Patent Application
20240391204
The use of hydrogen as a fuel source is becoming more common as an alternative to carbon-based materials. To increase the use of hydrogen, it becomes necessary to provide improved methods and devices for dispensing hydrogen, for instance in dispensing hydrogen for use as an automobile fuel. Data from the National Fuel Cell Technology Evaluation Center shows that the primary reason for hydrogen station shutdown is due to issues with the hydrogen dispensing system, of which the hydrogen dispensing hose plays a major role. Moreover, with relatively few hydrogen fueling stations available it is of paramount importance that such shutdowns are minimized and that consumers can be confident in the ability to obtain fuel as needed. Through development of improved hydrogen dispensing systems consumer confidence will be increased, leading to increased use of hydrogen as a fuel source.
Unfortunately, hydrogen can easily leak from very small cracks in a dispensing hose, particularly at the high pressures necessary for hydrogen delivery, and miniscule cracks can rapidly develop with frequent handling as found in a hydrogen fueling station. Due to such issues, high-pressure hydrogen dispensing hoses are significantly more expensive than their gasoline counterparts and replacement intervals are much shorter. Currently, the high frequency of hydrogen dispensing hose replacement results in the high-pressure hoses being a significant operations and maintenance cost to the station operator.
What are needed in the art are hydrogen dispensing hoses with increased service life. For instance, a hydrogen dispensing hose able to provide a service life beyond the current target of 1,000 fills would be of great benefit in the art.
According to one embodiment, disclosed is a multi-layer hose that includes an inner layer, an outer layer, and a self-healing layer disposed between the inner layer and the outer layer. In one embodiment, the multi-layer hose is a hydrogen dispensing hose. The self-healing layer includes a continuous fiber-reinforced composite. The continuous fiber-reinforced composite includes a continuous core fiber and a self-healable matrix formulation on the continuous core fiber. The self-healable matrix formulation includes a self-healing copolymer. The continuous core fiber can be a polymeric fiber, e.g., a single filament or multi-filament tow or roving.
Also disclosed is a method for forming a multi-layer hose. A method can include locating a self-healable matrix formulation on a continuous core fiber to form a continuous fiber-reinforced composite, the self-healable matrix formulation including a self-healing copolymer. The method can also include forming a self-healing layer that incorporates the continuous fiber-reinforced composite via, e.g., winding, weaving, or braiding of the composite. A method can also include locating the self-healing layer between an inner layer and an outer layer to form a multi-layer hose.
A full and enabling disclosure of the present subject matter, including the best mode thereof to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures in which:
Reference will now be made in detail to various embodiments of the disclosed subject matter, one or more examples of which are set forth below. Each embodiment is provided by way of explanation of the subject matter, not limitation thereof. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made in the present disclosure without departing from the scope or spirit of the subject matter. For instance, features illustrated or described as part of one embodiment, may be used in another embodiment to yield a still further embodiment.
In one embodiment, disclosed is a multi-layer hose that can include a self-healing layer that includes a continuous fiber-reinforced composite. The continuous fiber-reinforced composite includes a core fiber and a self-healable matrix formulation on the core fiber. The self-healable matrix formulation includes a self-healing copolymer. Also disclosed are methods for forming a continuous fiber-reinforced composite.
A multi-layer hose can include a self-healing layer sandwiched between an inner layer and an outer layer of the multi-layer hose. In one particular embodiment, a multi-layer hose can be a hydrogen dispensing hose. A hydrogen dispensing hose including one or more self-healing layers can exhibit extended service life as compared to previously known hydrogen dispensing hoses. For example, a hydrogen dispensing hose including one or more self-healing layers as described herein can exhibit a service life of about 1,000 uses or more, such as about 10,000 uses or more, about 20,000 uses or more, or about 25,000 uses or more in some embodiments. Moreover, a hydrogen dispensing hose can exhibit long service life under all manner of expected conditions, including high pressure conditions and/or extreme temperature conditions. For instance, disclosed hydrogen dispensing hoses can maintain structural integrity and exhibit self-healing under pressures of about 345 kPa (about 50 psi) or greater, such as about 400 kPa or greater, or about 500 kPa or greater in some embodiments, and can exhibit long service life and self-healing properties in temperatures ranging from about-40° C. to about 85° C. and as such can be useful in a wide variety of environments.
