Celanese Gmbh

Hoechst Celanese Corporation

Polyplastics Co., Ltd.

Yoshiaki Ide

Hyun Nam Yoon

Gabor D Kiss

Alan Buckley

Kurt F Wissbrun

The present invention provides a highly elongated member of substantially uniform cross-sectional configuration which is capable of improved service as a stiffening support in an optical fiber cable. Such elongated member is the product of melt extrusion through an appropriate orifice of a thermotropic liquid crystalline polymer (as described). The resulting elongated member has been found to offer significant advantages when compared to stiffening supports heretofore proposed for use in optical fiber cables.

Melt extruded elongated member suitable for improved service as a

A fiber-optic cable has reinforcement in the form of an elongated member such as a hollow tube, a member of solid circular cross-section, a channel member and/or an outer jacket formed of a thermotropic liquid crystalline polymer. That polymer has a coefficient of linear thermal expansion in the range of from -10.times.10.sup.-6 /.degree.F. to -4.times.10.sup.-6 /.degree.F. The reinforcing members constitute strength members which are preferably formed separate from, or simultaneously with, the introduction of an optical fiber.

Optical fiber cable and method for producing same

Provided is a process for the extrusion of shaped articles which comprises extruding a thermotropic liquid crystal polymer through a short land or preferably no land die, and with subsequent drawdown of the extruded profile being such as to render a drawdown ratio of less than 4, and preferably about 1. Such extrusion of liquid crystal polymers in accordance with the present invention can consistently and reproducibly provide one with an article of high mechanical properties, and thus, particular advantage is found in employing the process to extrude an article of cross-sectional dimensions which must closely approximate those of the extrusion die without sacrificing high mechanical properties.

Process for extruding thermotropic liquid crystalline polymers

High performance foams comprised of thermotropic liquid crystal polymers are provided. The lightweight rigid foams exhibit a combination of excellent properties including enhanced mechanical properties such as high strength to weight ratio, high flame and thermal stability, and excellent solvent resistance. The foams fabricated from such polymers have significantly reduced anisotropy compared to unfoamed polymers. The transverse mechanical properties are enhanced by foaming relative to the percentage density reduction due to the foaming. The physical properties of the foams are further enhanced by heat treatment as the core of foams of thermotropic liquid crystal polymers consists of highly oriented cell walls which can exhibit greater enhancement upon heat treatment than is exhibited by the core of the unfoamed polymer.

Heat treated high performance foams of thermotropic liquid crystal

High performance foams comprised of certain thermotropic liquid crystal polymers are provided. Such thermotropic liquid crystal polymers comprise not less than about 10 mole percent of recurring 6-oxy-2-naphthoyl moieties. The lightweight rigid foams exhibit a combination of excellent properties including enhanced mechanical properties such as high strength to weight ratio, high flame and thermal stability, and excellent solvent resistance. The foams fabricated from such polymers have significantly reduced anisotropy compared to unfoamed articles of the same polymers.

Lightweight high performance foams of thermotropic liquid crystal

Multiaxially oriented laminates comprised of substantially uniaxially oriented sheets of liquid crystal polymers and a method of production thereof are provided which exhibit desirable mechanical properties and good thermal and chemical resistance. The sheets which comprise the laminate are thermally bonded together and oriented at an angle to one another to provide the multiaxially oriented laminate. The mechanical properties of the laminate can be adapted for specific applications by adjustment of the number, thickness and angle of orientation of each sheet.

Mutiaxially oriented high performance laminates comprised of uniaxially

The present invention provides an improved process for extruding liquid crystal polymer. The process comprises the steps of providing a fluid stream of liquid crystal polymer wherein the stream has a flow pattern comprising substantial shear flow; converting the flow of the fluid stream of liquid crystal polymer to a substantially elongational flow in the substantial absence of shear flow; and extruding the fluid stream of liquid crystal polymer to form a shaped article having the polymer molecules oriented substantially parallel to the flow direction. The resulting articles are self-reinforcing, having mechanical properties superior to conventional extruded liquid crystal polymer articles and comparable to those of articles formed from fiber-reinforced isotropic polymeric materials. In a preferred embodiment, the flow of the fluid stream of liquid crystal polymer is converted to a substantially elongational flow by passing the fluid stream of liquid crystal polymer through at least one grid having a plurality of converging passages (e.g., cone-shaped or trumpet-shaped holes).

Process for extruding liquid crystal polymer

A process for the extrusion of melt processable liquid crystal polymer which provides improved processability characteristics is provided. The process comprises the steps of subjecting the liquid crystal polymer to an elevated temperature between the DSC transition temperature and the degradation temperature of the polymer; cooling the liquid crystal polymer to a processing temperature which is between the DSC transition temperature and the elevated temperature and at which the liquid crystal polymer is less subject to degradation than at the elevated temperature; and extruding the liquid crystal polymer into the form of a shaped article having mechanical properties which are improved over those of articles formed from liquid crystal polymer which has not been subjected to the elevated temperature. Preferably, the liquid crystal polymer exhibits at the elevated temperature a reduction by at least a factor of 5 in the melt viscosity of the liquid crystal polymer, as compared to the melt viscosity at the DSC transition temperature, without significant degradation of the liquid crystal polymer. The reduction in melt viscosity is substantially retained by the liquid crystal polymer at the processing temperature, and the liquid crystal polymer is extruded into the form of a shaped article while the reduction in melt viscosity is thus retained. By employing the process of the present invention, melt processable liquid crystal polymers can be conveniently processed at temperatures near the DSC transition temperature rather than at the higher temperatures commonly encountered in the prior art at which degradation is more likely to occur.

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North Plainfield, NJ, United States of America

Yoshiaki Ide