Composite prepreg constructions as disclosed herein are manufactured in a manner that provides an improved degree of air removal during consolidation and cure while retaining all resin in the prepreg plies to thereby produce a composite structure having greatly reduced or eliminated internal porosity and aesthetically unacceptable surface defects.
Currently, composite parts as made for use in such applications as aerostructures and the like are produced from prepregs (i.e., a partially cured, fiber-reinforced precursor material already impregnated with a synthetic resin) that are consolidated/cured in autoclaves. These processes limit production rates and part sizes, and attach significant cost burdens, both capital and operating, to the production of such parts. The use of an autoclave for making composite parts or structures from prepregs thus presents a production bottleneck. For example, to reach future production rates required for the manufacture of single-aisle aircraft, alternatives to autoclave cure of prepregs that are faster and less costly must be identified, or such aircraft will not be designed with composite materials.
Out of autoclave (OoA) prepregs (prepregs cured outside of an autoclave) and methods for making the same are known, and have been developed to address these problems and provide a route around the bottleneck. Such known OoA prepregs feature channels for evacuating or air or gas during processing and cure that are located in the plane of the fiber bed. Basically, fiber beds (woven fabric or unidirectional (UD) fibers) are partly impregnated with resin film, leaving dry fiber channels at the mid-plane to facilitate air removal during cure. These “breathing pathways” are effective for in-plane air removal, i.e., through the ends of the prepreg, but offer little or no ability to evacuate air or gas in the out-of-plane or through-thickness direction due to the presence of the resin covering the top and/or bottom surfaces of the fiber bed. As a result, limitations arise when making (a) large parts with long breathe-out distances, and (b) parts with corners, ply drop-offs, or other geometric features which occlude the in-plane “breathing pathways” and trap air in the part. Further, the use of such conventional OoA prepregs also requires meticulous attention to detail during part production. Additionally, it is often desired to repair a damaged composite prepreg part or structure. Such known OoA prepreg formats that rely on in-plane air or gas removal do not allow for a high quality repair because the repair geometries typically occlude the in-plane air or gas breath out paths of the prepreg during processing and cure.
One approach to address the lack of through-thickness “breathing pathways” in such traditional prepreg formats is embodied in “Z-preg”, a prepreg format featuring wide resin strips applied to dry woven fabric, which affords additional through-thickness air or gas permeability. A drawback to Z-pregs and conventional OoA prepreg formats, and the prepreg products, structures, and parts formed therefrom, is resin-flow issues during processing, including excessive resin bleed, lack of complete resin saturation of the fabric leading to resin-starved regions, and premature occlusion of breathing pathways. Because of both the large spacing between resin strips and the large width of the resin strips in Z-preg, the drawbacks cited above are problematic, and thus Z-preg is not widely used to form composite products, structures or part.
Another approach to address the lack of through-thickness “breathing pathways” in such traditional prepreg formats, and to improve on the through-thickness “breathing pathways” provided by the Z-preg is embodied in a prepreg comprising resin provided in the form of a plurality of discrete resin regions on the surface of the fiber bed rather than being provided in the form of the wide resin strips as with the Z-preg. While the prepreg construction comprising the plurality of discrete resin regions provides improved features of resin flow such as a better degree of impregnation and saturation of the fiber bed and a reduced degree of through-thickness breathing pathway occlusion during processing when compared to the Z-preg, there still exists resin issues that occur during process that impacts the ability to produce products, structures, or parts having a desired reduced degree of internal porosity and minimal surface defects.
There is, therefore, a need/desire to develop a more robust prepreg format and approach for prepreg processing that functions to both overcome both the bottleneck issue associated with using autoclaves, and addresses the above-noted limitations associated with the known OoA approach of processing prepregs into composite structures.
