Celanese Gmbh

Hoechst Celanese Corporation

John P Riggs

Hyun Nam Yoon

Frank J Onorato

Paul E McMahon

John M Rhodes

Robert Dix

James A Parker

Richard F Markel

Sang N Kim

Dale T Vest

This invention provides superior electrooptic devices containing an organic polymeric waveguiding medium, and a process of fabricating such devices. The fabrication process utilizes a substantially stress-free organic polymeric substrate on top of which the necessary organic layers are successively deposited. The substrate is so selected that its thermal expansion coefficient is substantially close to that of the cladding layers and of the waveguiding layer.

Polymeric electrooptic waveguide devices using a polymeric substrate

An improved continuous hot gas surface modification process for carbon fibers is provided. The carbon fibers undergoing such processing are passed for a relatively brief residence time through a surface treatment zone to which continuously is fed nitrogen dioxide and air under conditions which have been found to produce a surprisingly effective surface modification. The resulting carbon fibers exhibit a significantly enhanced surface area and an improved ability to bond to a resinous matrix material while retaining a substantial portion of the tensile strength originally exhibited. When incorporated in a resinous matrix material, a fiber reinforced composite article of enhanced interlaminar shear strength is formed.

Process for the surface modification of carbon fibers

A vertical pyrolysis furnace used in the carbonization or high temperature heat treatment of a continuous length of organic fibrous material is disclosed. The oven includes a central conduit or passage having a plurality of independently controlled heating zones disposed circumferentially therearound and spaced axially therealong. The conduit and heating elements are surrounded by suitable insulating material and a gas-tight shell. At the top of the furnace an exhaust manifold is provided which communicates with the central conduit. An environmental seal is provided at the upper end of the exhaust manifold and at the bottom of the conduit. Suitable gaseous inlets communicate with the furnace for an inert gaseous atmosphere which is controlled such that free convection causes the gaseous atmosphere to rise vertically through the central conduit to the exhaust chamber located at the upper end thereof. A continuous length of organic fibrous material moves vertically downwardly through the central conduit from the upper environmental seal to the lower environmental seal. The independently controlled heating zones provide a vertically downwardly increasing temperature gradient, up to a desired maximum value which extends over a prescribed length, which drives off toxic gaseous by-products from the continuous length of organic fibrous material. The heating zone placement and lower environmental seal permit the continuous length of organic fibrous material to cool substantially before exiting to the atmosphere.

Vertical pyrolysis furnace for use in the production of carbon fibers

A process is provided for the stabilization of a fibrous material composed of an acrylic polymer, e.g. an acrylonitrile homopolymer or a closely related copolymer. The fibrous material is subjected to a multiple stage stabilization treatment in which the initial stage is conducted in an essentially inert atmosphere, and a subsequent stage in an atmosphere containing an appreciable quantity of oxygen. The initial treatment which is conducted in a relatively inert atmosphere is believed to result in an improved cyclized molecular structure without encountering excessive chain cleavage, and is followed by an oxygen cross-linking reaction. The stabilized product exhibits improved physical properties. Carbonized or carbonized and graphitized fibrous materials may be formed upon heating the stabilized product in an inert atmosphere.

Acrylic fiber conversion utilizing a stabilization treatment conducted

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New Providence, NJ, United States of America

John P Riggs