High strength thermoplastic resin/carbon fiber composites and methods

High strength thermoplastic resin/carbon fiber composites 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, polyether sulfones, polyetherimides, polyetherketones, polyethertherketones, polyetherketoneketones, liquid crystal polymers, and mixtures of such resins.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to poly(arylene sulfide) composites, and 
more particularly, to poly(arylene sulfide)/carbon fiber composites having 
improved adhesion between the resin matrix and the carbon fibers in the 
composite. 
2. Description of the Prior Art 
It has long been appreciated that good adhesion between the resin matrix 
and the reinforcing fibers utilized in composite material is necessary. 
The usual means employed for enhancing adhesion between the fibers and the 
resin matrix has been to use a sizing composition to 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 different 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 
thermoplastic 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). 
Well known poly(arylene sulfides) are poly(phenylene sulfide) and 
poly(phenylene sulfide/sulfone) which are commercially available under the 
trademark RYTON.RTM. from the Phillips Petroleum Company, Bartlesville, 
Okla. Such resins are particularly suitable for use in composites because 
of their excellent rigidity and heat and electrical resistance as compared 
to other thermoplastic 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 
thermoplastics 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 compositions that have been traditionally 
employed in the thermoset 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 carbon fibers as well as for the composites 
so produced, particularly 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 composites. 
The composites are basically each comprised of carbon fibers, an 
amine-terminated poly(arylene sulfide) first component and a second 
thermoplastic resin component selected from the group consisting of 
poly(arylene sulfides), polyolefins, polysulfones, polyether sulfones, 
polyetherimides, polyetherketones, polyetheretherketones, 
polyetherketoneketones, 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 is 
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 polymerization. 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, condition 317/0.36, using a 
1.250 inch long orifice), and function 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 
composite results when the amine-terminated poly(arylene sulfide) 
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 utilized 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 utilized for combining the carbon 
fibers and thermoplastic resin components and forming a composite 
therefrom, including 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 component. The fiber roving is impregnated with 
the resin mixture 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 the 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 provision 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 preferred 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 consequently 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 sulfides), polyolefins, polysulfones, polyether sulfones, 
polyetherimides, etherketoneketones, liquid crystal polymers, and mixtures 
of such thermoplastic resins. 
The amine-terminated poly(arylene sulfide) resin component brings about 
improved bonding by way of the amineterminal groups to the carbon 
reinforcing fibers while the polymer portion 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 sulfide/sulfone) resins. 
Poly(phenylene sulfide) resins which are suitable for use in accordance 
with the present invention are those described in U.S. Pat. Nos. 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 Apr. 7, 1987, which patents are 
incorporated herein by reference. Preferred commercially available 
poly(phenylene sulfide) resins are those manufactured by Phillips 
Petroleum Company of Bartlesville, Okla. and marketed as RYTON.RTM. 
poly(phenylene sulfide) resins having melt flows of from about 10 to about 
1000 grams per 10 minutes as determined by ASTM D1238, condition 315/5.0. 
Poly(phenylene sulfide/sulfone) resins and their production are described 
in U.S. Pat. No. 4,016,145 issued Apr. 5, 1977 and U.S. Pat. No. 4,127,713 
issued Nov. 28, 1978, which patents are incorporated herein by reference. 
Preferred commercially available poly(phenylene sulfide/sulfone) resins 
are those manufactured by Phillips Petroleum Company and marketed as 
RYTON.RTM.S poly(phenylene sulfide/sulfone) resins having melt flows of 
from about 0.5 to about 350 grams per 10 minutes as determined by ASTM 
D1238, condition 343/5.0. 
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-substituted 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 sulfides. Suitable alkali metal sulfides include lithium 
sulfide, 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 
preferred as suitable first sulfur sources. It is often convenient 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 
##STR1## 
m-dihalobenzenes having the formula 
##STR2## 
and o-dihalobenzenes having the formula 
##STR3## 
wherein X is a halogen selected from 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 dichlorobenzenes be employed with p-dichlorobenzene being 
especially preferred. Mixtures of suitable polyhalo-substituted aromatic 
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).sub.n wherein X is as previously defined, 
R' is a polyvalent 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).sub.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-dibromobenzene, 1,4-diiodobenzene, 
1-chloro-4-bromobenzene, 1-bromo-4-iodobenzene, 2,5-dichlorotoluene, 
2,5-dichloro-p-xylene, 1-ethyl-4-isopropyl-2,5-dibromobenzene, 
1,2,4,5-tetramethyl-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'-tetrachlorobiphenyl, 
2,2',6,6'tetrabromo-3,3',5,5'-tetramethylbiphenyl, 4,4'-dichlorobiphenyl 
and the like. 
Although the amount of polyhalo-substituted aromatic compound relative to 
the total of the sulfur source compounds 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 compounds. 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. Examples of suitable polar organic 
compounds include N-methyl-2-pyrrolidone, N-methylcatrolactam, 
hexamethylphosphoramide, tetramethylurea, N,N'-ethylene dipyrrolidone, 
pyrrolidone, caprolactam, N-ethylcaprolactam, 
1,3-dimethyl-2-imidazolidinone, tetramethylene sulfone, diphenyl sulfone, 
N-ethyl-2-pyrrolidone, 1-methyl-4-isopropyl-2-piperazinone, 
1,4-dimethyl-2-piperazinone, and mixtures thereof. For reasons of 
availability, stability and generally good results, N-methyl-2-pyrrolidone 
is the preferred polar organic compound. The amount of polar organic 
compound employed can be expressed in terms of a molar ratio of polar 
organic compound 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 polymerization is conducted 
can vary over a wide range, generally it will be about 125.degree. C. to 
about 375.degree. C., preferably about 175.degree. C. to about 350.degree. 