Prepreg assemblies and composites as disclosed herein comprise a through-thickness air or gas permeable prepreg comprising a fiber bed and a plurality of discrete resin regions disposed on a surface of the fiber bed. In an example, the fiber bed is unidirectional. In an example, the discrete resin regions are configured having a uniform pattern on the fiber bed surface. In an example, the discrete resin regions are formed separately from the fiber bed and are disposed thereon in a preformed state. In an example, the discrete resin regions are formed by depositing a film of resin on a carrier and de-wetting the film of resin to form the discrete resin regions, and wherein the discrete resin regions are disposed on the fiber bed surface by pressing a surface of the carrier comprising the discrete resin regions into contact with the fiber bed surface and removing the carrier therefrom.
In an example, the discrete resin regions are separated by exposed surface regions of the fiber bed that are not covered by the discrete resin regions, wherein the exposed surface regions facilitate the through-thickness permeation of air or gas therethrough during processing. Prepregs as disclosed herein may comprise two or more piles in laminate form comprising fiber beds and discrete resin regions disposed on one or both sides of each of the fiber beds
Prepreg assemblies used for processing such through-thickness permeable prepregs disclosed above comprise such prepreg as combined with an air permeable resin barrier material that disposed over the surface of the prepreg that is opposite a forming tool. The air permeable resin barrier material is permeable to air or gas passing from the prepreg and is impermeable to resin passing from the prepreg. In an example, the prepreg discrete resin regions and exposed fiber bed surface region are configured to facilitate air or gas removal from the prepreg in a through-thickness direction of the prepreg during a prepreg curing process. The air permeable resin barrier material is configured to permit such air or gas removal from the prepreg while also preventing resin passage from the prepreg during such prepreg curing process. In an example, the prepreg assembly may further comprise a bag disposed over at least a portion of the prepreg assembly for subjecting the prepreg assembly to a vacuum condition.
Methods for processing such through-thickness permeable prepregs disclosed above comprise combining such prepregs with the air permeable resin barrier material to form an assembly as disclosed, and subjecting the prepreg assembly to vacuum and elevated temperature conditions that cures the resin to form a composite structure, product, or part therefrom. In an example, the prepreg may be formed by depositing the discrete resin regions onto the surface of the fiber bed. In an example, the discrete resin regions are formed by depositing a resin film onto a surface of a carrier that is separate from the fiber bed and treating the resin film to cause the resin film to disperse into the discrete resin regions. In an example, the discrete resin regions on the surface of the carrier are deposited onto the surface of the fiber bed by pressing the surface of the carrier comprising the discrete resin regions into contact with the fiber bed surface so that the discrete resin regions adhere to surface of the fiber bed and are transferred from the surface of the carrier. In an example, the method may further comprise placing a bag over the prepreg and the air permeable resin barrier material for subjecting the prepreg to a vacuum condition during the curing process.
During the process of subjecting, air or gas permeates in a through-thickness direction from the prepreg and passes from the surface of the prepreg through the air permeable resin barrier material thereby promoting efficient air or gas removal from the prepreg to prevent trapped air or gas from forming voids or pores in the composite structure, product, or part. During the process of subjecting, resin passage from the surface of the prepreg is restricted or prevented by the air permeable resin barrier material thereby reducing or mitigating resin pressure loss during processing and the associated unwanted formation of bubbles and resulting internal void or pore formation. In an example, during the step of subjecting, the prepreg discrete regions of resin flow and saturate the fiber bed and the resin maintains at least about 50 percent, and from about 60 to 100 percent of its pressure through the step of curing. In an example, the resulting composite structure, product, formed in accordance with such method comprises less than about two percent by volume internal porosity.
Through-thickness permeable prepregs and assemblies comprising the same as combined with the air permeable resin barrier material as disclosed above (in place of a conventionally used perforated release film discovered to be resin permeable) for prepreg processing under vacuum and elevated temperature conditions are specifically constructed to maintain resin pressure during such processing conditions as a result of restricting or preventing unwanted resin bleed that effectively reduces or eliminates the formation of unwanted internal voids caused by trapped resin volatiles or bubbles to thereby produce composite structures, products, or parts having reduced internal voids and pores.
