CA2023864A1

CA2023864A1 - High strength thermoplastic resin/carbon fiber composites and methods

Info

Publication number: CA2023864A1
Application number: CA002023864A
Authority: CA
Inventors: Rex L. Bobsein; Stuart D. Mills; Mark L. Stone
Original assignee: Phillips Petroleum Co
Current assignee: Phillips Petroleum Co
Priority date: 1989-07-24
Filing date: 1990-08-23
Publication date: 1992-02-24

Abstract

Abstract of the Disclosure High strength thermoplastic resin/carbon fiber compo-sites and methods of producing such composites are provided.
The composites are comprised of carbon fibers, an amine-terminated poly(arylene sulfide) first resin component, and a second resin component selected from the group consisting of poly(arylene sulfides), polyolefins, polysulfones, poly-ether sulfones, polyetherimides, polyetherketones, poly-etheretherketones, polyetherketoneketones, liquid crystal polymers, and mixtures of such resins.

Description

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HIGH STRENGTH THERMOPLASTIC
RESIN/CARBON FIBER COMPOSITES AND METHODS
~ e Invention 1. Field of the Invention This invention relates generally to poly(arylene sulfi-de) composites, and more particularly, to poly(arylene sulfide)/carbon fiber composites having improved adhesion between the resin matrix and the carbon fibers in the com-posite.

2. Description of the Prior Art It has long been appreciated that good adhesion between the resin matrix and the reinforcing fibers utilized in com-posite material is necessary. The usual means employed for enhancing adhesion between the fibers and the resin matrix has been to use a sizing composition ~o coat the fibers before consolidation with the resin matrix.
Sizing compositions operate in generally one of two ways to aid adhesion. The sizing composition may be chemically active and react to form a chemical bond between the fibers and the matrix, or it may form a more compatible surface on the fibers such that the matrix will more readily spread out on and adhere to the fibers. Where the reinforcing fibers have been glass fibers, compositions containing silanes have been successfully employed as sizings to link the glass fibers and the resin matrix.
The use of carbon fibers in composites has involved dif-ferent approaches. In the preparation of the better known and older thermoset resin matrix/carbon fiber composites, a number of proprietary sizing compositions have been employed with varying degrees of success. In recent years there has been a growing interest in composites employing ther-moplastic resin matrices and carbon fibers. Much of this interest is due to the generally greater processability and shelf life of thermoplastics as compared to thermoset resins as well as to the greater chemical resistance and moisture resistance of thermoplastics such as the poly(arylene sulfides).

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Well known poly(arylene sulfides) are poly(phenylene sulfide) and poly(phenylene sulfide/sulfone) which are com-mercially available under the trademark RYTON~ from the Phillips Petroleum Company, Bartlesville, Oklahoma. Such resins are particularly suitable for use in composiites because of their excellent rigidity and heat and electrical resistance as compared to other thermplastic resins.
Thermoplastic resins, however, pose a number of problems in terms of obtaining composites with good adhesion to reinforcing carbon fibers. The same chemical resistance and relatively low chemical activity which make ther-moplastics such as poly(phenylene sulfide) and poly(phenylene sulfide/sulfone) attractive for use in composites, also inhibit effective adhesion to carbon fibers through chemical bonding. Most thermoplastic resins are of a more viscous nature than thermoset resins, and therefore do not physically spread onto carbon fibers as well as thermoset resins. Also, most of the sizing com-positions that have been traditionally employed in the ther-moset resin composites degrade at the temperatures required to process thermoplastic resins such as the poly(arylene sulfides). Thus, there is a need for a method of producing thermoplastic resin/carbon fiber composites having improved adhesion between the thermoplastic matrices and the czrbon fibers as well as for the composites so produced, par-ticularly carbon fiber composites formed of poly(arylene sulfide) and poly(arylene sulfide/sulfone) resins.

Summary of the Invention The present invention fulfills the above-mentioned needs by providing carbon fiber reinforced thermoplastic resin composites having improved adhesion between the carbon fibers and the surrounding resin matrices as measured by improvements in transverse tensile and compressive strengths, and by providing methods of producing such com-posites.
The composites are basically each comprised of carbon : . : : . .

