Materials and processes for fabricating formed composite articles and use in shoe arch

A strong, lightweight composite material having beneficial flexing characteristics is made using a unique reinforcement material. The reinforcement material comprises a fabric incorporating glass rovings with graphite tows in an architectural combination that retains the properties of both materials. Composite structures made using this reinforcement material with a thermosetting or thermoplastic matrix are extremely lightweight, with desirable anisotropic flexing properties. The finished composite structure is extremely useful as an arch support in a shoe to absorb and distribute the forces generated by walking. In distributing forces on the foot such a support will provide the desired stiffness along the longitudinal axis while allowing increased flexibility along the transverse axis.

BACKGROUND OF THE INVENTION 
1. Field of The Invention 
The present invention relates to thermoplastic or thermosetting resin 
composite material incorporating an improved reinforcement fabric. More 
particularly, the invention relates to the use of an improved glass and 
graphite composite reinforcement to impart anisotropic properties a shaped 
composite structure. The resulting composite structure, such as an arch 
support for a shoe, is strong, lightweight and resilient with improved 
flexing properties. 
2. Description of Related Art 
During the past several years many researchers working with structural 
materials have focused on developing strong lightweight articles that are 
durable, cost effective and easy to fabricate. Such materials would be in 
great demand for applications ranging from aircraft construction to 
athletic equipment. For example, structural materials having high 
durability and significant strength to weight ratios are necessary for 
many advanced aerospace applications. Similarly, low weight resilient 
materials with shock absorbing flexibility are continually in demand for 
fabricating equipment and structural supports. Traditional fabrication 
materials such as metal alloys and plastics have not proved satisfactory 
in providing the desired combination of properties. For instance, if 
acrylics or other plastics are used to form articles they must sacrifice 
low weight and flexibility in order to achieve the strength necessary for 
many applications. 
The search for substances having these desirable properties has resulted in 
the extensive development of composite materials. Composite materials are 
materials in which two or more distinct substances such as metals, glass, 
ceramics, or polymers are combined, with or without chemical reaction, to 
produce a material with structural or functional characteristics different 
from the individual constituents. The constituents retain their individual 
characteristics and are distinguishable on a microscopic scale. Typically 
one constituent is classified as the reinforcement and the other as the 
matrix. The reinforcement provides the strength or stiffness in the 
composite. The matrix binds the reinforcement together and contributes to 
the distribution of the load. 
To a greater or lesser extent composite materials usually require 
relatively more effort for their fabrication. Yet despite the 
complications inherent in their preparation, composite materials represent 
an interesting alternative to metals whenever there is a demand for great 
strength with minimal weight. Other than metal alloys, this is only 
attainable with materials having high tensile strength and low density. 
Classes of materials commonly used for reinforcements are glasses, metals, 
polymers, ceramics and graphite. The reinforcement can be in many forms, 
such as continuous fibers or filaments, chopped fibers, woven fibers, 
particles or ribbons. The criteria for selecting the type and form of 
reinforcement will vary in accordance with the design requirement for the 
composite. However, criteria for a generally desirable reinforcement 
include high strength, high modulus, low weight, low cost, ease of 
fabrication and environmental resistance. The properties of the composite 
material are derived from matrix characteristics in combination with the 
inherent properties of the reinforcement material along with the form and 
amount of reinforcement used. Composite materials typically incorporate 
several layers or laminae of reinforcing material into a composite 
structure or laminate. 
The prior art contains numerous examples of different materials having 
these criteria to a greater or lesser extent being employed as 
reinforcements in composite structures. Those reinforcement materials 
which have generally favorable properties confer elastic rigidity, tensile 
and fatigue strength, as well as appropriate electrical and magnetic 
properties to the resulting composite. The basic problem with current 
composite reinforcement materials is that they fail to provide all the 
desired attributes simultaneously. Thus the properties of impact 
absorption, variable flexibility, ease of fabrication, cost and durability 
are often mutually exclusive in existing composite materials. 
