EP0589891A4 - Polymeres cristallins liquides a resistance elevee a la compression ainsi que leurs fibres et leurs films. - Google Patents

Polymeres cristallins liquides a resistance elevee a la compression ainsi que leurs fibres et leurs films.

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Publication number
EP0589891A4
EP0589891A4 EP19920907397 EP92907397A EP0589891A4 EP 0589891 A4 EP0589891 A4 EP 0589891A4 EP 19920907397 EP19920907397 EP 19920907397 EP 92907397 A EP92907397 A EP 92907397A EP 0589891 A4 EP0589891 A4 EP 0589891A4
Authority
EP
European Patent Office
Prior art keywords
fiber
articulated
film
compressive strength
liquid crystalline
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19920907397
Other languages
German (de)
English (en)
Other versions
EP0589891A1 (fr
Inventor
Robert F Kovar
Richard W Lusignea
Robert C Evers
Thaddeus A Helminiak
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vencore Services and Solutions Inc
Original Assignee
Foster Miller Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Foster Miller Inc filed Critical Foster Miller Inc
Publication of EP0589891A4 publication Critical patent/EP0589891A4/fr
Publication of EP0589891A1 publication Critical patent/EP0589891A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/22—Polybenzoxazoles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C67/00—Shaping techniques not covered by groups B29C39/00 - B29C65/00, B29C70/00 or B29C73/00
    • B29C67/24—Shaping techniques not covered by groups B29C39/00 - B29C65/00, B29C70/00 or B29C73/00 characterised by the choice of material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D7/00—Producing flat articles, e.g. films or sheets
    • B29D7/01—Films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/08—Polyhydrazides; Polytriazoles; Polyaminotriazoles; Polyoxadiazoles
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/18—Polybenzimidazoles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2079/00—Use of polymers having nitrogen, with or without oxygen or carbon only, in the main chain, not provided for in groups B29K2061/00 - B29K2077/00, as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2081/00—Use of polymers having sulfur, with or without nitrogen, oxygen or carbon only, in the main chain, as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/0079—Liquid crystals