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fibers, an amine-termiated poly(arylene sulfide) first com-ponent and a second thermoplastic resin component selected from the group consisting of poly(arylene sulfides), polyolefins, polysulfones, polyether sulfones, polyetherimi-des, polyetherketones, polyetheretherketones, polyether-ketone-ketones, liquid crystal polymers, and mixtures of such resins. In a most preferred embodiment, the second component is comprised of poly(phenylene sulfide) resin.
The amine-terminated poly(arylene sulfide) first resin component i9 produced by the addition of an amino-organic thiol compound to a polymerization recipe for a poly(arylene sulfide) prior to the substantial completion of the poly-merization. The amine-terminated polymers produced have melt flow rates in the range of from about 10 to about 5000 grams per 10 minutes (as determined by ASTM D-1238, con-dition 317/0.36, using a 1.250 inch long orifice), and func-tion in a carbon fiber containing composite to improve the adhesion of the thermoplastic matrix to the carbon fibers.
Generally, improvement in such adhesion and an improved com-posite results when the amine-terminated poly(arylene sulfi~
de) component is present in the thermoplastic resin matrix in an amount as low as about 0.5% by weight of the total resin.
The methods of the present invention for producing the above-described improved thermoplastic resin/carbon fiber composites basically comprise combining the components uti-lized in the composites, i.e., the carbon fibers, the amine-terminated poly(arylene sulfide) first component and the thermoplastic resin second component, followed by forming a composite from the mixture. Various techniques can be uti-lized for combining the carbon fibers and thermoplastic resin components and forming a composite therefrom, includ-ing injection molding and pultrusion. A preferred method of this invention utilizes a pultrusion technique wherein a continuous fiber roving is pulled through a resin matrix comprised of a mixture of the amine-terminated poly(arylene sulfide) first component and thermoplastic resin second com-.. : ~ . ~, , , -4- 2~(;3~

ponent. The fiber roving is impregnated with the resin mix-ture and is thereafter pulled through a heated forming die which consolidates the carbon fibers and resin matrix into a composite. Variations in the pultrusion process include pulling the carbon fiber roving through the amine-terminated poly(arylene sulfide) component whereby the carbon fibers are impregnated therewith and then pulling the impregnated roving through the thermoplastic resin second component whereby ~he second component resin is deposited on the roving followed by passing the roving through a heated forming die. -It is, therefore, an object of the present invention to provide thermoplastic resin/carbon fiber composites which possess improved adhesion between the resin matrices and the -reinforcing carbon fibers.
A further object of the present invention is the provi-sion of methods for producing thermoplastic resin/carbon fiber composites having improved adhesion between the resin and fibers.
Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of pre- ~ -ferred embodiments which follows. ~;;-::
Description of the Preferred Embodiments . .
As mentioned above, the thermoplastic resin/carbon fiber composites of this invention which have improved adhesion of the thermoplastic resin to the carbon fibers and consequent-ly improved structural strength are comprised of carbon fibers, an amine-terminated poly(arylene sulfide) resin first component which functions to bring about the adhesion improvement and a thermoplastic resin second component selected from the group consisting of poly(arylene sul-fides), polyolefins, polysulfones, polyether sulfones, poly-etherimides, polyetherketones, polyetheretherketones, poly-etherketoneketones, liquid crystal polymers, and mixtures of such thermoplastic resins.
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The amine-terminated poly(arylene sulfide) resin com-ponent brings about improved bonding by way of the amine-terminal groups to the carbon reinforcing fibers while the polymer portio~ in general bonds to the second thermoplastic resin component utilized. In addition to such chemical bonding the amine-terminated poly(arylene sulfide) component induces a surface on the carbon fibers such that the second component thermoplastic resin matrix can spread out thereon and more readily adhere thereto.
The terms "poly(arylene sulfide(s)" and "poly(arylene sulfide) resin(s)" are used herein to broadly designate arylene sulfide polymers whether homopolymers, copolymers, terpolymers and the like, or a blend of such polymers.
Poly(arylene sulfide) resins which are particularly suitable for use in accordance with the present invention are poly(phenylene sulfide) resins and poly(phenylene sul-fide/sulfone) resins.
Poly(phenylene sulfide) resins which are suitable for use in accordance with the present invention are those described in United States Patents No. 3,354,129 issued Nov. 21, 1967; 3,919,177 issued Nov. 11, 1975; 4,038,261 issued July 26, 1977; and 4,656,231 issued April 7, 1987, which patents are incorporated herein by reference. Pre-ferred commercially available poly(phenylene sulfide) resins are those manufactured by Phillips Petroleum Company of Bartlesville, Oklahoma and marketed as RYTOW~ poly(phenylene sulfide) resins having melt flows of from about 10 to about 1000 grams per 10 minutes as determined by ASTM D1238, con-dition 315/5Ø
Poly(phenylene sulfide/sulfone) resins and their produc-tion are described in United States Patent No. 4,016,145 issued Apr. 5, 1977 and United States Patent No. 4,127,713 issued Wov. 28, 1978, which patents are incorporated herein by reference. Preferred commercially available poly(phenyl-ene sulfide/sulfone) resins are those manufactured by Phillips Petroleum Company and marketed as RYTON~S poly(phe-nylene sulfide/sulfone) resins having melt flows of from . .......... ~ - I
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about 0.5 to about 350 grams per 10 minutes as determined by ASTM D1238, condition 343/5Ø
In preparing amine-terminated poly(arylene sulfide) resins, and particularly poly(phenylene sulfide) and poly(phenylene sulfide/sulfone) resins, the basic production method described in the above-referenced patents is utilized wherein a sulfur compound is reacted with a polyhalo-sub-stituted aromatic compound in a polar organic solvent. In addition, an alkali metal carboxylate, e.g., sodium acetate, can be included in the reaction mixture to produce higher molecular weight polymers.
Compounds which have been found useful as a sulfur source in the production method generally include alkali metal sulfides, alkali metal hydrosulfides and hydrogen sul-fides. Suitable alkali metal sulfides include lithium sul-fide, sodium sulfide, potassium sulfide, rubidium sulfide and cesium sulfide. Suitable alkali metal hydrosulfides include lithium hydrosulfide, sodium hydrosulfide, potassium hydrosulfide, rubidium hydrosulfide and cesium hydrosulfide.
Sodium sulfide and sodium hydrosulfide are presently pre-ferred as suitable first sulfur sources. It is often con-venient to employ these first sulfur source compounds as aqueous solutions or dispersions in the process of our invention.
The polyhalo-substituted aromatic compounds which can be employed are compounds wherein the halogen atoms are attached to aromatic ring carbon atoms. Preferably, the polyhalo-substituted aromatic compounds are selected from the group consisting of p-dihalobenzenes having the formula R R
X~ X
~ :
R R
m-dihalobenzenes having the formula R X
X ~ R
~ :
R R