Though an endless number of reinforcement materials may be employed to 
satisfy different structural or functional requirements, relatively few 
are extensively used. Due to their low cost and reproducibly good 
properties, glass fibers have become one of the principal reinforcement 
materials in use today. The glass fibers are prepared by melting raw 
materials and extruding the molten glass to yield an amorphous, 
anisotropic product. Along with their low cost, glass fibers generally 
have a high strength to weight ratio but their moduli are significantly 
lower than those of most other high performance fibers. Therefore they may 
be used to fabricate materials which are relatively flexible. Several 
types of specialized glass with selected properties have been developed 
for use in composite materials. Of the glass fibers typically found in 
reinforcing materials, E-glass is the most common grade and has the lowest 
cost per unit. 
Carbon fibers are currently the predominant high strength, high modulus 
reinforcing fiber used in the manufacture of advanced composite materials. 
Production methodology can increase the extent of crystallite orientation 
parallel to the carbon fiber axis and thus increase the fiber modulus. 
Because of the high degree of internal structure orientation, the graphite 
fibers are strongly anisotropic. Their transverse tensile strength and 
sheer moduli are usually an order of magnitude lower than the axis 
modulus. Although carbon fibers have been produced with diameters in 
excess of 25 .mu.m, most fibers are on the order of 6-8 .mu.m in diameter. 
With such small sizes the carbon filaments must be handled as tows rather 
than individual microfilaments. Commercially available tows contain 
anywhere from 1,000 to 60,000 fibers per yarn. 
As indicated previously a lamina is defined as one layer or ply of 
reinforcement material embedded in the matrix. The properties of each 
lamina are determined by the properties of its constituents as well as the 
form, orientation and amount of reinforcement used. In general laminae 
employing long continuous fibers running parallel to each other are 
stronger than those using short, randomly oriented fibers. Such laminae 
are anisotropic in that they are stronger and stiffer along the 
longitudinal axis running parallel to the fibers than the transverse axis 
running perpendicular to the fibers. In addition, laminae incorporating 
woven reinforcements are generally stronger along the transverse axis than 
those with unwoven parallel fiber reinforcements. 
The prior art teaches that the laminae may be combined to form laminate 
structures having properties determined by the orientation of the 
reinforcement material in the laminae. To compensate for the low 
transverse properties of the unidirectional material, laminae may be cross 
plied so the fibers are angled relative to each other. This tends to give 
structures with improved transverse properties but at the expense of 
poorer longitudinal properties. Furthermore the in-plane shear strength is 
not significantly improved over that of unidirectional structures. Thus if 
the laminate is not constructed so it is balanced and symmetric, it will 
twist or bend when in-plane loads are applied. The laminate may also 
extend or contract when bending loads are applied. 
Despite these limitations, thermosetting laminate materials have long been 
used to provide complex shapes in articles of manufacture. For example 
U.S. Pat. No. 4,439,934 discloses the use of layered materials to form a 
laminate orthotic insert. The manufacturing process consists of 
laboriously combining layers of fibers at different angles to provide the 
strength and flexibility required by the article. Labor intensive, this 
fabrication method is highly susceptible to manufacturing defects. 
Construction of the layered article is done on a cast and the whole 
combination is thermally set to fix the configuration. The resulting 
insert is relatively thick and heavy with little flexibility for the 
comfort of the user. 
Another example of using a multilayer laminate system may be found in U.S. 
Pat. No. 4,688,338. This patent teaches a laminated structure providing a 
greater resistance to bending moments along the longitudinal axis and less 
resistance to bending along the transverse axis. Yet these beneficial 
properties are imparted by the interaction of separate, resin impregnated 
laminae having parallel reinforcement fibers embedded in the matrix. The 
anisotropic flexibility is imposed solely through the interaction of 
different layers having the parallel reinforcement fibers oriented at 
specific angles relative to each other. There is no teaching that one 
lamina could retain this anisotropic flexibility through the use of a 
fabric reinforcement layer. 