A continuous fiber-reinforced composite can include a continuous core fiber and a self-healable matrix formulation thereon, the self-healable matrix formulation including a self-healing copolymer. Self-healing copolymers as may be utilized in forming the continuous fiber-reinforced composite have been described, for instance in U.S. Pat. No. 11,312,807 to Urban, which is incorporated herein by reference for all purposes. Self-healing copolymers encompass those for which a structure (e.g., a film) formed of the copolymer can exhibit self-healing properties following damage, e.g., a tear, a break, a scratch, etc. In some embodiments, a self-healing copolymer can continue to exhibit self-healing properties following multiple damage cycles, such as about 1000 damage-repair cycles or more, and for which mechanical properties, e.g., stress at break and/or maximum elongation, following 1000 damage cycles can be about 70% or more of the values prior to any damage being inflicted on the structure, such as about 75% or more, such as about 80% or more, or about 85% or more in some embodiments.
In one embodiment, a self-healing copolymer include an alkyl methacrylate component and an alkyl acrylate component. In one embodiment, a self-healing copolymer can include units derived from an alkyl methacrylate monomer having an alkyl group of 1-6 carbons and units derived from an alkyl acrylate monomer having an alkyl of 2 to 8 carbons. Examples of alkyl methacrylate monomers as may be incorporated in a self-healing copolymer can include, without limitation, methyl methacrylate (MMA), 2,2,2-Trifluoroethyl methacrylate (TFEMA), 2,2,3,3,4,4,4-Heptafluorobutyl methacylate (HFBMA), 1,1,1,3,3,3hexafluoroisopropyl methacrylate (HFiPMA), or any combination thereof. Examples of alkyl acrylate monomers as may be incorporated in a self-healing copolymer can include, without limitation, n-butyl acrylate (nBA), n-pentyl acrylate (nPA), hexyl acrylate (HA), n-butyl acrylate (nBA), or any combination thereof.
The molar ratio of alkyl methacrylate monomers to alkyl acrylate monomers utilized in forming a self-healing copolymer can be varied from about 45/55 to about 55/45, or about 50/50 molar compositional range in some embodiments. As illustrated in
While not limited to any particular theory, it is understood that the pendant groups of adjacent units of a self-healing copolymer can form an inter-pendant space with a volume of about from about 80 cubic Angstroms (Å3) to about 140 Å3, for instance from about 110 Å3 to about 130 Å3, such as about 120 Å3 in one embodiment. As illustrated in
Any suitable copolymerization technique, e.g., statistical, ATRP, RAFT, colloidal, can be employed to form a self-healable copolymer, provided that the copolymer topologies are predominantly alternating/random and that the monomer molar ratios are from about 45/55 to about 55/45, as previously stated.
The molecular weight of the copolymers is not particularly limited. By way of example, copolymers formed according to an ATPR formation process can exhibit a number average molecular weight of about 25 kD, while copolymers formed according to a statistical free radical process can exhibit a molecular weight of about 60 kD, and those prepared by colloidal methods can exhibit a molecular weight of about 700 kD. Table 1, below, presents examples of p (MMA/nBA) self-healing copolymers as may be utilized in forming products as disclosed herein.
As schematically illustrated in
Beneficially, structures formed of a self-healable matrix formulation can exhibit desirable mechanical properties both prior to and following self-healing and as such can be well-suited for inclusion in a multi-layer hydrogen dispensing hose. By way of example, a film formed solely of a self-healing copolymer can exhibit a tensile strain of about 400% or greater, about 500% or greater, or about 550% in some embodiments. A film formed solely of a self-healing copolymer can exhibit a stress value of about 8 MPa or greater, such as about 8.5 MPa or greater in some embodiments.
A self-healable matrix formulation can include one or more self-healing copolymers in conjunction with one or more additional components as are known in the art, e.g., additives such as, and without limitation to, antimicrobials, lubricants, pigments or other colorants, antioxidants, stabilizers (e.g., UV stabilizers and/or heat stabilizers), surfactants, flow promoters, fillers, etc., and other additives as are known in the art as may be utilized to enhance properties and processability of a formulation. Such optional materials may be employed in a self-healable matrix formulation in conventional amounts such that they do not affect the self-healing properties of the formulation. For instance, a self-healable matrix formulation can generally include one or more self-healing copolymers in an amount of from about 80 wt. % to 100 wt. %.
A continuous fiber-reinforced composite can include a self-healable matrix formulation as a layer on a surface of a core continuous fiber. As utilized herein, the term “continuous fiber” is intended to refer to a fiber that is characterized as having a very high length to diameter ratio, e.g., about 100 or greater, and is generally differentiated from chopped or short fibers, such as those utilized as fillers.