Definitions

  • This invention relates to fibers and films of rigid rod heterocyclic liquid crystalline polymers having improved compressive strength.
  • Ordered polymers are polymers having an "ordered,” orientation in space i.e., linear, circular, star shaped, or the like, imposed thereon by the nature of the monomer units making up the polymer. Most ordered polymers possess a linear "order” due to the linear nature of the monomeric repeating units comprising the polymeric chain. Linear ordered polymers are also known as "rod-like" polymers. As a result of their rigid-rod-like molecular structures, these materials form liquid crystalline solutions, and they are also known as liquid crystalline polymers.
  • U.S. Patent No. 4,423,202 to Choe discloses a process for the production of para-ordered, aromatic heterocyclic polymers having an average molecular weight in the range of from about 10,000 to 30,000.
  • U.S. Patent No. 4,377,546 to Helminiak discloses a process for the preparation of composite films prepared from para-ordered, rod-like, aromatic, heterocyclic polymers embedded in an amorphous heterocyclic system.
  • U.S. Patent Nos. 4,323,493 and 4,321,357 to Keske et al. disclose melt prepared, ordered, linear, crystalline injection moldable polymers containing aliphatic, cycloaliphatic and araliphatic moieties.
  • U.S. Patent No. 4,229,566 to Evers et al. describes para-ordered aromatic heterocyclic polymers characterized by the presence of diphenoxybenzene "swivel" sections in the polymer chain.
  • U.S. Patent No. 4,207,407 to Helminiak et al. discloses composite films prepared from a para-ordered, rod-like aromatic heterocyclic polymer admixed with a flexible, coil-like amorphous heterocyclic polymer.
  • PBZ Polybenzazole
  • PBO polybenzoxazole
  • PBZT polybenzothiazole
  • PBI polybenzimidazole
  • Fig. 1 is a schematic depicting the synthesis of APBTZ.
  • Figs. 2 and 3 are schematic representations of the articulated linkages formed in APBTZ.
  • Fig. 4 is a diagrammatic representation of the morphology of PBZT versus APBTZ.
  • SUBSTITUTE SHEET Fig. 5 is a schematic representation showing the synthesis of one perferred articulated monomer in accordance with the present invention.
  • Fig. 6 is a graph showing mole percent articulation versus intrinsic viscosity.
  • Fig. 7 is a diagrammatic representation of one fiber spinning apparatus for use in the present invention.
  • Fig. 8 is a diagrammatic representation of fiber drying for use in the present invention.
  • Fig. 9 is a schematic representation of a tensile test device for use in practicing the present invention.
  • Fig. 10 is a graph showing mole percent articulation versus compressive strength.
  • Fig. 11 is an illustration of one polymerization apparatus for use in the present invetion.
  • the present invention provides fibers and films having improved compressive strength and methods of making such fibers and films.
  • the fiber or film comprises a rigid-rod, heterocyclic liquid crystalline polymer comprising up to about 25 mole % of at least one articulated monomer unit.
  • the compressive strength of the fiber or film is improved by a factor of about 3 to 4 over the compressive strength of a comparable fiber or film consisting of the rigid-rod, heterocyclic liquid crystalline polymer.
  • Fibers and films wherein the articulated monomer unit is present at up to about 10 mole % are preferred in accordance with the present invention. Up to about 15 mole % articulated monomer unit is particularly preferred, with a mole % of from about 0.5 to about 2.5 mole % being especially preferred.
  • Articulated monomer units for use in the present invention are selected on the basis of compatibility with the properties of the liquid crystalline polymer into which they will be incorporated.
  • the monomer unit must be compatible, for example, with the morphology and thermal properties of the host liquid crystalline polymer, as well as with the chemical properties in so far as how the material is polymerized.
  • the articulated monomer unit must provide the correct spacing and length to allow the articulated polymer formed to fit within the polymer crystal structure.
  • Preferred articulated monomer units for use in the present invention include a 3,3'-biphenyl, 3,3'-triphenyl, 2,2'-bipyridyl, and bis(oxyphynylene)benzene units.
  • Polybenzazole (PBZ) liquid crystalline polymers are one class of preferred rigid-rod, heterocyclic liquid crystalline polymers for use in the present invention.
  • Preferred PBZ polymers are selected from the group consisting of polybenzoxazole (PBO) , polybenzothizole (PBZT) and polybezimidazole (PBI) polymers and random, sequential or block copolymers thereof.
  • the present invention also provides liquid crystalline polymers having less than about 5 mole % articulation, 0.5 to 2.5 mole % articulation being preferred.
  • the improvements which are obtained by the rigid rod heterocyclic liquid crystalline polymer structures of the present invention are predicated upon the unexpected discovery that the compressive properties of such structures are surprisingly improved by incorporation of articulated linkages within the polymer backbone.