Other apparatus, systems, methods, features, and advantages of prepregs and approaches and methods for processing the same as disclosed herein will be appreciated as the same becomes better understood by reference to the following detailed description and attached materials when considered in connection with the accompanying drawings wherein:
Disclosed herein are apparatuses, systems, and methods to produce composite prepreg constructions with high permeability in the through-thickness direction and having near-zero internal porosity. A feature of the process of making prepregs as used herein is the process used to provide discrete resin regions on a fiber bed and leaving regions of the fiber bed surface not covered with discrete resin regions exposed (gaps), e.g., unidirectional fiber, or woven fabric or non-crimp fabric or a textile, thus greatly facilitating through-thickness air removal from the prepreg during consolidation and cure during processing, e.g., under vacuum and elevated temperature conditions, to form composite products, structures, or parts and thereby reducing/eliminating strength-limiting porosity. A further feature as disclosed herein is the method and assembly used for processing the prepregs as disclosed herein that makes use of an air permeable resin barrier material (in place of a conventional perforated release film) as combined with the prepreg to reduce/eliminate resin bleed or resin migration from the prepreg during processing to retain resin pressure throughout processing and thereby avoid an unwanted creation of voids or porosity within the cured composite product due to resin pressure loss. As used herein, and as understood in the art, the term “fabric” is interchangeable with “woven fabric” or “non-woven fabric.” The gaps or discrete resin regions may have various geometric configurations, including parallel strips or grids or may be randomly configured. Other configurations such as various patterns (regular and irregular), among others, may be provided. The gaps may surround discrete islands of resin. The gaps may comprise perforations in a film.
The distribution of polymer resin according to methods and principals disclosed herein for making prepregs useful for making prepreg assemblies for forming composite products, structures, or parts as disclosed herein contrasts with such conventional methods of making prepregs intended for Out-of-Autoclave curing (OoA). Such prepregs useful for making prepreg assemblies for forming composite products, structure, or parts as disclosed herein generally comprise a number of discrete resin regions disposed on a surface of a fiber bed. The discrete resin regions comprise discontinuous resin on the surface of the fiber bed. The discrete resin regions serve to enhance the through-thickness air or gas permeability of the prepregs to thereby enhance removal of air or gas from the prepreg during a debulking and curing processes. Various patterns (regular or irregular) of the discontinuous resin may be applied to the surface of the fiber bed. In methods disclosed herein, the discrete resin regions may comprise resin islands, or a number of discrete pore regions within the resin (or a resin grid). In certain embodiments, perforated resin films may be applied to the surface of the fiber bed.
In methods disclosed herein, a distance between the resin regions may be measured to provide desired exposed portions of the fiber bed surface to facilitate permeation of air or gas through the exposed portions of the fiber bed surface in a direction perpendicular to a plane of the fiber bed during a curing process of the prepreg. The measuring may include controlling, prescribing, designing, creating, or performing other forms of measuring. The distance may be determined to produce a desired result, as discussed regarding methods herein.
The methods disclosed herein may also contrast with conventional methods of making prepregs because the methods disclosed herein may not rely on the particular surface topography or architecture of the fiber bed to form the discrete resin regions. Prior forms of deposition may form resin regions by relying on raised or heightened portions of a fabric weave to cause the resin regions to be formed (e.g., relying on a raised contact surface of the fiber bed, which may contact a roller or the like). The methods disclosed herein may be utilized with multiple forms of fiber beds (fabric or unidirectional fiber bed or a non-crimp fabric or a textile) having multiple forms of surface topography or architecture. The methods disclosed herein may be utilized with a fiber bed having no significant surface perturbations, such that the surface of the fiber bed may be considered to be flat. This is a feature recognized with unidirectional fiber beds. The methods disclosed herein accordingly differ from prior methods, which may rely on the surface topography or architecture of the fiber bed to produce discrete resin regions, and may not be usable with unidirectional fiber beds.
One method for forming such prepregs is by a process of applying a configuration of a number of discrete resin regions to a surface of a fiber bed by applying a printing surface to the surface of the fiber bed. The printing surface may have recesses corresponding to the configuration and that include the resin. Application of the printing surface comprising the recesses containing the resin to the surface of the fiber bed effectively applies the discrete resin regions to the fiber bed surface.
