Multilayer structures and articles for the storage and transportation of gases

Abstract

Disclosed herein are multilayer structures comprising thermoplastic composite materials. The thermoplastic composite materials comprise continuous fibers and a polymer matrix comprising a poly(arylene sulfide) (PAS) polymer, a polyetherimide (PEI) polymer, and, optionally, a polyamide-imide (PAI) polymer.

Description

MULTILAYER STRUCTURES AND ARTICLES FOR THE STORAGE AND TRANSPORTATION OF GASES CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] TThis application claims priorities filed on 2024 September 12 in the United States of America with Nr 63 / 694030 and on 2024 October 25 in Europe with Nr.24208992.8, the whole content of each of these applications being incorporated herein by reference for all purposes. Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence. FIELD OF THE DISCLOSURE

[0002] The invention relates to thermoplastic composite materials provided with excellent mechanical properties, interfacial adhesion, and low hydrogen permeation. This combination of properties makes these materials suitable for the manufacture of articles adapted for the storage and transportation of gases, in particular hydrogen, the storage and transportation of cryo compressed gases such as hydrogen and the storage and transportation of liquids, such as hydrogen. The invention further relates to the articles, such as pressure vessels, comprising the thermoplastic composite material. BACKGROUND

[0003] To achieve levels of decarbonisation required to meet the Intergovernmental Panel on Climate Change target of preventing global warming greater than 1.5 °C above pre-industrial levels, strong global action to reduce carbon emissions is being undertaken. Hydrogen, in particular the so-called “green hydrogen”, that is hydrogen produced using clean energy sources, as an energy carrier has been identified as suitable for meeting these climate objectives. A key challenge to enabling the use of hydrogen, particularly in weight-critical aerospace and automotive environments, is storing it with high volumetric and gravimetric density.

[0004] Despite its popularity, the storage of hydrogen as a gas is challenging as it is the lightest element and must be held at very high pressure (i.e., 350–700 bar) to achieve practical densities.The storage or transportation of large volumes of highly compressed hydrogen requires a shift from the use of metal containers or piping to lighter materials, such as polymeric materials. Tanks comprising composite materials is an area of significant interest due to the potential for high strength, low weight, and corrosion resistance offered by these materials. The same holds true for storage and transportation of liquid hydrogen and cryo compressed hydrogen

[0005] Composite materials typically consist of a polymer matrix (a continuous phase) and a dispersed phase of continuous fibers that provide reinforcement. For hydrogen storage tanks, these materials must satisfy several key properties.

[0006] Mechanical Strength and Durability: The tank must withstand high pressures required for hydrogen storage (often in the range of 350-700 bar) without failure over its operational life.

[0007] Lightweight: To maximize the efficiency of hydrogen storage, especially for mobile applications like vehicles, the tanks must be as light as possible without compromising safety or performance.

[0008] Thermal Stability: During the filling and release of hydrogen, the tank will experience changes in temperature. The materials must maintain their integrity and performance characteristics over a wide range of temperatures, for instance, from - 65 °C to 100 °C for large tanks for compressed hydrogen.

[0009] Permeability: the composite material need minimize hydrogen permeation to prevent leaks, which could pose safety risks and reduce the efficiency of storage.

[0010] Durability and permeability for storing and transporting liquid hydrogen: the tank must withstand large temperature cycles from room temperature down to - 252.8 °C for liquid hydrogen and down to - 233°C for cryo compressed hydrogen.

[0011] Pressure vessels characterized by high gas barrier properties have been used for storing various gasses such as oxygen, carbon dioxide, nitrogen, argon, LPG (liquefied petroleum gas), methane, hydrogen, over a long period of time. Pressure vessels comprising a non-structural inner layer or liner surrounded with a structural fiber reinforced composite material for containing the fluid or gas under pressure are known. The liner acts as a barrier between the fluid or gas and the fiber reinforced composite material, thus preventing leaks and / or other degradations of the structure of the fiber reinforced composite material.