  • the present invention provides structures, such as fibers and films, comprising ordered polymers having improved mechanical properties by the incorporation in small amounts of articulated monomer units between long, ordered polymer chain segments.
  • Articulated monomers units for use in the present invention impart a three-dimensional order to the desired liquid crystalline polymer that resists compressive failure and interlaminar shear due to microbuckling.
  • the preferred articulated monomer unit comprises a "flexible swivel group.” Such groups are disclosed in U.S. Patent No. 4,229,566, supra; Evers and Moore, J. Polymer Sci. , 24 (1986) 1863-1877; and U.S. Patent No. 4,359,567.
  • Fibers and films prepared from articulated liquid crystalline polymer dopes will exhibit enhanced compressive strength and higher interlaminar shear strength as a direct result of three-dimensional molecular interconnectivity.
  • Articulated monomers units for use in the present invention are selected on the basis of compatibility with the properties of the liquid crystalline polymer into which they will be incorporated.
  • the monomer unit must must be compatible, for example, with the morphology and thermal properties of the host liquid crystalline polymer, as well as with the chemical properties in so far as how the material is polymerized.
  • the articulated monomer unit must provide the correct spacing and length to allow the articulated polymer formed to fit within the polymer crystal structure.
  • Polybenzazole (PBZ) liquid crystalline polymers are one class of preferred ordered polymers for use in the present invention.
  • Preferred PBZ polymers are selected from the group consisting of polybenzoxazole (PBO) , polybenzothizole (PBZT) and polybenzimidazole (PBI) polymers and random, sequential or block copolymers thereof.
  • PBZ polymers typically contain a plurality of mer units that are AB-PBZ mer units, as represented in Formula 1(a) , and/or AA/BB-PBZ mer units, as represented in Formula 1(b)
  • Each Ar and Ar' represents an aromatic group.
  • the aromatic group may be heterocyclic, such as a pyridinylene group, but it is preferably carbocyclic.
  • the aromatic group may be a fused or unfused polycyclic system.
  • the aromatic group preferably contains no more than about three six-membered rings, more preferably contains no more than about two six-membered rings and most preferably consists essentially of a single six-membered ring.
  • suitable aromatic groups include phenylene moieties, biphenylene moieties and bisphenylene ether moieties.
  • Each Ar and Ar' is most preferably a 1,2,4,5-phenylene moiety, except wherein a predetermined percent of Ar groups is replaced with articulated monomer units in accordance with the present invention for use in producing structures having enhanced compressive strength.
  • Each Z is independently an oxygen atom, a sulfur atom or a nitrogen atom bonded to an alkyl group or a hydrogen atom.
  • Each Z is preferably oxygen or sulfur (the polymer is preferably PBO, PBZT or a copolymer thereof) ;
  • Each DM is independently a bond or a divalent organic moiety that does not interfere with the synthesis, fabrication or use of the polymer.
  • the divalent organic moiety may contain an aliphatic group (preferably C ⁇ to C 12 ) ' but tne divalent organic moiety is preferably an aromatic group (Ar or Ar') as previously described.
  • each azole ring is bonded to adjacent carbon atoms in the aromatic group, such that a five-membered azole ring fused with the aromatic group is formed.
  • azole rings in AA/BB-PBZ mer units may be in cis- or trans-position with respect to each other, as illustrated in 11 Ency. Polv. Sci. & Eog., 601, at 602, (J. Wiley & Sons 1988) which is incorporated herein by reference.
  • the PBZ polymer may be rigid rod, semirigid rod or flexible coil. It is preferably rigid rod in the case of an AA/BB-PBZ polymer or semirigid in the case of an AB-PBZ polymer. It more preferably consists essentially of AA/BB-PBZ mer units. Exemplary highly preferred unmodified mer units, i.e., before articulation in accordance with the present invention, are illustrated in Formulas 2 (a)-(f).
  • the unmodified polybenzazole polymer most preferably consists essentially either of the mer units illustrated Formula 2(a) (cis-PBO) or of the mer units illustrated in Formula 2(c) (trans-PBZT) .
  • Each unmodified polymer preferably contains on average at least about 25 mer units, more preferably at least about 50 mer units and most preferably at least about 100 mer units.
  • the intrinsic viscosity of unmodified cis-PBO or trans-PBZT in methanesulfonic acid at 25°C is preferably at least about 10 dL/g, more preferably at least about 20 dL/g and most preferably at least about 30 dL/g.
  • articulated monomer units comprising 3,3'-biphenyl linkages into the backbone of PBZT.
  • the invention is not limited to this articulated monomer.
  • Preferred articulated monomers for use with PBZT polymers are disclosed, for example, in U.S. Patent Nos. 4,229,566; and Evers and Moore; and U.S. Pat. No. 4,359,567; supra.
  • Preferred monomer units for use in the present invention include 3,3'-biphenyl, 3,3'-triphenyl, 2,2'-bipyridyl, and bis(oxyphenylene) benzene units.
  • Articulated monomer units comprising 3,3'-biphenyl units are particularly preferred for preparing modified, i.e., articulated. polymers in accordance with the present invention.