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and o-dihalobenzenes having the formula X~,R

whexein X is a halogen selected fr~m the group consisting of -~
chlorine, bromine and iodine and R is hydrogen or an alkyl radical of 1-4 carbon atoms. For reasons of availability and generally good results it is preferred that dichloroben-zenes be employed with p-dichlorobenzene being especially preferred. Mixtures of suitable polyhalo-substituted aroma-tic compounds can also be employed. ~;
Further, polyhalo-substituted aromatic compounds having more than two halogen substituents per molecule can be employed. These compounds are represented by the formula R'(X)n wherein X is as previously defined, R' is a polyva-lent aromatic radical of 6 to about 16 carbon atoms having a valence n, and n is an integer of 3-6. Generally, the polyhalo-substituted aromatic compounds represented by the ~ ~`
formula R'(x)n when employed according to our invention are optional components utilized in small amounts in admixture with suitable dihalo-substituted aromatic compounds.
Examples of some suitable polyhalo-substituted aromatic compounds include 1,4-dichlorobenzene, 1,3-dichlorobenzene, 1,3,5-trichlorobenzene, 1,2-dichlorobenzene, 1,4-dibromo-benzene, 1,4-diiodobenzene, 1-chloro-4-bromobenzene, l-bromo-4-iodobenzene, 2,5-dichlorotoluene, 2,5-dichloro-p-xylene, l-ethyl-4-isopropyl-2,5-dibromobenzene, 1,2,4,5-te-tramethyl-3,6-dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3-dichloro-5-bromobenzene, 2,4,6-trichlorotoluene, hexachlorobenzene, 2,2',4,4'-tetra-chlorobiphenyl, 2,2',6,6'tetrabromo-3,3',5,5'-tetramethyl-biphenyl, 4,4'-dichlorobiphenyl and the like. ~
Although the amount of polyhalo-substituted aromatic ~`
compound relative to the total of the sulfur source com-pounds can vary over a wide range, generally the amount employed will be in the range of from about 0.5 mole percent excess of aromatic halide to about 10 mole percent excess of aromatic halide relative to the total sulfur source com-pounds. A 2 to 3 mole percent excess is preferred.
Polar organic compounds which can be employed include organic amides, lactams, ureas, sulfones and the like. Ex-amples of suitable polar organic compounds include N-methyl-2-pyrrolidone, N-methylcatrolactam, hexamethylphosphoramide, tetramethylurea, N,~'-ethylene dipyrrolidone, pyrrolidone, caprolactam, N-eth~lcaprolactam, 1,3-dimethyl-2-imidazolidi-none, tetramethylene sulfone, diphenyl sulfone, N-ethyl-2-pyrrolidone, l-methyl-4-isopropyl-2-piperazinone, 1,4-di-methyl-2-piperazinone, and mixtures thereof. For reasons of availability, stability and generally good results, N-methyl-2-pyrrolidone is the preferred polar organic com-pound. The amount of polar organic compound employed can be expressed in terms of a molar ratio of polar organic com-pound to total sulfur source compounds. Thus, this ratio will be about 1.5:1 to about 25:1, preferably about 2:1 to about 8:1.
Although the reaction temperature at which the polymeri-zation is conducted can vary over a wide range, generally it will be about 125C to about 375C, preferably about 175C
to about 350C. The reaction time can vary widely, depend-ing in part on the reaction temperature, but generally will be about 6 minutes to about 72 hours, preferably about 1 hour to about 8 hours. The pressure should be sufficient to maintain the organic components of the reaction mixture substantially in the liquid phase. The arylene sulfide polymers produced can be separated from the reaction mixture by conventional procedures, e.g., by filtration of the poly-mer, followed by washing with water or by dilution of the reaction mixture with water, followed by filtration and water washing of the polymer.
In order to produce amine-terminated poly(arylene sul-fide) resins, an amino-organic thiol compound is added to the polymerization reaction mixture. The addition can be made before polymerization conditions are established, or as the polymerization reaction proceeds. The amine-terminated : :