In addition to the reinforcement materials, the other major component of 
any composite material is the matrix. The matrix binds the reinforcement 
together and enhances the distribution of the applied load within the 
composite. Polymeric materials are widely used as matrix materials. The 
two general types of polymers which are generally employed in composite 
materials may be classified as thermosetting and thermoplastic. The 
principal differences between them is the degree of crosslinking and 
response to elevated temperature. Thermosetting resins or polymers are 
extensively crosslinked and undergo irreversible changes when heated or 
reacted with a selected catalyst or a curing agent. In contrast 
thermoplastic materials are generally not crosslinked and soften as they 
are heated. After being exposed to heat they return to their original 
condition when cooled below their melt temperature. 
Thermosetting resins or thermosets are those resins which, in the presence 
of a catalyst, heat radiation and/or pressure undergo an irreversible 
chemical reaction or cure. Prior to cure, thermosets may be liquid or made 
to flow under pressure and heat to any desired form. Once cured they 
cannot be returned to the uncured state and can no longer flow. One of the 
most common types of thermosetting materials are epoxy resins which are 
characterized by the presence of a three membered cyclic ether root 
commonly referred to as an epoxy group, 1,2-epoxide or oxirane. They have 
gained wide acceptance in composite materials because of their exceptional 
combination of properties such as toughness, adhesion, chemical 
resistance, and superior electrical characteristics. When combined with 
their relative ease of handling and processing as well as low unit cost, 
they make up the single most important matrix material. 
In general epoxy resins can be cured by reaction with suitable, 
polyfunctional curing agents such as amines. The qualities of the curing 
agents in polymerization are governed by the structure and choice of 
components. For example, aliphatic amines allow ambient temperature curing 
whereas slow reacting, aromatic amines, require a higher temperature to 
cure. By varying and combining these curing agents, favorable production 
properties can be realized. 
Thermoplastic systems have advantages over some of the thermosets in that 
no chemical reactions which cause release of gas products or excess 
thermal heat are involved. Processing is limited only by the time needed 
to heat, shape, and cool the structure. In addition they are generally 
more ductile and tougher than thermosets. On the other hand solvent 
resistance and heat resistance are not likely to be as good as with 
thermosets. Common thermoplastic materials include polyolefins, vinyls, 
polyamides, acrylics, polyesters, and polysulfones. 
There are many processes for the fabrication of both thermosetting and 
thermoplastic composites. Such processes may be generally classified as 
open molding and closed molding. Open molds are one piece and use low 
pressure while closed molds are two piece and usually involve higher 
pressures. Closed molding techniques include matched die molding, 
injection molding, and continuous laminating. Finishing of the materials 
generally presents no major problems; the appropriate technology is both 
proven and cost effective. Rather, it is the preparation of composites in 
suitable form that tends to be costly. 
Accordingly it is an object of this invention to provide an anisotropic 
reinforcement fabric which may be used in the fabrication of sturdy, 
lightweight, flexible composite structures. 
Further it is an object of this invention to provide a sturdy lightweight 
composite material which may be easily formed into complex shapes. 
In addition it is an object of the present invention to provide a process 
for the fabrication of sturdy, lightweight composite articles. 
In particular it is an object of the present invention to form lightweight 
composite arch supports for use in shoes. 
SUMMARY OF THE INVENTION 
The present invention provides for a graphite and glass fabric reinforced 
composite material which overcomes various difficulties inherent in prior 
art thermoplastic or thermosetting laminate materials. Specifically, the 
composite materials of the present invention are thin, strong, durable, 
and relatively light. Further, the composite structures disclosed herein 
have anisotropic flexibility which may be used in structure designs. For 
instance the composite material may be shaped to form an impact absorbing 
arch support for a shoe. In addition, these composite materials are 
inexpensively and easily fabricated into contoured structures using the 
process disclosed herein. The basic single ply structure may also be 
selectively reinforced to increase the strength of the article without 
greatly increasing its weight. 
In general, the formed composite materials of the present invention are 
fabricated by: providing a reinforcement material, impregnating the 
reinforcement material with a suitable thermosetting or thermoplastic 
resin, and forming the desired composite structure with pressure and heat. 