The surface 503 of the fiber bed 502 may be passed along the printing surface 505 to apply the discrete resin regions 510 thereon. As shown in
The recesses 508 of the printing surface 505 may comprise grooves as shown in
The processes of
The processes of
In one embodiment, the methods of
The droplet deposition process may involve spraying droplets of the resin material upon the surface 704 of the fiber bed 706. A desired configuration of discrete resin regions 702 may result on the surface 704. In
The droplet deposition may occur through a droplet deposition apparatus 710, which may include one or more nozzles 712 coupled to a frame 710. The nozzles 712 may be configured to move relative to the fiber bed 706 to apply a desired configuration of discrete resin regions 702 to the surface 704. The nozzles 712 or fiber bed 706 may be configured to move relative to each other to allow for movement in the x-axis direction or the y-axis direction (or the z-axis direction). The nozzles 712 may deposit the droplets in this manner upon the surface 704.
The processes of
The processes of
In step (a) of
Step (b) of
The arrow between the two images of step (b) of
In step (c) of
In one embodiment, the resin film 914 (previously imprinted or not) may be positioned on the fiber bed 906 prior to the de-wetting process. In such embodiment, the resin film 914 may be imprinted on the fiber bed 906 and may be de-wetted after the resin film 914 is applied or transferred to the surface of the fiber bed 906. In one embodiment, the resin film 914 may be imprinted prior to being applied to the fiber bed 906 and may be de-wetted after being applied to the fiber bed 906. In embodiments, resin material may be de-wetted prior to, during, or after the resin material is deposited onto the surface of the fiber bed.
The processes of
In one embodiment, the processes of
While one approach of forming the discrete resin regions by de-wetting has been disclosed above and illustrated in
The methods of de-wetting as disclosed above make use of backing substrates or carriers that have no surface features useful for causing formation of the discrete resin regions. However, it is to be understood that backing substrates comprising certain surface features such as ridges or the like may be used to provide nucleated de-wetting that functions to physically cause formation of the discrete resin regions during the de-wetting process.
A distance 1026 between the resin regions 1016 may be set such that limited resin flow is required to close the gap between resin regions 1016 during curing. In embodiments according to the methods disclosed herein, the distance 1026 may have a range of between 0.1 millimeters (mm) and 10 mm. In other embodiments, other ranges of distances 1026 may be utilized. In embodiments, the distances may be determined based on resin chemistry, desired temperature cure cycles, and/or end-use application, among other factors.
The prepreg 1010 disclosed in
The processes disclosed herein may not only be used to produce prepregs with unidirectional fiber beds, as disclosed in
The use and presence of discrete resin regions 1016 with a unidirectional fiber bed, and the processes of making such a prepregs with a unidirectional fiber bed, as disclosed herein, are novel, as well as the other methods, apparatuses, and systems disclosed herein.
A benefit of the air channels formed in the through-thickness direction of the prepregs disclosed herein is reduced void formation (both internal voids or internal porosity and surface voids). The through-thickness air channels allow for improved withdrawal of air or other gas during prepreg processing such as during a curing process, which may include vacuum processes and a heating process. A much greater through-thickness permeability is produced to enhance air removal to thereby promote processing efficiency, and reduce defects in parts. Prepregs produced as disclosed herein may result in composite structures, products, or parts formed during a curing process having near-zero internal void formation (near-zero porosity) and flawless external surfaces.
The composite part formation and curing processes disclosed herein may include a process of layering multiple prepregs (prepreg plies), such as the prepreg 1010 shown in
Prepregs made according to the methods disclosed herein may comprise materials conventionally used to form prepregs, which may include and not be limited to carbon or glass fiber, and epoxy, polyimide, BMI, cyanate ester, polyurethane, phenolic, or other polymer resin and the like.