[0012] Composite materials typically include structural reinforcing fibers embedded in a polymer matrix. Composite materials have been employed in a wide variety of applications. For example,continuous fiber composites have been used to form fiber reinforced composite tapes, ribbons, rods, prepregs, laminates, and profiles useful as lightweight structural reinforcements as well as protective casings. Composite materials comprising a thermoplastic polymer matrix are known to offer a number of benefits over thermosetting based materials. For example, thermoplastic prepregs can be more rapidly fabricated into articles. Another advantage is that thermoplastic articles may be recycled.

[0013] The need still exists to develop articles for the transport and storage of hydrogen and gasses in general, in particular pressure vessels, which combine high performance qualities in terms of impermeability to the stored gas, mechanical properties, at both low and high temperature, and high thermal degradation temperature, for ease of processing.

[0014] The objective of the invention is thus providing articles, such as pressure vessels, having very low permeability to gasses, such as hydrogen, and good mechanical resistance over a wide range of temperatures without requiring the use of structural layers made of metal or other non- thermoplastic polymeric materials. The objective is achieved by the thermoplastic composite material of the invention. The inventors have found that a good compromise between permeability to hydrogen, good mechanical properties and increased interfacial adhesion can be obtained by a vessel comprising a thermoplastic composite material as defined in the appended claims. BRIEF SUMMARY

[0015] A first object of the invention is thus a multilayer structure comprising the presently disclosed thermoplastic composite materials. The multilayer structure is suitable for use in a large number of demanding applications, in particular in the preparation of articles for storing or transporting a gas or a liquid or a cryo compressed gas comprising at least one layer made of the thermoplastic composite material of the invention. The article may be a vessel, preferably a pressure vessel, that is a vessel for the storage of a gas or a liquid or a cryo compressed gas under pressure. The thermoplastic composite material comprises continuous reinforcing fibers and a polymer matrix, said polymer matrix comprising: a poly(arylene sulfide) (PAS) polymer, a polyetherimide (PEI) polymer, and a polyamide-imide (PAI) polymer. The PEI polymer is present in an amount from 1.0% to 50% by weight, and the PAI polymer is present in an amount from 0.0% to 5% by weight, both weights being based on the total weight of the polymer matrix.

[0016] The continuous reinforcing fibers are advantageously carbon fibers.

[0017] A second object of the invention is a compressed gas or a liquid or a cryo compressed gas in a vessel comprising at least one layer made of the thermoplastic composite material of the invention. The compressed gas may be in direct contact with the layer made of the thermoplastic composite material of the invention. Further objects of the invention are a method for making the composite material as well as the article. DETAILED DESCRIPTION

[0018] In the present application, any description, even if described in relation to a specific embodiment, is applicable to and interchangeable with other embodiments of the present disclosure, and each embodiment thus defined may be combined with another embodiment, unless otherwise indicated or clearly incompatible.

[0019] Where an element or component is said to be included in and / or selected from a list of recited elements or components, it should be understood that in related embodiments explicitly contemplated here, the element or component can also be any one of the individuals recited elements or components, or can also be selected from a group consisting of any two or more of the explicitly listed elements or components; any element or component recited in a list of elements or components may be omitted from such list.

[0020] Any recitation herein of numerical ranges by endpoints includes all numbers subsumed within the recited ranges as well as the endpoints of the range and equivalents.

[0021] The term “comprising” (or equivalents) includes “consisting essentially of,” and also “consisting of.”

[0022] As used herein, the term “consisting essentially of” or “essentially consisting” indicates that the referred to composition contains less than 5 wt%, typically less than 2 wt% or less than 1 wt%, of any other ingredient.

[0023] The use of the singular “a” or “one” herein includes the plural unless specifically stated otherwise.