Specifically, the novel reinforcement material used is a fabric that 
combines glass rovings with graphite tows in an architectural combination 
that results in a fabric which retains the distinctive properties of the 
glass and the graphite. More particularly, the woven fabric is prepared 
having a graphite fiber warp and glass roving fill. The construction of 
the woven fabric contributes to a final formed composite piece that is 
relatively stiff in the longitudinal direction parallel to the carbon 
fibers while retaining the desired flexibility in the lateral direction. 
The composite material may be made using either a thermosetting or 
thermoplastic resin to form the matrix. Preferred resins for impregnating 
the reinforcement material are low viscosity epoxies polyesters, 
polyurethanes, and acrylics which provide suitable working time and cure 
temperatures. However, other resins may be employed, depending on the 
intended use of the composite materials. Thermoplastics, which are 
available in film form with a melting range below 600.degree. F. are also 
suitable for use in the present invention. Some of the thermoplastic 
materials which may be used include polycarbonates, polyetherimides, 
acrylics, and polyurethanes. 
The shape of the finished composite piece is formed using a press molding 
technique with the male mold side being hard tooling such as aluminum or 
steel and the female side being soft tooling such as silicone or urethane 
sheet pressure bags. In order to mold the composite structure, strips of 
impregnated reinforcement material are cut corresponding to the mold width 
and a length equivalent to the length of an arbitrary number of ganged 
molds. The strip is placed between the two mold faces, pressed at the 
desired temperature for the desired period of time, and then removed from 
the mold surfaces. The final desired part is cut from the molded product 
using conventional methods such as water jet cutting. 
Further objects, features, and advantages of the present invention will 
become apparent to those skilled in the art from a consideration of the 
following detailed description when considered in combination with the 
following drawings.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
The present invention involves the discovery that strong lightweight 
composite materials can be fabricated using a glass and graphite 
reinforcement fabric. In a broad aspect, the composite structures of the 
present invention are based upon combining the fabric reinforcement with 
thermosetting or thermoplastic resins to form a sheet of composite 
material which is then shaped to produce the desired structure. 
These structures have surprising strength to weight ratios making them 
useful for a number of support applications. Moreover, because of the 
unexpected flexing characteristics imparted by the reinforcement material, 
the composite structures of the present invention are particularly well 
suited for situations where the support is subject to sudden impact. For 
instance the present invention would be particularly useful for the arch 
support of a shoe or to make an automobile dash safer in the event of an 
accident. While the material has inherent flexibility, those skilled in 
the art will appreciate that the flexibility may be altered by varying the 
matrix material, the amount of reinforcement used, or the orientation of 
the reinforcement material. 
Whereas prior art efforts have been focused on improving the flexibility 
and strength of composite structures through the use of multiple laminae, 
the present invention advantageously combines these properties within a 
single ply structure. While it is possible that the reinforcement material 
of the present invention may be incorporated using a multi-ply 
configuration, this is not necessary to impart the beneficial flexing 
characteristics. Therefore, composite structures may be made lighter 
through the use of less material while retaining the desired flexibility 
and strength. 
Of equal importance, the present invention accomplishes these results using 
materials and fabrication techniques which are relatively low in cost and 
compatible with modern production technology. For instance, the 
reinforcement fabric of the present invention is a unique combination of 
two less expensive components currently found in advanced composite 
materials. In addition, the impregnation or wetting procedures are easily 
adaptable to large scale production, as is the molding process. By 
avoiding the use of several lamina at different orientations the present 
invention avoids the labor intensive processes used to produce current 
composite structures with equivalent properties. 
The present invention involves the use of a unique reinforcement material 
which combines glass rovings with graphite tows in an architectural 
combination that retains the distinctive properties of each. 
Specifications for a preferred embodiment of the fabric are shown in Table 
1. 
