The Dow Chemical Company

Jang-hi Im

C C Chau

Chieh-Chun Chau

Ritchie A Wessling

Lu H Tung

Rexford Allison Maugans

Tooru Kitagawa

Takaharu Ichiryu

Hiroki Murase

Otto C Raspor

William E Shrum

David R Kiesel

Polybenzazole fibers can be rapidly dried without undue fiber damage by exposing them to two or more set point temperatures with the temperatures being selected relative to the residual moisture content of the fiber. The residence time required for the fiber at each progressively higher temperature can be reduced if the fiber is always in full contact with the set point temperature of the drying equipment.

Method for rapid drying of a polybenzazole fiber

Improved polybenzoxazole fibers are made by a process for drying a wet, coagulated polybenzoxazole (PBO) fiber including the steps of:

Process for post-spin finishing of polybenzoxazole fibers

A multilayer film is provided in the form of an extruded sheet for food wrapping and cooking procedures. The film is made up of alternating layers of a first generally ductile material and a second generally brittle material. Upon wrapping a food item or container, the film exhibits dead fold and/or twistability characteristics. In one embodiment, the materials of the film are chosen to have softening points above about 450 degrees F. so that the film can be used in conventional ovens.

Multilayer film with dead fold and twistability characteristics

A process for preparing microporous membranes by coextruding a melt of a plurality of interdigitated layers of at least two polymers, one having preferential solubility over the other, dividing and reorienting the layers of said melt into discrete domains of random orientation, forming a thin membrane or like article and leaching the preferentially soluble polymer out of the resulting article.

Process for preparing microporous membranes

A method for preparing porous membranes containing a homogeneous microporous structure and narrow pore size distribution which are useful for ultrafiltration, distillation and substrates for composite membranes, including preparing films, pellets or sheets containing alternating microlayers of high density polyethylene and polystyrene, recoextruding these films, pellets or sheets, pulverizing into fine granules or powder, compression molding or sintering into thin films, immersing these films in a solvent bath into which one component is selectively dissolved and separating the resultant porous membrane from the solvent.

Process of making a porous membrane

A method for preparing an asymmetric, semi-permeable membrane containing a uniform microporous structure for gas and liquid separation, including forming a dense separation on one major surface of a microporous support structure. The microporous support structure is initially formed as a solid unitary film, fiber or sheet by the simultaneous extrusion of at least two streams of heat-plastified polymeric materials including at least two differentially soluble polymeric materials. The separation layer can be formed on the support structure prior to or after the soluble polymeric material has been dissolved out of, as by leaching from the solid support structure to form the microporous support for the separation layer. Preparation in this manner greatly reduces the tendency to form undesiralbe pinholes in the membrane.

Method for preparing an asymmetric semi-permeable membrane

There is disclosed a separator medium for fluid-activated primary electrochemical battery cells of the reserve type. The separator medium comprises a thin, substantially impermeable film of a Lewis base polymer which is soluble in the activating electrolyte solution.

Temporary barrier layer in batteries

Multilayer coextruded piezoelectric/pyroelectric elements and method for manufacturing these elements are disclosed. The layer configuration of the element permits easy application of conductive material to two separate faces and thus prevents short-circuiting.

Method of making piezoelectric/pyroelectric elements

Laminated articles in the form of an extruded sheet have a multi-layered structure and comprise, on the average, alternating layers of coextruded polymeric thermoplastic materials, wherein one of said materials comprises a carbonate polymer. The articles exhibit good impact resistance even when scratched or notched, hydrolytic stability and transparency.

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Midland, MI, United States of America

Jang-hi Im