improved properties

A porous polypropylene hollow fiber membrane constructed and arranged for artificial lung use and an artificial lung. The membrane includes a solid phase in an inner surface region thereof formed with particles of polypropylene closely fused and joined to give rise to a continuous phase while partially exposed through the surface thereof, a solid phase in an interior and an outer surface region thereof formed with particles of polypropylene interconnected in the direction of axis of the fiber to give rise to a multiplicity of lumps of polyproplylene and an interstice between the phases having continuous pores interconnected in the form of a three-dimensional network.

Porous polypropylene membrane and method for production thereof

A porous hollow fiber membrane, comprising a polyolefin hollow fiber membrane of an annular cross section of substantial circle 150 to 300 μm in inside diameter and 10 to 150 μm in wall thickness, said hollow fiber membrane forming on the inner wall side thereof a tight layer of intimately bound fine polyolefin particles and on the outer wall side thereof a porous texture of fine polyolefin particles bound in chains and containing fine pores extended continuously form said inner wall side to said outer wall side.

Hollow fiber membrane and method for manufacture thereof

PURPOSE:To obtain a hollow yarn membrane which has high gas exchange ability and is suitable for the artificial lungs by forming an approximately circular polyolefin hollow yarn membrane the inside surface side of which is the dense layer of fine polyolefin particles and the outside surface side of which is a porous layer bound with the fine polyolefin particles in a chain state. CONSTITUTION:The blend of polyolefin, an org. filler such as liquid paraffin and a crystal nucleus forming agent such as 1.3, 2.4-dibenzylidene sorbitol is melted and kneaded and thereafter the mixture is discharged from an annular spinning hole into air; at the same time an inert gas is introduced to the inside center to form a hollow material. The hollow material is brought into contact with a cooling and solidifying liquid and is taken up on a bobbin. The org. filler is extracted away by an extraction liquid. The resulted hollow yarn membrane 1 has approximately the circular shape whose inside diameter D is 150-300mum and the wall thickness T is 10-150mum. The inside surface side of the membrane is the relatively dense layer 2 and the outside surface side is the porous layer 3 bound with the fine polyolefin particles having about 0.01-1.0mum average grain size in a chain state. The fine through-holes are formed from the inside to the outside surface side.

Emi Makoto

Papers

Hollow fiber membrane and method for manufacture thereof

Hollow yarn membrane and its production

Hollow fibre membrane

Flat permeable polyolefin membranes