TABLE 1 
______________________________________ 
FIBER TYPE 
WARP 12K GP CARBON FIBERS 
FILL 330 YIELD E-GLASS 
ROVING 
YARN COUNT 
WARP (PER INCH) 13 
FILL (PER INCH) 11 
FABRIC AREAL WEIGHT 
G/SQ M 32.1 (NOMINAL) 
THICKNESS 
DRY (AMES GAUGE) 0.034" 
@ 60% FIBER VOL. 0.032" 
______________________________________ 
Typically, the fabric can be manufactured using the glass rovings and 
graphite tows in several different weaves. The fabrics incorporated may be 
produced using standard equipment and techniques well known in the art. 
Using different weaves results in fabrics having varied anisotropic 
characteristics. Therefore through the use of different weaves the 
physical properties of the resulting reinforcement material may be 
configured for specific purposes. In particular the anisotropic 
flexibility of the resulting composite material may be altered relative to 
the longitudinal axis. 
Referring now to the drawings, the woven reinforcement material 10 made 
using a 2/2 twill weave pattern is shown in FIG. 1 with carbon tows 12 and 
glass rovings 14. The longitudinal axis 16 is shown running parallel with 
the graphite tows and the transverse axis 18 is shown running parallel to 
the glass rovings. FIG. 2 shows a perspective of the same material. The 
twill weave is characterized by diagonal lines, known as twill lines, that 
run at angles to the longitudinal axis and transverse axis. 
Other embodiments of the reinforcement material may be fabricated using the 
same components in two other common weaves. Plain weave 60 using the glass 
rovings 14 and graphite tows 12 are shown in FIG. 7 and a satin weave 70 
is shown in FIG. 8 again with the glass rovings 14 and graphite tows 12. A 
unique characteristic of the satin weave is there are no adjacent 
interlacements in a repeat. This produces a reinforcement material whose 
anisotropic properties are less defined than fabrics made from the other 
two weave and its flexibility is more uniform. 
In a preferred embodiment the 2/2 twill fabric weave 10 has a final yarn 
count of 13 warp fibers 12 per inch and 11 weft fibers 14 per inch. Other 
fabrics which may be used in this invention may have yarn counts from 5 to 
30 elements in both the weft and warp. The yarn count is a principal 
factor in determining the stiffness of the resulting composite materials. 
This specific weave and fiber content gave the embodiment a nominal weight 
of only 31.9 oz/yd.sup.2 A single-ply of the resulting fabric had a dry 
thickness of 0.034 inches using an Ames gauge and only 0.032 inches at 60% 
fiber volume. 
The anisotropic properties of the preferred embodiments may be imparted 
using graphite tows comprising either standard modulus carbon fibers or 
intermediate modulus carbon fibers. These fibers are commercially 
available and are sold under the names Hercules AS4C and Hercules IM-7 
(Hercules Corp., Wilmington, Delaware ) respectfully. Likewise the 
preferred 330 E-glass rovings are easily and inexpensively obtained. Among 
other sources, they are sold under the name Fiberglas (Owens Corning, 
Toledo, Ohio). 
One exemplary embodiment of the present invention combines this fabric with 
an epoxy based polymer resin system as a matrix. This particular resin is 
formulated to provide a very good shelf life in addition to good out time. 
Even with these attributes it still has a relatively rapid cure time of 
two minutes at 350.degree. F. These qualities promote high speed 
production capability. The catalytic system used provides a two stage cure 
with a large cure temperature window while still producing a good part. 
The mixing of the resin formulation is initiated with the addition of 
diglycidyl ether of bisphenol F into a reactor having mechanical mixing 
blades. Polyoxyalkyleneamine was then slowly added to the reactor and 
mixed at a constant temperature. Bisphenol A-novolac epoxy, with an 
average functionality of 3, is heated in an oven at 70.degree. C. for a 
few hours until it can be easily poured. The liquid is then charged into 
the reactor with good mixing. Carboxy terminated butadiene-acrylonitrile 
copolymers and carboxylated nitrile rubber solution (15% in MEK) are then 
added to the mixing reactor. The mixture is heated for at least 45 minutes 
at approximately 80.degree. C. The batch is then cooled to about 
40.degree. C. Polyglycidyl ether of bisphenol A (80% in acetone), titanium 
dioxide (TiO.sub.2) and antifoam (Antifoam 1400 from Dow Corning) are then 
added and mixed in well. The total mixture is stored in a cool area for 
further compounding. 