While a continuous fiber-reinforced composite can incorporate any continuous core fiber as is known in the art, in particular embodiments the continuous core fiber can be a high strength copolymer continuous fiber. The continuous core fiber can include an individual filament or a plurality of individual filaments, e.g., a roving. As used herein, the term “roving” generally refers to a bundle of generally aligned individual filaments and is used interchangeably with the term “tow.” The individual filaments contained within the roving can be twisted or can be straight and the bundle can include individual filaments twisted about one another or generally parallel continuous filaments with no intentional twist to the roving. Although different filaments can be used in a roving, it can be beneficial in some embodiments to utilize a roving that contains a plurality of a single filament type, for instance to minimize any adverse impact of using filament types having a different thermal coefficient of expansion. The number of filaments contained in a roving can be constant or can vary from one portion of the roving to another and can depend upon the material of the fiber. A roving can include, for instance, from about 500 individual filaments to about 100,000 individual filaments, or from about 1,000 individual filaments to about 75,000 individual filaments, and in some embodiments, from about 5,000 individual filaments to about 50,000 individual filaments. Of course, bundles of individual filaments as may be utilized as a core continuous fiber can include fewer filaments, e.g., from only a few filaments to several hundred filaments, e.g., from about 5 individual filaments to about 500 individual filaments, or from about 30 individual filaments to about 200 individual filaments in some embodiments.
A continuous core fiber can possess a high degree of strength and tenacity. For example, a continuous core fiber can exhibit a modulus as determined according to ASTM D2256-02 of about 8 GPa or greater, such as about 10 GPa or greater, about 12 GPa or greater, or about 16 GPa or greater in some embodiments. In addition, a core fiber can have a high tenacity as determined according to ASTM D2256-02 of about 400 MPa or greater, such as about 500MP or greater, or about 560 MPa or greater in some embodiments. A continuous core fiber can also have a low density, such as about 1.3 g/cm3 or less, such as about 1.0 g/cm3 or less in some embodiments.
A continuous core fiber may be a polymeric fiber. For example, a continuous filament may include a polyolefin (e.g., a high performance multi-filament olefin yarn such as those marketed by Innegra™ of Colfax, NC), a polyaramid (e.g., Kevlar® marketed by E. I. duPont de Nemours, Wilmington, Del.), a polyamide, an ultra-high molecular weight polyethylene, a polyphenylene sulfide, a polybenzimidazole (PBI), or other natural or synthetic inorganic or organic materials known for forming continuous fibers. A core fiber can optionally include one or more additives as are known in the art in conjunction with the polymer, e.g., colorants, plasticizers, etc.
In one embodiment, a continuous core fiber can have a nominal diameter of about 2 micrometers or greater, for instance about 4 to about 35 micrometers, and in some embodiments, from about 5 to about 35 micrometers.
Referring to
The solution 2 can include a solvent for the self-healing copolymer(s), and can encompass organic or aqueous solvents and a self-healable copolymer. A preferred solvent can generally be determined according to the characteristics of the copolymer. Exemplary solvents can include, and without limitation to, methanol, ethanol, or chloroform. The solution 2 can generally include the copolymer(s) in an amount of about 20 wt. % or less, about 10 wt. % or less, or about 5 wt. % or less in some embodiments. For instance, the solution 2 can include one or more self-healable copolymers in an amount of from about 0.3 wt. % to about 5 wt. % or from about 0.3 wt. % to about 3 wt. % in some embodiments.
As illustrated in
A continuous fiber-reinforced composite 18 can then be wound, braided, woven, or otherwise formed to provide a self-healing layer. For example, as illustrated in
A self-healing layer 20 may include one or more sub-layers within an individual layer 20. For instance, a self-healing layer may include multiple individual braided, woven or wrapped continuous fiber-reinforced composites or layers thereof to optimize the balance of fiber orientations and strength throughout a self-healing layer 20. A self-healing layer 20 may be formed as a flat sheet and then shaped to form the self-healing layer 20 or alternatively may be formed directly in the final shape/size of the self-healing layer 20 of a hose 28. Moreover, while illustrated with a generally cylindrical shape, a hose 28 can have any desired cross-section shape and size.