C. The reaction time can vary widely, depending 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 polymer, 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 sulfide) 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 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 aminoorganic radical preferably 
containing a total of about 5 to about 25 carbon atoms. Z can be selected 
from amino-carbocyclic and amino-heterocyclic radicals having 1 to 4 
heteroatoms 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 0 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 reaction 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 hydroxide, 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" include 2- and 4-aminophenyl, 2- and 
4'-aminobiphenyl, aminonaphthyl 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 convenient 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 
reaction. 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 
polymers produced should have a melt flow of from about 10 to about 5000 
grams per 10 minutes, and the amount of aminoorganic 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 125.degree. C. to about 375.degree. C., preferably 
about 175.degree. C. to about 350.degree. C. 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 separated 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 
filtration 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 produced, 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 
##STR4## 
wherein 
X' is selected from the group consisting of fluorine, chlorine, bromine and 
iodine; 
Z' is a divalent radical selected from the group consisting of 
##STR5## 
m is 0 or 1; 
n is 0 or 1; 
A is selected from the group consisting of oxygen sulfur, sulfonyl, and 
CR'".sub.2 ; and 
each R'" 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 R'" groups in the molecule being 0 to about 12. 
Examples of some dihaloaromatic sulfones that can be employed include 
bis(p-fluorophenyl) sulfone, bis(p-chlorophenyl) 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 
invention 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 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 preferably is a 
poly(arylene sulfide) resin produced as described above, but without amine 
termination. Poly(phenylene sulfide) resins or poly(phenylene 
sulfide/sulfone) resins or mixtures of such resins are particularly 
preferred. However, other thermoplastic resins such as polyolefins, 
polysulfones, polyether sulfones, polyetherimides, polyetherketones, 
polyetheretherketones, polyetherketoneketones, liquid crystal polymers, 
and mixtures of such resins can be used. The various resins can be used 
individually, in admixture with each other, or in admixture with 
poly(arylene sulfide) resins. Generally, the two thermoplastic 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 
composite, 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. Preferably, 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 
technique 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 cause 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. 
While various methods of producing the improved composites 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 
thermoplastic resin second component selected from the group consisting of 
poly(arylene sulfide) resin, polyolefin resin, polysulfones, polyether 
sulfones, polyetherimides, polyetherketones, polyetheretherketones, 
polyetherketoneketones, liquid crystal polymers, and mixtures of such 
resins; followed 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 
thermoplastic 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 pultrusion technique for producing 
such a composite is described in U.S. Pat. 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 
followed by being pulled through a resin bath containing the thermoplastic 
resin second component. The terms "consolidate" 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 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-aminobenzene thiol (0.76 mole % based on sulfur) in 
16.56 moles of N-methyl-2-pyrrolidone and 6.035 moles of sodium hydroxide. 
The polymerization reaction was carried out for successive 1-hour periods 
while stirring at 600 rpm at 235.degree. C. the first hour, 265.degree. C. 
the second hour and 280.degree. C. 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, Del. 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.RTM. poly(phenylene 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 740.degree. F., through an over-and-under die 
and then through a heated forming die at a temperature of 628.degree. F. 
The resulting consolidated composite 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 tensile 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 ASTM 
D3410 (ITRII method) and flexural strength in accordance with ASTM D-790. 
The results of such strength tests are shown in Table I below. 
TABLE I 
______________________________________ 
Avg. Longitudinal 
Avg. Transverse 
Fiber Type/Composite 
Tensile (KSI) Tensile (KSI) 
______________________________________ 
G-sizing 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 examining commercially 
sized and non-sized carbon fibers, with the exception that the impregnated 
non-sized rovings were dried at 760.degree. F. as opposed to 780.degree. 
F. Strength testing procedures 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 produced are shown in 
Table II below. 
TABLE II 
______________________________________ 
Avg. Longitudinal 
Avg. Transverse 
Fiber Type/Composite 
Tensile (KSI) Tensile (KSI) 
______________________________________ 
G-sizing 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-aminobenzene thiol, was 
used in the preparation of the amine-terminated 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 contained 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 average longitudinal tensile strength of 225.50 
KSI, an average transverse tensile strength of 2.15 KSI, an average 
compressive strength of 137.07 KSI and an average flexural strength of 
229.48 KSI. 
EXAMPLE 4 
Example the 2-aminobenzene thiol of Example 3 was used in the quantity of 
Example 1, namely 0.76 mole percent (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 
KSI, and an average flexural strength of 223.52 KSI. The average 
transverse tensile strength was not measured. 
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.RTM. poly(phenylene sulfide) (PRO9) containing no 
amine-terminated polymers. Strength testing of these laminates gave an 
average longitudinal tensile strength of 255.63 KSI, an average transverse 
tensile strength of 4.03 KSI, an average longitudinal compressive 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 
accordance 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.