Just prior to adding the matrix to the reinforcement material, acetone is 
charged into the above mixture to make it a 65-70% total solid mixture. 
The catalysts dicyandiamide and 2-ethyl-4-methylimidazole are then added 
and the resulting formulation is given a good mixing for 15 to 20 minutes. 
During this period the mixing temperature was kept below 50.degree. C. In 
addition to having a good out time, this solution is found to be very 
stable over extended periods. 
While this particular dicatalytic resin system is suitable for practicing 
the present invention, those skilled in the art will recognize that 
numerous thermosetting resin systems with and without fillers may also be 
used in the invention. Compatible thermosetting resin systems useful in 
the present invention may be based on epoxies, polyesters, polyurethanes, 
or acrylics. Depending on the specific physical properties sought, 
different formulations of epoxy resins will provide suitable matrix 
materials. For instance, different crosslinkers may be substituted to 
improve the temperature compatibility of the matrix or modify the cure 
window. Other possible thermosetting resin matrix systems include 
polyimide, bismalemide and cyanate resins. Alternatively, the use of 
thermoplastic resins such as polycarbonates, polyetherimides, acrylics or 
thermoplastic polyurethane as matrix materials are contemplated as being 
within the scope of the present invention. 
In addition to several matrix systems described above it will be 
appreciated by those skilled in the art that there are several different 
processes which can be used to produce the combination of reinforcement 
material and uncured resin known as prepreg. In preferred embodiments this 
uncured composite material or prepreg may be stored for some time before 
being cured and shaped to form the desired composite structure. The 
wetting process used to produce the prepreg may involve drawing the 
reinforcement through the liquid resin while other processes spray the 
liquid matrix or employ a hot melt procedure. In a hot melt process the 
solid resins are first cast into films on release paper and later 
deposited on or impregnated in fabrics using slight heat and pressure. 
Thus, by controlling the application process, the deposition of the matrix 
may occur only on the surface of the reinforcement or it may be 
impregnated throughout. This can substantially alter the properties of the 
composite structures as desired. 
Referring now to FIG. 3, in a preferred embodiment the reinforcement 
material is first installed onto the fabric let-off roll 20. The liquid 
resin system 26 is placed into the dip pan 24 under the vertical drying 
ovens or towers 30. A series of rollers 10,22,36 keep the tension on the 
reinforcement material uniform and help keep the speed constant. Under 
this proper tension the fabric cloth is slowly pulled through the dip pan, 
and up through the drying towers. The temperature in both towers is in the 
range of 93.degree. C. to 104.degree. C. with the run speed of 6-10 feet 
per minute for this particular embodiment. Following the passage through 
the heating towers, the fabric wetted with the resin is passed over a 
chilled roller 32 and through an accumulator rack 34. The final product is 
then collected on a take-up roll 40 as shown in FIG. 3. 
These processing conditions are capable of producing a prepreg with resin 
content in the range of 26 to 33% by weight and a volatile solvent 
concentration of 0.5% to 1.5% by weight. It will be appreciated by those 
skilled in the art that these matrix concentrations may be varied by the 
formulation of the matrix or method of application. The solid content of 
the resin system in the dip pan is monitored by periodically checking the 
specific gravity which is 1.050+/-0.010. The finished product is 
immediately stored in a -10.degree. F. to 0.degree. F. freezer. The shelf 
life for this prepreg at storage is approximately three plus months. The 
out-time at room temperature is about 24 hours. 