A formation method can provide for an orientation direction of the continuous fiber-reinforced composite(s) 18 of the self-healing layer 20 to be tailored to the location and geometry of the contour of a hose 28, for instance to optimize load bearing. By way of example, continuous fiber-reinforced composites 18 may be woven or wrapped at +45° with reference to the longitudinal axis of the hose 28 to form a self-healing layer 20. In some embodiments, a self-healing layer 20 can include multiple layers that are oriented at an angle to one another as well as to the longitudinal axis of the hose 28. With respect to cylindrical hoses, loads are mainly hoop loads on the order of pressure multiplied by radius over thickness (PR/T) and axial loads on the order of PR/2T. A beneficial fiber orientation in a hose section may therefore in one embodiment include one portion of axial fibers and two portion of hoop fibers (as hoop loads are on the order of twice axial loads in magnitude), and further, in which each portion of hoop fibers are oriented at an angle to one another as well as to the longitudinal axis of the hose 28. Additional hoop fibers or axial fibers may be added in order to optimize hoop and axial strength. Toward an end portion of a hose, additional off-axis fibers may be provided or implemented to accommodate for the complex stress regions of an end portions.
The orientations of continuous fiber-reinforced composites may differ along the length of a hose 28 depending on structural needs imposed by the geometry and depending on the material (e.g., hydrogen) to be delivered through the hose 28. For instance, a continuous fiber-reinforced composite can be wound, woven, or braided such that the fiber is at any angle to the axis of a hose, including aligned therewith. By way of example, a continuous fiber-reinforced composite 18 can be at an angle to a hose axis of about 15°, about 20°, about 25°, about 30°, about 40°, about 45°, about 50°, about 55°, about 60°, about 65°, about 70°, about 75°, about 80°, about 85°, or about 90°, or any combination thereof. Moreover, a continuous fiber-reinforced composite can be combined with other fibers which can be the same or different from one another and the continuous fiber-reinforced composites at the same or different orientations and can be modified in orientation throughout the depth or length of a self-healing layer 20. As such, in one embodiment, a self-healing layer 20 may be formed on a mandrel which enables an evolving fiber orientation.
A self-healing layer formed of a continuous fiber-reinforced composite can retain desirable mechanical properties following a plurality of damage/repair cycles. For instance, following 10,000 damage-repair cycles of a spiral wound self-healing layer, mechanical properties of the layer such as ultimate strength and Young's modulus can be about 85% or greater as compared to the pre-damaged values of the layer. In one embodiment, a cylindrical structures formed of a continuous fiber-reinforced composite as may be utilized as a self-healing layer in a hose can exhibit about 95% or more, such as about 97% or more of the original, pre-damaged value of elastic modulus, normal strain, and Young's modulus following 10,000 damage-repair cycles. Moreover, certain mechanical characteristics, such as ultimate strength and strain at break of a self-healing layer can be essentially the same (i.e., within 3%) as the original value prior to any damage.
A hydrogen dispensing hose that includes a self-healing layer as described can include the self-healing layer sandwiched within an interior of a multilayer hose. For instance, as illustrated in
An inner layer 22 can be of any size. For instance, when considering formation of a hydrogen dispensing hose for use as a fuel line, an inner layer 22 can typically have an outer diameter of about 50 mm or greater, such as from about 50 mm to about 100 mm. It is to be understood that various outer diameter may be produced as desired or required. In some embodiments, an inner layer 22 can have a thickness of from about 0.1 mm to about 5 mm, such as from about 0.5 mm to about 4 mm, such as from about 1 mm to about 3 mm in some embodiments.
An inner layer 22 can generally be formed of a polymeric formulation and may be based upon either thermoplastic or thermoset polymers as desired or required. An inner layer 22 may be a single polymeric layer or may be composed of multiple layers. Examples of polymers as may be utilized in forming an inner layer 22 can include, without limitation, polyoxymethylene; fluoropolymers such as polyvinylidine fluoride, polyvinyl fluoride, polychlorotrifluoroethylene, ethylene tetrafluoroethylene copolymers, polytetrafluoroethylene (PTFE); polyamides; polyesters; polyarylene sulfides; ethylene vinyl alcohols (EVOH); polyolefins, such as a silane crosslinked or acid- or hydroxyl-modified polyethylene resin; a polyethylene terephthalate (PET); a polybutylene terephthalate (PBT); or thermoplastic elastomers; as well as blends, copolymers, or any combination thereof. Examples of polyamide thermoplastics include, without limitation, polyamide 12, polyamide 11, polyamide 6, and polyamide 6.6. Suitable polyarylene sulfides typically have a polymer backbone composed of a series of alternating aromatic rings and sulfur atoms, The aromatic rings are typically di-substituted in the para position and the sulfur atoms are present as divalent moieties.
