E.i. Dupont De Nemours and Company

Dupont Canada Inc.

Arthur Z Moss

Edward George Howard, Jr

Edward G Howard

Michael Cregg Coughlin

Kenneth Earl Stevens

George Joseph Ostapchenko

Raymond Richard Zolandz

Martin Gerald Wagner

This invention relates to porous polyfluoroethylene (PTFE), shaped articles prepared therefrom, and to methods of preparing said articles.

Porous polytetrafluoro-ethylene and preparation

Porous polytetraflouroethylene and preparation

Porous polytetrafluoroethylene and preparation

This invention relates to methods for preparing membranes of polyfluoroethylene (PTFE) and to the asymmetric membranes fabricated thereby. Such membranes are useful as separation and ultrafiltration membranes. The membranes are produced as a single layer. Method steps including contacting a substrate with a solution of PTFE in a perfluorinated cycloalkane solvent at a high temperature to cause a film of such solution to be coated on the substrate, removing the coated substrate from the solution and rapidly cooling it by contact with a second solvent, removing the coated substrate from the second solvent, drying the film, and optionally separating film from substrate.

Asymmetric membranes of polytetrafluoroethylene and process for making

The invention provides shaped, substantially unoriented, compositions of PTFE, having high notched Izod impact resistance, produced in a hot compression molding process wherein heat and pressure are applied simultaneously in a selected temperature range below the melting point of the virgin, as polymerized PTFE powder.

Impact resistant polytetrafluoroethylene and preparation thereof

Shaped PTFE compositions are disclosed having low creep which are produced by the application of pressure and elevated temperature. Also disclosed is a process for making shaped compositions with low creep by the application of pressure and elevated temperature.

Polytetrafluoroethylene with improved creep resistance, and preparation

Melt formable thermoplastic resins which exhibit a difference in color between their wet and dry states, processes for melt forming such resins, and the resulting melt formed shaped articles are provided.

Moisture indicating molding resins

A process for extruding a smooth and uniform film or sheet of an ordered poly(ether ketone ketone) having a thickness of about 2.5 to 250 micrometers, wherein the molten extrudate is quenched on a drum maintained at a temperature of about 100.degree.-170.degree. C.

Process for making continuous films of ordered poly(ether ketone ketones)

A film having a porous core layer and nonporous outer layers is made from a composition of certain polymers, particularly ethylene polymers, a particulate filler which has little affinity for the polymer, and optionally an organic compound which decreases the tendency for affinity of the particulate for the polymer. The film is produced by extruding the composition through a die gap of at least 250 .mu.m, and subsequently stretching the film after cooling to a temperature below the melting temperature of the polymer.

Process for making a heterogeneous membrane film

A film having a porous core layer and nonporous outer layers is disclosed. It is suitable for controlled atmosphere packaging end uses. The film is made from a composition of certain polymers, particularly ethylene polymers, a particulate filler which has little affinity for the polymer, and optionally an organic compound which decreases the tendency for affinity of the particulate for the polymer. The film is produced by extruding the composition through a die gap of at least 250 .mu.m, and subsequently stretching the film after cooling to a temperature below the melting temperature of the polymer.

Heterogeneous membranes from highly filled thermoplastic orientable

Microporous polymeric films having good water vapor transmission rates and hydrostatic resistance to the penetration of liquid water are obtained by stretching a composition consisting of a matrix of a thermoplastic orientable polymer having a hydrophobic surface, a glass transition temperature of less than 25.degree. C., a Vicat softening point of more than about 25.degree. C., an ultimate elongation between those two temperatures of at least 100%, and a flexural modulus of less than 200 MPa and a particulate filler having an aspect ratio of less than 3, an average diameter of 0.05-50 m, a negligible attraction to the matrix polymer, and a surface tension no higher than that of the matrix polymer at the latter's melting temperature. Such films are useful in applications involving separation of liquids and vapors, e.g., in making 'breathing' waterproof garments or linings.

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Wilmington, DE, United States of America

Arthur Z Moss