  • the articulated monomer unit chosen must have the correct dimensions to align with two adjacent layers of polymers in the film.
  • the mole percent of articulated monomer unit incorporated into rigid-rod, heterocyclic liquid crystalline polymers in accordance with the present invention will vary depending upon the polymer and monomer selected, as well as the desired end use for such articulated polymer. Up to about 25 mole % articulation is expected to be useful in the practice of the present invention. A preferred mole % articulation is between 0.1 to 10 mole %, 0.5 to 2.5 mole % articulation being particularly preferred.
  • Fig. 1 illustrates one embodiment of the present invention wherein the articulated monomer unit 3,3'-bis(carboxy)biphenyl is incorporated into the polymer backbone of PBZT.
  • the 3,3'-bis(carboxy)biphenyl monomer unit was chosen for this embodiment of the present invention, because it exhibited bond lengths and bond angles that enabled the development of the desired APBZT morphology shown in Figs. 3 and 4.
  • APBZT crystallines contain molecules linking the aligned PBZT rigid-rod molecules.
  • the all-aromatic structure of this monomer also provided thermal and oxidative stability that was comparable to the aromatic PBZT molecule itself.
  • the rigid rod With the articulation present within the polymer, the rigid rod is able to rotate and swivel at this linkage. With one portion of the PBZT molecule in the plane, another portion of the molecule can rotate and protrude out of the plane as shown in Fig. 3.
  • the APBZT has significantly increased intermolecular and interlayer interaction through this three-dimensional reinforcement.
  • Fig. 4 illustrates the interaction between articulated molecules versus non-articulated molecules of PBZT.
  • a stoichiometric amount of terephthalic acid (“TPA”) comonomer was added to the flask along with sufficient P2°5 to produce PPA of 83 percent P 2 0 5 content and the flask was heated rapidly to the polymerization temperature of 170°C. After 24 hours at that temperature, the reaction flask was heated to 195°C for an additional 24 hours to complete the polymerization reaction. At this point, a viscous, yellow-green dope of APBZT formed.
  • PBZT polymer was also prepared to serve as the control for comparison with APBZT polymers during fiber and film testing.
  • PBZT and APBZT polymers of high molecular weight were produced as evidenced by high intrinsic viscosity values measured for PBZT and APBZT polymers.
  • APBZT polymers were prepared containing 2.5, 5, 7.5, 10, and 15 mole percent articulated units within the PBZT backbone.
  • Figure 6 illustrates the variation of intrinsic viscosity (IV) with degree of articulation for APBZT polymers prepared.
  • Samples of 0, 5, and 10 mole percent APBZT polymer dopes in polyphosphoric acid solution were extruded into fibers and vacuum-cast into films.
  • PBZT and APBZT polymer dopes were spun into fibers from 15 wt % solids solutions in PPA, using the apparatus shown in Fig. 7 and dried using the apparatus of Fig. 8. The resultant fibers were characterized with respect to tensile and compressive strength.
  • Fig. 9 illustrates the structure of a fiber compression test specimen.
  • APBZT fiber compressive strength rapidly increased, then decreased with increasing articulated linkage content, the best results being obtained at 2.5 mole % articulated monomer content as shown in Fig. 10.
  • Tensile strength decreased linearly with increasing degree of articulation. However, it is expected that higher tensile strength values will be obtained at articulation levels lower than 2.5 mole %, between 1 and 2 mole %, as well as improved compressive strength.
  • Multiaxially oriented films comprising articulated rigid-rod, heterocyclic liquid crystalline polymers and having improved compressive strength, e.g., by a factor of 3 to 4, over comparable films of the non-articulated polymer, may be prepared following the teachings of U.S. Patent Nos. 4,939,235; 4,973,442; and 4,962,428, suora.
  • a curved argon inlet tube 1 directed the constant argon purge toward the bottom of the flask.
  • Argon was chosen in place of nitrogen because it was heavier than air and tended to drift toward the bottom of the flask, keeping the contents blanketed with inert atmosphere at all times.
  • a vacuum-regulator 2 allowed degassing of the entire flask under high vacuum while continuing to purge with argon makeup gas.
  • the high torque stirrer motor 3 was required to stir viscous PBZT dopes continuously, even at very low rotational speeds.
  • An outlet tube 4 on the reactor vessel directed argon and volatiles from the
  • a fourth opening to the flask 7 was used for the addition of P 2 °5 and PBZT monomers.
  • Monomers and P 2 0 5 were added to the flask through a dry glass tube fitted with a wide funnel to prevent spillage.
  • the tube was extended into the flask to a level close to the surface of the reactant mixture to ensure placement of monomer directly onto the surface of the reactant mixture.
  • a thin wire was used to dislodge small amounts of monomer if they became trapped within the addition tube.
  • the entire reaction flask was oven-dried at 100°C for several hours before use, along with any glassware that was to be used in the experiment.
  • DABDT 2,5-diamino-l,4-benzendithiol dihydrochloride