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poly(arylene sulfide) produced should have a melt flow in the range of from about 10 to about 5000 grams per 10 minutes as determined by ASTM 1238, condition 317/0.36.
The amino-organic thiol compound can be represented by the formula Z-S-R" wherein Z is a halogen-free cyclic amino-organic radical preferably containing a total of about 5 to about 25 carbon atoms. Z can be selected from amino-carbo-cyclic and amino-heterocyclic radicals having 1 to 4 hetero-atoms as cycle members. Said heteroatoms are individually selected from the group consisting of nitrogen, oxygen and sulfur. The halogen-free cyclic amino-organic radical Z can also have O to about 4 substituents selected from the group consisting of alkyl, cycloalkyl, aryl, alkoxy, aryloxy, acyl, aroyl, alkoxycarbonyl, alkanamido, alkylamino, and alkylsulfonyl radicals. The -S-R" portion of the Z-S-R"
compound is attached directly to a carbon atom which is a cycle member of Z.
R" is selected from the group consisting of H and M
where M is a metal selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium and barium. Thus, the amino-organic thiol compound can be employed as the thiol per se or as a metal salt thereof, i.e., a metal thiolate, wherein the metal is selected from the list given above. When a metal thiolate is employed according to our invention, it can be formed in situ from the reaciton of the amino-organic thiol with a suitable metal compound such as a metal oxide, metal hydride or metal hydroxide where the metal is selected from the list given above. Examples of suitable metal compounds for use in the in situ formation of the metal thiolate include lithium hyroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, lithium hydride, sodium hydride, magnesium oxide, calcium oxide, strontium oxide and barium oxide.
Examples of suitable halogen-free cyclic amino-organic radicals Z in the amino-organic thiol compound Z-S-R" in-clude 2- and 4-aminophenyl, 2- and 4'-aminobiphenyl, amino-., ~-. ~ ,. - . , ~ ' , naphthyl and aminopyridyl.
As mentioned above, the amino-organic thiol compound can be added to the polymerization reaction mixture in various ways and at various times. However, it is particularly con-venient to add the amino-organic thiol compound in admixture with a portion of the polar organic compound component that is utilized prior to carrying out the polymerization reac-tion. The amount of amino-organic thiol compound employed can be expressed in terms of a molar ratio of amino-organic thiol compound to inorganic sulfur source used. This ratio is in the range of from about 0.0001:1.00 to about 0.10:1.00. As mentioned above, the amine-terminated poly-mers produced should have a melt flow of from about 10 to about 5000 grams per 10 minutes, and the amount of amino-organic thiol compound used can be varied to obtain such desired melt flow.
Generally, the polymerization reaction is conducted at a temperature in the range of from about 125C to about 375C, preferably about 175C to about 350C. The reaction time can vary widely depending in part on reaction temperature, but generally the time will range from about 6 minutes to about 72 hours, preferably from about 1 to about 8 hours.
The pressure should be sufficient to maintain the organic components of the reaction mixture substantially in the liquid phase. Upon completion of the reaction, the amine-terminated arylene sulfide polymers produced can be separ-ated from the reaction mixture by conventional procedures, e.g., by filtration, followed by washing with water or by diluting the reaction mixture with water, followed by fil-tration and water washing of the polymer.
As will be understood by those skilled in the art, when amine-terminated poly(arylene sulfide/sulfone) resin is pro-duced, the method described above can be used except that dihaloaromatic sulfones are employed in the polymerization reaction. The dihaloaromatic sulfones which can be used are represented by the formula ....