A benefit common to all of the prepreg embodiments disclosed herein is that the selection of widths and spacing of the discrete resin regions affords control of the resin distribution both in the prepreg and in the resulting composite product, structure, or part formed therefrom. An advantage of such prepregs as disclosed herein over most commercial prepregs is the greater through-thickness air or gas permeability, which enables and facilitates air and gas removal from the prepreg during processing and cure when in-plane channels are inadequate. A further feature and advantage of the methods disclosed herein may be that the resin is applied to fiber beds by a continuous process that affords control of the spatial distribution of the resin. The methods disclosed herein may remove the present part size limitation inherent with current OoA processing methods, and make the process of producing composite parts with OoA prepregs more robust by promoting through-thickness (in addition to in-plane) air removal. The methods disclosed herein also may occur independent of a surface topography or architecture of the underlying fiber bed, which enhances the breadth of utility of the processes and may reduce processing expenses.
Additionally, prepregs as disclosed herein allow for flexibility in processing in that such prepregs may be made and then subsequently subjected to processing for forming desired composite products, structures, or part in a continuous process. Alternatively, prepregs as disclosed herein may be made and then stored for processing at a later date. In an example, prepregs as disclosed herein may be rolled, stacked, folded, or the like and stored for a period of time until later subjected to processing. This ability to store the prepregs enable the prepregs to be made at one location and then processed at another location adding geographic flexibility to the process of making and the subsequently processing the prepregs. A further feature of the prepregs disclosed herein is that they contain all of the resin (in the form of the discrete resin regions) for processing and forming a resulting composite structure, product, or part such that no further resin is added to the prepreg (i.e., by injection or other process) before or during processing.
Thus, the methods as disclosed herein for making prepregs may enable production of high-quality composite products, structures, or parts, including large parts and parts having complex geometries, and do so in a manner avoiding the need to use autoclaves. The prepreg constructions and products resulting from such methods as disclosed herein may have formats (resin and fiber distributions) that are optimized for production of challenging parts.
Prepregs as disclosed herein are processed to form a desired composite structure, product, or part by combining the prepreg with a suitable forming tool and, in an OoA process, sealing the prepreg within a bag that is configured to receive vacuum and in an example placing the assembly in an oven for subjecting the assembly to a desired elevated processing temperature. Alternatively, such process may also be achieved using a heated forming tool or by placing a heating member such as a heating blanket or the like over the assembly, wherein such heating blanket may comprise heating elements such as resistive heating elements and such heating elements may be controlled by a control system to provide desired temperature cycles. Accordingly, it is to be understood that methods for processing prepregs as disclosed herein is not limited to oven-based curing approaches. In an example embodiment, the processing vacuum pressure may be from about 0 to 1 PSI, the elevated temperature may be from about 100 to 200° C., and the processing time may be from about 20 to 500 minutes. It is to be understood that such prepreg processing conditions can and will vary from that provided above depending on such factors as the type of resin being used, and thickness or number of plies used to make up the prepreg, the total size of the prepreg, and the like.
During processing, the prepreg processing assembly 1100 is subjected to the vacuum and temperature conditions as noted above. During an initial step or debulking stage of processing the assembly is subjected to the vacuum condition without heating for purposes of removing air from the prepreg through the exposed surface of the prepreg fiber bed. Ideally, it is desired to remove substantially all of the air from the prepreg during this initial step. In a second step, while the vacuum condition is maintained, the assembly is heated or subjected to an elevated temperature causing the discrete resin regions in the prepreg to flow together and fill or impregnate the manufactured dry regions in and throughout the prepreg fiber bed. The vacuum and temperature condition is maintained for a period of time to ensure that the fiber bed is completely saturated and to cure the resin when the fiber bed is in such completely saturated state.