An inner layer 22 may be formed by any suitable method such as by extruding a suitable material in an appropriate extrusion process, by paste extrusion process, or by electrostatic powder coating as is known in the art.
A hydrogen dispensing hose 28 may also include an outer layer 24, which is positioned radially outward from the inner layer 22 and the self-healing layer 20 in overlying relationship thereto. The outer layer 24 may be a single layer or may be composed of several individual concentric layers. In one embodiment, the outer layer 24 can be a melt-processible thermoplastic polymer formulation that can be relatively resistant to interaction with the external environment.
An outer layer 24 may be formed of the same or different materials as the inner layer 22. In one embodiment, an outer layer 24 can include a polyamide or appropriate melt-processible thermoplastic elastomer, such as, and without limitation to, polyamide 12, polyamide 11, polyamide 6, and polyamide 6.6.
An outer layer 24 can generally have a thickness suitable for reinforcement and cushioning of the hose construction. In some embodiments, an outer layer 24 can have a thickness of from about 0.1 mm to about 5 mm, such as from about 0.5 mm to about 4 mm, such as from about 1 mm to about 3 mm in some embodiments.
A multi-layer hose can include one or more additional layers, in addition to an inner layer 22, a self-healing layer 20, and an outer layer 24. By way of example,
The present invention may be better understood with reference to the examples set forth below.
Films formed of self-healing p (MMA/nBA) copolymers including an MMA/nBA ratio of 46/54 and 53/47 were subjected to mechanical damage and the films were allowed to self-heal ambient environments for 14 h. Tensile testing was carried out before damage and after the 14 h self-repair to determine self-healing efficiency. As illustrated in
Continuous fiber-reinforced composites were formed including polypropylene core fiber available from Innegra™ and a p (MMA/bNA) copolymer with a 47:53 molar ratio on the core fiber. An X-winder apparatus (filament winder) was used to form self-healable hose layers with desirable diameters and length.
Multiple sample hoses were formed. Table 2, below, provides results for 5 different samples of a 3-layer hose design. As indicated, the samples demonstrated highly consistent dimensions.
Hoses were tested for tensile characteristics.
Samples were also subjected to shelf-life testing that includes a temperature loop of −196° F. (2 h)→85° C. (2 h)→−196° C. (2 h)→85° C. (2 h)→25° C. (12 h) for 10 consecutive loops.
Three hoses were formed and stress-strain characteristics compared. All three hoses were formed of continuous fiber-reinforced composites including a polypropylene core Innegra™ fiber. The self-healing copolymers utilized in forming the continuous fiber-reinforced composites included a high molecular weight p (MMA/nBA) copolymer synthesized by emulsion copolymerization, a TFEMA/nBA copolymer synthesized by free radical polymerization, and a p (MMA/nBA) copolymer synthesized by free radical polymerization. All hoses were formed with a 45° winding angle and three layers of the wound continuous fiber-reinforced composite. The stress-strain curves for the formed hoses are shown in
Two Independent 10,000 damage-repair cycle tests were carried out on films formed of p (MMA/nBA) copolymers. Both copolymers had a 47/53 MMA/nBA ratio. One of the copolymers had a number average molecular weight (Mn) of 30 kDa, and the other had a Mn of 50 kDa. The testing included a damage cut followed by a repair period, and the cycle was repeated 10,000 times.
10,000 Damage-Repair (Bend-Release) Cycle Tests were carried out with hoses formed of continuous fiber-reinforced composites. The continuous fiber-reinforced composites used included a core fiber of a polypropylene core Innegra™ fiber and a 50 kDa p (MMA/nBA) copolymer. Three layers of fibers were utilized in forming the hoses.
Cycle tests were conducted using a robotic arm. Each hose was bent and released 10,000 times. Following, areas where bending occurred were cut off from each hose and tensile tests were conducted. An undamaged section of each hose was used as a control.
While certain embodiments of the disclosed subject matter have been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the subject matter.
This application claims filing benefit of U.S. Provisional Patent Application Ser. No. 63/504,011 entitled “Self-Healing Hydrogen Dispensing Hose and Process of Manufacture,” having a filing date of May 24, 2023, which is incorporated herein by reference for all purposes.
This invention was made with Government support under Grant No. DE-EE0008827, awarded by the Department of Energy. The Government has certain rights in the invention.
| Number | Date | Country | |
|---|---|---|---|
| 63504011 | May 2023 | US |