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R"'R"' X' ~ S02~ Z' - SO2~ x~
~"~" R"'~"

wherein X' is selected from the group consisting of fluor-ine, chlorine, bromine and iodine;
Z' is a divalent radical selected from the group consisting of ~" R"' R"' ~ 11 R"' R"' , and ~ (A)n " R"' R"' R"' ~ " R"' m is O or l;
n is O or l;
A is selected from the group consisting of oxygen sulfur, sulfonyl, and C~"2; and each ~" is selected from the group consisting of hydrogen and alkyl radicals having 1 to about 4 carbon atoms, the total number of carbon atoms in all the ~" groups in the molecule being O to about 12.
Examples of some dihaloaromatic sulfones that can be employed include bis(p-fluorophenyl) sulfone, bis(p-chloro-phenyl) sulfone, p-chlorophenyl p'-bromophenyl sulfone, bis(2,5-dipropyl-4-chlorophenyl) sulfone, and the like.
The carbon fibers which are utilized in the composites of the present in~ention can take various forms depending upon the particular method used for producing the composite.
For example, when the composites are injection molded using an injection molding machine, the carbon fibers are chopped.
When the composites are formed by pultrusion methods, long length carbon fibers can be used, but continuous carbon fibers are most preferred. The carbon fibers are in the form of individual rovings or bundles. Woven carbon fiber fabrics can also be used. In whatever form the carbon ' '': ~ : '. : , , -12- 2~3~

fibers take, they are generally present in the composite in an amount in the range of from about 10% to about 80% by weight of the composite.
The second thermoplastic resin component can be and pre-ferably is a poly(arylene sulfide) resin produced as de-scribed above, but without amine termination. Poly(phenyl-ene sulfide) resins or poly(phenylene sulfide/sulfone) resins or mixtures of such resins are particularly pre-ferred. However, other thermoplastic resins such as poly-olefins, polysulfones, polyether sulfones, polyetherimides, polyetherketones, polyetheretherketones, polyetherketone-ketones, liquid crystal polymers, and mixtures of such resins can be used. The various resins can be used indivi-dually, in admixture with each other, or in admixture with poly(arylene sulfide) resins~ Generally, the two thermo-plastic resin components are present in the composites of the present invention in a total amount in the range of from about 20% to about 90% by weight of the composite. Of the total amount of thermoplastic resin utilized in the co.npo site, the amine-terminated poly(arylene sulfide) resin can be included therein in an amount in the range of from about 0.5% to about 99.5% by weight of the total resin. Prefer-ably, the amine-terminated poly(arylene sulfide) resin is present in the total resin utilized in an amount in the range of from about 0.5% to about 50% by weight of the total resin.
As mentioned above, the amine-terminated poly(arylene sulfide) component of the composite can be applied to the carbon fibers prior to impregnating the carbon fibers with the second thermoplastic resin component. When this tech-nique is used, however, the amount of amine-terminated poly(arylene sulfide) resin generally cannot be more than about 0.5% by weight of the formed composite because higher quantities on the fibers causP them to stick together. A
more preferred technique is to combine the amine-terminated poly(arylene sulfide) first component resin with the second component resin in the greater amounts described above.
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While various methods of producing the improved compo~
sites of the present invention can be utilized, such methods basically comprise the steps of mixing carbon fibers with thermoplastic resin comprised of an amine-terminated poly(arylene sulfide) resin first component and a thermo-plastic resin second component selected from the group con-sisting of poly(arylene sulfide) resin, polyolefin resin, polysulfones, polyether sulfones, polyetherimides, poly-etherketones, polyetheretherketones, polyetherketoneketones, liquid crystal polymers, and mixtures of such resins; fol-lowed by the step of consolidating the mixture into a formed composite.
The preferred method of producing composites of this invention utilizes the pultrusion technique wherein a roving of carbon fibers is pulled through a thermoplastic resin bath whereby the roving is impregnated with the thermoplas-tic resin followed by pulling the impregnated roving through a heated forming die to consolidate the thermoplastic resin matrix and carbon fibers into a composite. Such a pultru-sion technique for producing such a composite is described in U.S. Patent No. 4,680,224 to O'Connor, which patent is incorporated herein by reference. The thermoplastic resin bath can be a mixture of the amine terminated poly(arylene sulfide) resin first component and thermoplastic resin second component, or separate thermoplastic resin baths can be used whereby the roving is first pulled through a resin bath of the amine-terminated polymer first component fol-lowed by being pulled through a resin bath containing the thermoplastic resin second component. The terms "consoli-date" and "consolidating" are used herein to mean forming the resin mixture and carbon fibers in the presence of heat into a composite of desired shape having the carbon fibers disposed within a resin matrix.
In order to further illustrate the improved composites and methods of the present invention, the following examples are presented. The particular reactants, conditions, ratios and the like as well as the ingredients and components used : ~. , - .
- : : . , :, .