Using such conventional processing assembly 1100 and method described above and illustrated in
For purposes of better understanding the cause of such unwanted internal and surface porosity or voids, the pressure behavior inside of the prepreg during processing was monitored. In an example, a pressure measurement device comprising a pressure sensor or transducer (e.g., a Honeywell Model S transducer) attached with an element comprising a reservoir filled with a high-temperature oil transfer medium (e.g., synthetic oil rated for use up to 200° C.) was developed. A needle tube or probe (19-gauge stainless steel with a 90 degree tip) extended from the element and was sized having a sufficient length to extend from a position outside of the prepreg processing assembly (removed from processing vacuum and temperature condition) into the prepreg processing assembly. The needle tube or probe had an open end that was disposed into the prepreg between piles (exposed to the processing vacuum and temperature condition and in contact with the resin within the prepreg during processing), wherein the needle tube was sealed with a small amount of excess resin to prevent a pressure loss during the initial vacuum application but once it was exposed to elevated temperatures the excess resin became liquid (prior to curing) and enabled direct measurement of liquid resin pressure. In an example, the probe was oriented parallel to the tool plate and the prepreg or laminate, was inserted between second and third piles of the prepreg or laminate.
Using such pressure measurement device it was discovered that during the second step of processing a pressure drop in the resin occurred that was determined to be associated with the migration or flow of resin within the prepreg to fill the manufactured dry spots of the fiber bed. After this initial pressure drop in the resin, during further processing it was discovered that the resin pressure within the prepreg continued to drop, so that the pressure being imposed on the prepreg by the vacuum conditions and the associated pressure force inside the prepreg was shifting from the resin to the fiber bed, i.e., the resin was no longer carrying the pressure load. The resin pressure characteristics described above are illustrated in
To address this issue, a solution for minimizing and/or eliminating such unwanted resin bleed from the prepreg surface during processing was investigated. As the perforated release film was discovered to be the cause for the resin bleed, it was eliminated. In its place an air permeable resin barrier material was tested, as such material was specially engineered to preserve air permeability while preventing resin passage. In an example, the air permeable resin barrier material may be referred to as a semipermeable membrane that permits air flow and prohibits or prevents resin flow. In an example, an air permeable resin barrier suitable for use during prepreg processing may be used is one made by Airtech International Inc., such as Dahltexx SP-2 made from nylon and that is in the form of a membrane having a micro-porous structure specially configured to allow air or gas passage and restrict the flow of resin, wherein information concerning this material is hereby incorporate herein by reference. While an example air permeable resin barrier material has been disclosed, it is to be understood that other materials or products may be used that provide the same or similar function (to permit air passage and restrict or prevent resin passage), and that all such other products are intended to be within the scope of this description.
The above-described prepreg processing assembly 1200 was subjected to processing under vacuum and temperature conditions as disclosed above for the conventional prepreg process assembly 1100 of
After processing, the prepreg processing assembly 1200 was disassembled and inspected for any indication or signs of resin bleed and there was no sign resin bleed that was observed from the surface of the prepreg 1200 indicating that the air permeable resin barrier material functioned to prevent unwanted migration of resin from the surface of the prepreg during processing. The composite structure, product, or part formed from the prepreg processing using the air permeable resin barrier material was both surface inspected and cross-sectioned for evidence of internal voids or pores, and very few if any internal or surface voids or pores were observed. In an example, the composite structure, product, or part formed in accordance with using the prepreg processing assembly 1200 of
In example conventional prepreg processing assemblies (such as that illustrated in
A feature of prepreg constructions and assemblies as disclosed herein comprises use of the composite prepreg of the type disclosed above having high air or gas permeability in the through-thickness direction as combined with an air permeable resin barrier material or semipermeable membrane in place of a perforated release film, and in an example with side edges of the prepreg laminate sealed. Such prepreg constructions facilitate air evacuation over the entire prepreg surface, while retaining all resin in the prepreg plies during processing (thereby preserving the original resin content and preserving the original fiber:resin ratio or proportions of the prepreg). The efficiency of air removal during processing reliably prevents voids due to entrapped air, while the prevention of resin bleed during processing from use of the air permeable resin barrier material ensures that resin pressure is maintained (and thus avoids void formation due to resin volatility). As noted above, prepreg constructions as disclosed herein make use of through-thickness permeable prepregs that comprise a resin:fiber ratio that is fixed before being combined with the air permeable resin barrier material and other elements to form the prepreg processing assembly for processing, e.g., under vacuum and elevated temperature conditions. Before, or during such processing of the prepreg there is no further resin that is provided, e.g., by injection or other technique, such that the only resin present is that initially provided in the form of the discrete resin regions disposed on the fiber bed.