  • TPA micronized terephthalic acid
  • PPA solvent was used at two P2°5 concentrations during the PBZT polymerizations.
  • the first function of the PPA was to dehydrochlorinate the DABDT. Preparing a 77 percent P 2 0 5 content PPA solution produced a solution strong enough for dehydrochlorination but still of sufficiently low viscosity for rapid devolatization of evolving HC1.
  • the second function of PPA was to solubilize the PBZT polymer.
  • a P 2 0s content PPA of 83 percent was required to maintain solubility of the PBZT polymer, but at the 83 percent level was too viscous for dehydrochlorination.
  • the requisite P 0 5 contents will be achieved by adding P 2 °5 powder directly before the polymerization but after the dehydrochlorination was completed.
  • the crystals were filtered, air dried quickly, and vacuum dried for 2 hours at 60°C argon replaced the vacuum in the drying pistol.
  • the yield of crystals (MP 149°C) was about 70 percent for a recovered weight of 17.86 grams.
  • the monomer-grade TPC crystals were then immediately weighed for addition to the polymerization.
  • the flask was heated from 80°C to 170°C and remained for 48 hours.
  • the polymer formed was removed by using the Haake Buchler Mixer Rheometer, the dope was later upgraded outside the flask.
  • a sample of APBZT dope was pressed and coagulated in a neutral water bath for 48 hours. After the acid was extracted out of the APBZT dope, the disc of pressed dope was fibrillated and vacuum filtered. When the pH of the wash water was over 5.0, the fibers were vacuum air dried for another half an hour. At 165°C, the fibers were vacuum dried for 5 hours to remove any residual moisture.
  • MSA methanesulfonic acid
  • the metal stirrer, using the Haake Buchler Mixer, and using the acid chloride form of terephthalic acid all contributed positively to the increased viscosity of the polymer.
  • PBZT and APBZT dopes prepared in accordance with Example 1 were pressure-filtered and degassed prior to fiber extrusion.
  • the fiber extrusion equipment included a screw driven ram extruder with a funnel shaped lO ⁇ extrusion die. This was coupled to a water bath and take-up system that maintained tension in the fiber at all times, while it was drawn on a pre-set draw ratio and wound upon a 10 inch diameter drum. The large diameter of the drum prevented kinking and damage to the fiber due to compressive failure.
  • the extruder was filled with APBZT do and fibers were extruded at two different draw ratios, namely, 10 to 1 and 5 to 1. It was predicted at this time that the lower draw ratio would produce a higher compressive strength fiber, since more three-dimensional order would be preserved. However, in some cases a higher draw ratio may be desirable where it is sought to maximize compressive as well as tensile strength.
  • Preliminary drying of wet fiber was conducted at a temperature of 200°C, a temperature that had been successfully applied to the drying of previous PBZT fibers. Heat-treatment was performed at 535°C, since that temperature had also produced PBZT fibers with the highest mechanical properties Fiber tension was maintained throughout each operation to prevent damage due to abrasion or kinking.
  • Heat-treated PBZT and APBZT f bers prepared in accordance with Example 2 were tested for compressive strength using the single fiber recoil compression test procedure developed by the Air Force Materials Laboratory (See, e.g., Takahashi et al, J. Appl. Poly. Sci. 28, 579-586 (1983); DeTeresa et al., J. Mat. Sci. 19, 57-72 (1984); Allen, J. Mat. Sci. 22, 853 (1987); DeTeresa et al, J. Mat. Sci. 20, 1645 (1985) ; and DeTeresa, J. Mat. Sci. 23, 1886 (1988)).
  • This test was conducted as follows:
  • a fiber specimen was mounted within a tensile test fixture as illustrated by Fig. 9. The fiber was then examined under the microscope for the absence of kink bands or other defects and measured with respected to average fiber diameter along its length.
  • the fiber was tensioned to a predetermined load which was somewhere below the ultimate tensile failure load for the fiber.
  • An electric arc was used to sever the fiber instantaneously, without causing spikes in the fiber tensile load.
  • the severed fiber specimen was re-examined under the microscope for the presence of kink bands at either side of the specimen. The presence of a dark, swollen kink band, usually situated at the junction between fiber and epoxy potting droplet, was indication of compressive failure for that end of the fiber.
  • Fail/No Fail notations were recorded for gradually changing tensile loads, with a load being reached where neither end of the fiber developed any kink bands. This load, divided by the average fiber diameter, represented the fiber recoil compression strength of the fiber specimen.
  • Fig. 10 illustrates the results of the fiber recoil compression strength tests involving PBZT and APBZT fibers. The tests indicated significant improvement in PBZT fiber compressive strength by incorporation of articulated linkages, at low loadings, within the polymer backbone.
  • SUBSTITUTE SHEET approximately 14% in 2.5 mole % APBZT fibers in comparison to PBZT fiber. However, improved tensile strength values are expected to be obtained at articulation levels lower than 2.5 % (between 1-2%).