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are intended to be illustrative of the invention and not limiting thereof.

Example 1 An amine-terminated poly(phenylene sulfide) resin was prepared by reacting 6 moles of sodium hydrosulfide, 6.15 moles of para-dichlorobenzene and 0.04538 mole of 4-amino-benzene thiol (0.76 mole % based on sulfur) in 1~.56 moles of ~-methyl-2-pyrrolidone and 6.035 moles of sodium hydrox-ide. The polymerization reaction was carried out for suc-cessive l-hour periods while stirring at 600 rpm at 235C
the first hour, 265C the second hour and 280C the third hour. The polymers so produced had a melt flow of 87.7 grams/10 minutes as determined by ASTM 1238, condition 317/0.36, using a 1.250 inch long orifice.
Composites were formed using carbon fibers produced by Hercules, Inc. of Wilmington, Delaware under the trade designation AS4-12K. Such carbon fibers which included a sizing applied by Hercules, Inc. were used (designated as G-sized fibers) as were the same carbon fibers without sizing.
Carbon fiber rovings were pulled from creels through a resin bath containing an agitated aqueous slurry of approximately 87~ by weight Phillips Petroleum Company RYTON~ poly(phenyl-ene sulfide) resin (PRO9) and 13% by weight of the amine-terminated poly(phenylene sulfide) polymers produced as described above. The resulting impregnated roving was pulled through a drier at a temperature of 740F, through an -~
over-and-under die and then through a heated forming die at a temperature of 628F. The resulting consolidated compo~
site was cut into sections which were pressed into laminates for testing.
Both laminates formed of the carbon fibers including sizing and those formed of carbon fibers without sizing were tested for strength properties. That is, longitudinal ten-sile strength was determined in accordance with ASTM D-638, transverse tensile strength was determined in accordance -~-with ASTM D-638, compressive strength in accordance with ~;~
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ASTM D3410 (ITRII method) and flexural strength in accor-dance with ASTM D-790. The results of such strength tests are shown in Table I below.

TABLE I

~vg. LongitudinalAvg. Transverse Fiber Type/Composite Tensile (KSI) Tensile (KSI) G-sized 232.67 2.31 No Sizing 260.90 4.42 Avg. Compressive Avg. Flexural (KSI) (KSI) G-sized 123.30 216.22 No Sizing 135.60 260.59 The transverse tensile and compressive strengths of the laminates are the best indicators of the adhesion between the carbon fibers and the thermoplastic matrices of the laminates. From the Table I results, it can be seen that laminates produced in accordance with the present invention using carbon fibers without sizing had the best adhesion.

Example 2 This Example follows the procedures of Example 1 in exa-mining commercially si~ed and non-sized carbon fibers, with the exception that the impregnated non-sized rovings were dried at 760F as opposed to 780F. Strength testing proce-dures were also identical to Example 1. The preparation of amine-terminated poly(phenylene sulfide) resin was the same as described in Example 1 with the exception that the mole percent of the 4-aminobenzene thiol compound used in the process was increased to 3.78 mole percent (based on sulfur) producing polymers having a melt flow of 2358 grams/10 minutes.
Results from the strength testing of the laminates pro-duced are shown in Table II below.

.. : .. . .. - .