Exemplary embodiments of the methods/systems/constructions have been disclosed in an illustrative style. Accordingly, the terminology employed throughout should be read in a non-limiting manner. Although minor modifications to the teachings herein will occur to those well versed in the art, it shall be understood that what is intended to be circumscribed within the scope of the patent warranted hereon are all such embodiments that reasonably fall within the scope of the advancement to the art hereby contributed, and that that scope shall not be restricted except in light of the appended claims and their equivalents.
The prepreg constructions and assemblies as disclosed herein may be utilized in a variety of industries, including production or repair of composite parts for aerospace (including aircraft parts, aircraft body parts, fuselage parts, among others) and sporting goods (including sailing masts, bicycle frames, and fishing rods), among other industries. Industries may also include composite parts for wind power, and automotive. Other applications may include medical (prosthetics, among others). The resulting composite parts disclosed herein may include aircraft parts, aircraft body parts, fuselage parts, wing parts, other aerospace parts, sailing masts, sail boat body parts, tennis racket handles, golf clubs, other sporting good parts, wind power generation parts, other wind power parts or power generation parts, automotive body parts (e.g., bumpers, frames, etc.), other automotive parts, prosthetics, other medical parts, among other composite parts and industries.
In closing, it is to be understood that although aspects of the present specification are highlighted by referring to specific embodiments, one skilled in the art will readily appreciate that these disclosed embodiments are only illustrative of the principles of the subject matter disclosed herein. Therefore, it should be understood that the disclosed subject matter is in no way limited to a particular methodology, protocol, and/or reagent, etc., described herein. As such, various modifications or changes to or alternative configurations of the disclosed subject matter can be made in accordance with the teachings herein without departing from the spirit of the present specification. Lastly, the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of systems, apparatuses, and methods as disclosed herein, which is defined solely by the claims. Accordingly, the systems, apparatuses, and methods are not limited to that precisely as shown and described.
Certain embodiments of systems, apparatuses, and methods are described herein, including the best mode known to the inventors for carrying out the same. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the systems, apparatuses, and methods to be practiced otherwise than specifically described herein. Accordingly, the systems, apparatuses, and methods include all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described embodiments in all possible variations thereof is encompassed by the systems, apparatuses, and methods unless otherwise indicated herein or otherwise clearly contradicted by context.
Groupings of alternative embodiments, elements, or steps of the systems, apparatuses, and methods are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other group members disclosed herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.
Unless otherwise indicated, all numbers expressing a characteristic, item, quantity, parameter, property, term, and so forth used in the present specification and claims are to be understood as being modified in all instances by the term “about.” As used herein, the term “about” means that the characteristic, item, quantity, parameter, property, or term so qualified encompasses an approximation that may vary, yet is capable of performing the desired operation or process discussed herein.
The terms “a,” “an,” “the” and similar referents used in the context of describing the systems, apparatuses, and methods (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein is intended merely to better illuminate the systems, apparatuses, and methods and does not pose a limitation on the scope of the systems, apparatuses, and methods otherwise claimed. No language in the present specification should be construed as indicating any non-claimed element essential to the practice of the systems, apparatuses, and methods.
This application claims the benefit and priority of U.S. Provisional Patent Application No. 63/283,967 filed Nov. 29, 2021, entitled “COMPOSITE PREPREG CONSTRUCTIONS AND METHODS FOR MAKING THE SAME,” the entire disclosure of which is hereby incorporated by reference in its entirety.
This invention was made with United States government support under Contract No. NSF PFI-TT-1827788 by the National Science Foundation. The United States government has certain rights in this invention.
Filing Document | Filing Date | Country | Kind |
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PCT/US2022/045277 | 9/29/2022 | WO |
Number | Date | Country | |
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63283967 | Nov 2021 | US |