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Macromolecular Compounds Obtained By Forming Nitrogen-Containing Linkages In General (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)
  • Artificial Filaments (AREA)

Abstract

Fibres et films de polymères cristallins liquides articulés présentant des propriétés améliorées de résistance à la compression, et polymères cristallins liquides articulés présentant moins d'environ 5 mole % d'unités de monomères articulés.
EP92907397A 1991-02-19 1992-02-18 Polymeres cristallins liquides a resistance elevee a la compression ainsi que leurs fibres et leurs films Withdrawn EP0589891A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US65775591A 1991-02-19 1991-02-19
US657755 1991-02-19
PCT/US1992/001282 WO1992014776A1 (fr) 1991-02-19 1992-02-18 Polymeres cristallins liquides a resistance elevee a la compression ainsi que leurs fibres et leurs films

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EP0589891A4 true EP0589891A4 (fr) 1993-11-11
EP0589891A1 EP0589891A1 (fr) 1994-04-06

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JP (1) JPH06502228A (fr)
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CN102977348B (zh) * 2012-12-13 2013-11-13 江苏腾盛纺织科技集团有限公司 含噁唑结构的嵌段共聚酯树脂及其制备方法及高强度共聚酯纤维
CN103012764B (zh) * 2012-12-13 2013-11-13 江苏腾盛纺织科技集团有限公司 含噁唑结构的无规共聚酯树脂及其制备方法及高强度共聚酯纤维
CN117364273B (zh) * 2023-10-10 2024-04-26 江苏亨博复合材料有限公司 一种横向增强的pbo纤维的制备方法

Citations (3)

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US4263245A (en) * 1979-04-23 1981-04-21 Celanese Corporation Process for producing high-strength, ultralow denier polybenzimidazole (PBI) filaments
US4359567A (en) * 1981-10-02 1982-11-16 The United States Of America As Represented By The Secretary Of The Air Force Thermooxidatively stable articulated p-benzobisoxazole and p-benzobisthiazole polymers
WO1990006349A1 (fr) * 1988-11-28 1990-06-14 The United States Department Of Energy Compositions polymeres contenant une grande quantite de cristaux liquides

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US4263245A (en) * 1979-04-23 1981-04-21 Celanese Corporation Process for producing high-strength, ultralow denier polybenzimidazole (PBI) filaments
US4359567A (en) * 1981-10-02 1982-11-16 The United States Of America As Represented By The Secretary Of The Air Force Thermooxidatively stable articulated p-benzobisoxazole and p-benzobisthiazole polymers
WO1990006349A1 (fr) * 1988-11-28 1990-06-14 The United States Department Of Energy Compositions polymeres contenant une grande quantite de cristaux liquides

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EP0589891A1 (fr) 1994-04-06
CA2104378A1 (fr) 1992-08-20
WO1992014776A1 (fr) 1992-09-03

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