~ V7 TABLE II

Avg. LongitudinalAvg. Transverse Fiber Type/Comp~site Tensile (KSI) Tensile (KSI) G-sized 241.10 2.55 No Sizing 226.33 3.29 Avg. Compressive Avg. Flexural (KSI) (KSI) G-sized 141.03 224.62 No Sizing 126.30 235.95 Example 3 A different amino-organic thiol compound, i.e., 2-amino-benzene thiol, was used in the preparation of the amine-ter-minated poly(phenylene sulfide) resin in this Example, but the same quantity as in Example 2 was used, i.e., 3.78 mole percent (based on sulfur). The fiber ccntained no sizing.
The production of laminates and their testing were the same as Example 1. The terminated polymers had a melt flow of 1838 grams/10 minutes. The laminates prepared had an aver-age longitudinal tensile strength of 225.50 KSI, an average transverse tensile strength of 2.15 KSI, an average compres-sive strength of 137.07 KSI and an average flexural strength of 229.48 KSI.

Example 4 In this Example the 2-aminobenzene thiol of Example 3 was used in the quantity of Example 1, namely 0.76 mole p~r-cent (based on sulfur). The fiber contained no sizing. The preparation of laminates and their testing were the same as Example 1. The resulting terminated polymers had a melt flow of 64.3 grams/10 minutes. The laminates produced had an average longitudinal tensile strength of 252~77 KSI, an average compressive strength of 133.70 RSI, and an average flexural strength of 223.52 KSI. The average transverse tensile strength was not measured.
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Example 5 As a control, laminates were formed using the procedures described in Example 1 from composites including G-sized carbon fibers and resin matrices of RYTON~ poly(phenylene sulfide) (PRo9) containing no amine-terminated polymers.
Strength testing of these laminates gave an average longitu-dinal tensile strength of 255.63 KSI, an average transverse tensile strength of 4.03 KSI, an average longitudinal com-pressive strength of 113.87 KSI, and an average longitudinal flexural strength of 269.70 KSI.

It can be seen from the Examples above that the best results, using the criteria of improved transverse tensile and compressive strengths, are obtained from carbon fibers that have not been previously sized as compared to those that have been sized. Also, the examples show that the use of amine-terminated poly(phenylene sulfide) in the resin matrix in accordanc~ with the present invention improves the adhesion between the resin matrix and carbon fibers.
Thus, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned above as well as those inherent therein. While preferred embodiments of the invention have been described for the purpose of this disclosure, changes in the components and the performance of steps can be made by those skilled in the , art, which changes are encompassed within the spirit of this invention as defined by the appended claims.
What is claimed is:

:.

Claims

1. A high strength thermoplastic resin/carbon fiber composite comprising:
carbon fibers;
an amine-terminated poly(arylene sulfide) first resin component; and a second resin component selected from the group consisting of poly(arylene sulfides), polyole-fins, polysulfones, polyether sulfones, poly-etherimides, polyetherketones, polyetherether-ketones, polyetherketoneketones, liquid crys-tal polymers, and mixtures of such resins.

2. The composite of claim 1 wherein said carbon fibers are present in an amount in the range of from about 10% to about 80% by weight of the total resin in said composite.

3. The composite of claim 2 wherein said amine-termin-ated poly(arylene sulfide) first resin component is present in an amount in the range of from about 0.5% to about 99.5%
by weight of the thermoplastic resin of said composite.

4. The composite of claim 3 wherein said amine-termin-ated poly(arylene sulfide) resin has a melt flow in the range of from about 10 to about 5000 grams per 10 minutes as determined by ASTM D1238, condition 317/0.36, using a 1.250 inch long orifice.

5. The composite of claim 3 wherein said amine-termin-ated poly(arylene sulfide) resin is an amine-terminated poly(phenylene sulfide) resin.

6. The composite of claim 3 wherein said amine-termin-ated poly(arylene sulfide) resin is an amine-terminated poly(phenylene sulfide/sulfone) resin.

7. The composite of claim 3 wherein said second resin component is one of or a mixture of poly(arylene sulfide) resins.

8. The composite of claim 5 wherein said second resin component is selected from poly(phenylene sulfide) resin, poly(phenylene sulfide/sulfone) resin and mixtures of such resins.

9. A method of producing a high strength thermoplastic resin/carbon fiber composite comprising the steps of:
mixing carbon fibers with an amine-terminated poly(arylene sulfide) first resin component and a second resin component selected from the group consisting of poly(arylene sulfides), polyolefins, polysulfones, polyether sulfones, polyetherimides, polyetherketones, polyether-etherketones, polyetherketoneketones, liquid crystal polymers, and mixtures of such resins, and consolidating said mixture into a composite of car-bon fibers in a resin matrix.