Other preferred embodiments of the invention involve the use of 
thermoplastic materials to provide the matrix. Thermoplastic materials 
including, but not limited to, polycarbonates, polyetherimides, acrylics 
and polyurethanes are provided in sheet form with a thickness of 10 to 30 
mm. These sheets are cut to the proper size and used directly in the 
commercially available form. In this embodiment of the invention the 
thermoplastic sheets are then used to sandwich the fabric reinforcement 
and, without further preparation, the thermoplastic sandwich is placed in 
the mold. However it is to be appreciated that the thermoplastic 
reinforcement combination may be stored in the sandwich configuration for 
an indefinite period. Further the combination of reinforcement fabric and 
thermoplastic sheets may be rolled at an elevated temperature to form 
sheets of thermoplastic composite material. These sheets may then be 
stored until ready for use in manufacturing. 
The preferred process for producing a finished part from the polymer resin 
impregnated fabric utilizes a molding techniques. Referring to FIG. 4 the 
male mold side 46 has a face 44 of hard tooling such as aluminum or steel 
and the female side 48 is soft tooling such as silicon or polyurethane 
pressure bag. Thermoplastic sandwiches, sheets of thermoplastic composite 
material or prepreg are cut to the dimension of the mold and to a length 
equivalent to the length of an arbitrary number of ganged molds. The 
selected material 10 is then placed between the two mold faces with the 
reinforcement fabric oriented so its anisotropic properties will be 
expressed as desired in the finished composite structure. The selected 
material is then pressed at an appropriate temperature and pressure for an 
effective amount of time. Shaped composite materials having anisotropic 
properties are then removed from the mold. 
As is seen in FIG. 5 the desired part 50 is cut from the composite material 
using conventional methods including water jet cutting 52. The 
longitudinal axis 16 and transverse axis 18 of the reinforcement material 
are clearly exhibited in the composite material. 
FIG. 6 shows the finished composite structure 50 being used as an arch 
support in a shoe 54 to absorb and distribute the forces generated by 
walking. In distributing forces on the foot such a support will provide 
the desired stiffness along the longitudinal axis while allowing increased 
flexibility along the transverse axis. 
EXAMPLE 1 
A thermosetting resin composite arch support for use in a shoe was 
fabricated as follows. 
Several square yards of novel fabric reinforcement was manufactured using 
glass rovings and graphite tows. The graphite fiber used for the warp yarn 
was 12K GP 0.8% min. (Thornel T300 or Hercules AS4C provided by Amoco 
Corp. and Hercules Corp respectively). This warp yarn was then interlaced 
with filling yarn consisting of 330 roving E-glass (Fiberglas, Owens 
Corning). The resulting fabric had a final yarn count of 13 warp fibers 
per inch and 11 fill fibers per inch. For this embodiment the glass and 
graphite fabric was woven using a 2/2 twill weave pattern. This specific 
weave and fiber content gave the fabric a nominal weight of 31.9 
oz/yd.sup.2 A single-ply of the resulting fabric had a dry thickness of 
0.034 inches using an Ames gauge and 0.032 inches at 60% fiber volume. 
This exemplary resin formulation is begun by placing an amount of 
diglycidyl ether of bisphenol F (LY 9703, Cibia-Geigy) equal to 5.17 parts 
by weight into a reactor with mechanical mixing blades. 
Polyoxyalkyleneamine (Jeffamine T5000, Texaco Corp.) equivalent to 2.58 
parts per weight was then slowly added and mixed with the LY 9703. The 
mixing temperature was kept below 80.degree. C. Bisphenol A-Novolac Epoxy 
(SU-3, Rhone-Poulenc) was preheated in an oven at 70.degree. C. for a few 
hours until it could be easily poured. Following the heating the SU-3 was 
then added in an amount equivalent to 23.26 parts into the reactor with 
good mixing. Two types of carboxyl terminated butadiene-acrylonitrile were 
then added at 2.71 parts each (CTBN 1300.times.13 and 1300.times.18 both 
from B.F Goodrich). This was followed by 2.33 parts of carboxylated 
nitrile rubber (Hycar 1472 solution [15% in MEK] from B.F. Goodrich) which 
was added to the reactor with continuous mixing. The mixture was heated 
for 60 minutes at 80.degree. C. The batch was then cooled to 40.degree. C. 
and Polyglycidyl ether of bisphenol A (Der 661 80A, 80% Der 661 in 
acetone) was then added to the mixture in an amount equivalent to 54.26 
parts. Finally 1.0 pph TiO.sub.2 (Ti-pure R-900 from Dupont Inc.) and 
0.003 pph Antifoam 1400 (Dow Corning) were added. The total mixture was 
stored at a cool area for further compounding. 