10. The method of claim 9 wherein said carbon fibers are present in said mixture in an amount in the range of from about 10% to about 80% by weight thereof.

11. The method of claim 10 wherein said amine-termin-ated poly(arylene sulfide) first resin component is present in said mixture an amount in the range of from about 0.5% to about 99.5% by weight of the total of said first and second resin components.

12. The method of claim 11 wherein said amine-termin-ated poly(arylene sulfide) resin has a melt flow in the range of from about 10 to about 5000 grams per 10 minutes as determined by ASTM D1238, condition 317/0.36, using a 1.250 inch long orifice.

13. The method of claim 11 wherein said amine-termin-ated poly(arylene sulfide) resin is an amine-terminated poly(phenylene sulfide) resin.

14. The method of claim 11 wherein said amine-termin-ated poly(arylene sulfide) resin is an amine-terminated poly(phenylene sulfide/sulfone) resin.

15. The method of claim 11 wherein said second resin component is one of or a mixture of poly(arylene sulfide) resins.

16. The method of claim 13 wherein said second resin component is selected from poly(phenylene sulfide) resin, poly(phenylene sulfide/sulfone) resin and mixtures of such resins.

17. A high strength thermoplastic resin/carbon fiber composite produced in accordance with the method of claim 9.

18. A high strength thermoplastic resin/carbon fiber composite produced in accordance with the method of claim 10.

19. A high strength thermoplastic resin/carbon fiber composite produced in accordance with the method of claim 11.

20. A high strength thermoplastic resin/carbon fiber composite produced in accordance with the method of claim 13.

21. A high strength thermoplastic resin/carbon fiber composite produced in accordance with the method of claim 16.

22. A method of producing a high strength thermoplastic resin/carbon fiber composite comprising the steps of:
impregnating a continuous carbon fiber roving with a thermoplastic resin mixture comprised of an amine terminated poly(arylene sulfide) first resin component and a second resin component selected from the group consisting of poly(arylene sulfides), polyolefins, poly-sulfones, polyether sulfones, polyetherimides, polyetherketones, polyetheretherketones, polyetherketoneketones, liquid crystal poly-mers, and mixtures of such resins; and pulling said impregnated roving through a heated forming die whereby said impregnated roving is consolidated into a composite.

23. The method of claim 22 wherein said carbon fibers are present in said impregnated roving in an amount in the range of from about 50% to about 80% by weight of said impregnated roving.

24. The method of claim 22 wherein said amine-termin-ated poly(arylene sulfide) first resin component is present in said impregnated roving in an amount in the range of from about 0.5% to about 99.5% by weight of said thermoplastic resin mixture.

25. The method of claim 24 wherein said amine-termin-ated poly(arylene sulfide) resin is an amine-terminated poly(phenylene sulfide) resin.

26. The method of claim 24 wherein said amine-termin-ated poly(arylene sulfide) resin is an amine-terminated poly(phenylene sulfide/sulfone) resin.

27. The method of claim 24 wherein said second resin component is one of or a mixture of poly(arylene sulfide) resins.

28. The method of claim 25 wherein said second resin component is selected from poly(phenylene sulfide) resin, poly(phenylene sulfide/sulfone) resin and mixtures of such resins.

29. The method of claim 24 wherein said step of impreg-nating said continuous carbon fiber roving with said resin mixture comprises pulling said roving through a bath con-taining said resin mixture.

30. The method of claim 24 wherein said step of impreg-nating said continuous carbon fiber roving with said resin mixture comprises:
pulling said roving through a bath containing said amine-terminated poly(arylene sulfide) resin first component; and then pulling said roving through a second bath con-taining said second component resin.

31. The method of claim 29 or 30 wherein said amine-terminated first resin component is an amine-terminated poly(phenylene sulfide) resin and said second resin com-ponent is a poly(phenylene sulfide) resin.

32. A high strength thermoplastic resin/carbon fiber composite formed in accordance with the method of claim 22.

33. A high strength thermoplastic resin/carbon fiber composite formed in accordance with the method of claim 24.

34. A high strength thermoplastic resin/carbon fiber composite formed in accordance with the method of claim 28.

35. A high strength thermoplastic resin/carbon fiber composite formed in accordance with the method of claim 30.