Just prior to the making of prepreg, acetone was charged into the above 
mixture to make it a 65-70% total solids mixture. The catalysts 
Dicyandiamide and EMI 24 were added with good mixing for 15 to 20 minutes 
and the mixing temperature was kept below 50.degree. C. 
The fabric cloth described in this example was then installed onto the 
fabric let-off roll 20 of the apparatus shown in FIG. 3. The resin system 
26 was charged into the dip pan 24 under the vertical drying ovens 30 
(towers). Under proper tension maintained by a series of rollers the 
fabric cloth was slowly pulled through the dip pan, and up through the 
drying towers 30. The wetted reinforcement was then passed over a chilled 
roller 32 and through an accumulator rack 34 before it reached the final 
product take-up roll 40 as seen in FIG. 3. 
The temperature in both towers was 100.degree. C. with the run speed of 7 
feet per minute. These processing conditions produced prepreg with resin 
content in the range of 26 to 33% by weight and a volatiles content of 
0.5% to 1.5%. The solids content of the resin system in the dip pan was 
monitored by periodically checking the specific gravity which is 
1.050+/-0.010. The finished product was immediately stored in a 
-10.degree. F. freezer. The shelf life was approximately three plus 
months. The out-time at room temperature was about 24 hours. 
Impregnated with resin, the fabric was now cut into strips with dimensions 
of 41/4" by 22". These pieces of impregnated fabric were large enough to 
cover the face of the molds. The press mold itself had a male side 
constructed of steel and a female side of soft, silicone tooling. The mold 
faces were brought together and pressure was applied at 50 pounds per 
square inch. Mold temperature was maintained at 350.degree. F. as the part 
was cured for two minutes. Alternatively, the mold temperature could be 
maintained at 300.degree. F. while the part was cured for three minutes. 
Both sets of parameters gave products with satisfactory properties. 
Following this, the mold was separated and the cured fabric strip removed. 
The finished part was then cut from the fabric blank using a conventional 
water jet cutting apparatus. 
Table 2 lists some of the properties inherent in the composite material 
fabricated according to the example above. 
TABLE 2 
______________________________________ 
Tensile Strength (ksi) 
57 
Tensile Modulus (msi) 6.1 
Tensile Strain (%) 2.14 
Flexural Strength (ksi) 
56 
Flexural Modulus (msi) 
5.5 
Flexural Fatigue Modulus (msi) 
5.0 
(After 1 Million Cycles) 
Flexural Fatigue Strength (ksi) 
44 
(After 1 Million Cycles) 
______________________________________ 
1. The panel was a single ply of material tested in the direction of the 
graphite fibers. 
2. Resin Content 28-30% by weight. 
EXAMPLE 2 
The graphite glass reinforcement was made as described above and cut to 
predetermined sizes. A piece of the reinforcement fabric described in 
example 1 was sandwiched between two polycarbonate thermoplastic sheets 
(Lexan from General Electric Plastics) 15 mm in thickness. The sandwich 
was then placed inside steel molds which were then heated to 550.degree. 
F. The mold was also kept under pressure at 100 psi. These conditions were 
maintained for a period of three minutes. The parts were cooled to ambient 
temperature and then were removed from the mold. The part was then trimmed 
to the final shape by conventional methods, such as water jet cutting. 
Having thus described exemplary embodiments of the present invention, it 
should be noted by those skilled in the art that the disclosures herein 
are exemplary only and that alternative, adaptations, and modifications 
may be made within the scope of the present invention. Accordingly, the 
present invention is not limited to the specific embodiments illustrated 
herein.