[0024] It should be understood that the elements, properties, and / or the characteristics of a (co)polymer, product or article, a process, or a use, described in the present specification, may be combined in all possible ways with the other elements, properties and / or characteristics of the(co)polymer, product or article, process or use, explicitly or implicitly, this being done without departing from the scope of the present description.

[0025] Should the disclosure of any patents, patent applications, and publications that are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

[0026] A first object of the invention is thus a multilayer structure comprising the presently disclosed thermoplastic composite materials. The multilayer structure is suitable for use in a large number of demanding applications, in particular in the preparation of articles for storing or transporting a gas comprising at least one layer made of the thermoplastic composite material of the invention. The article may be a vessel, preferably a pressure vessel, that is a vessel for the storage of a gas under pressure. The thermoplastic composite material comprises continuous reinforcing fibers and a polymer matrix, said polymer matrix comprising: a poly(arylene sulfide) (PAS) polymer, a polyetherimide (PEI) polymer, and a polyamide-imide (PAI) polymer. The PEI polymer is present in an amount from 1.0% to 50% by weight, and the PAI polymer is present in an amount from 0.0% to 5% by weight, both weights being based on the total weight of the polymer matrix.

[0027] The Multilayer Structure

[0028] An object of the invention is a multilayer structure comprising a thermoplastic composite material.

[0029] The multilayer structure comprises two, three, four, five, six, seven, eight, nine, ten, 50, 80, 100 or even more layers consisting of the thermoplastic composite material, such as 200 or 300 layers.

[0030] The multilayer structure may additionally comprise one or more layers that are free of continuous reinforcing fibers. The additional layers may or may not comprise a poly(arylene sulfide) polymer. Preferably, the additional layers are not made of metallic strips of material.

[0031] The inventive multilayer structure is characterized by high thermal resistance, good hydrogen barrier, low transverse cracking and non-flammability. These features make the multilayer structure particularly well adapted for a wide range of demanding applications.

[0032] The multilayer structure is preferably an article for storing or transporting a gas or a liquid or a cry compressed gas, the article comprising at least one layer made of the thermoplastic composite material. The thermoplastic composite material of the present invention, thanks to itsexcellence in both flexibility and reduced hydrogen permeability, is suitable for use as a component in an article for the storage or transportation of compressed gas, in particular hydrogen, liquid hydrogen, or cryo compressed hydrogen. Notable non-limiting examples of articles are hoses, pipes, tubes, joints, tanks, reservoirs or, in general, vessels.

[0033] The hose for compressed hydrogen is used as a hose for charging a fuel-cell vehicle or the like with hydrogen from a hydrogen station. Since the hose for compressed hydrogen is subject to repeated temperature changes (heat cycles) from -40°C or lower to 90°C or higher due to charging and discharging of high-pressure hydrogen, it is required to have high heat cycle resistance, pressure cycle resistance as well as flexibility.

[0034] The hose for high-pressure hydrogen is a hose comprising or consisting of the multilayer structure as above defined.

[0035] The article may be a vessel, preferably a pressure vessel, that is a vessel for the storage of a gas or a liquid or a cryo compressed gas under pressure.

[0036] The term “vessel” is used herein to refer to a hollow container or any system for the transportation of a fluid, in particular a pressurized gas. The vessel of the invention can be a hollow container for containing a gas, preferably a pressurized gas. The vessel may be a pipe, a hose or a piping system for the transportation of a gas, in particular a pressurized gas.

[0037] The vessel may consist of one or, preferably, more than one layer consisting of the thermoplastic material of the invention. Notable examples of vessels of this type are the so-called Type V or linerless vessels, that is vessels that do not have an internal liner so the composite material acts as both the gas barrier and load bearing structure.

[0038] Type V vessels mat be manufactured using filament winding, a technique that winds tensioned bands of fibres around a rotating mandrel or even by means of automated fiber placing techniques.

[0039] Alternatively, the vessel of the invention may be a Type IV vessel, that is a vessel comprising an internal barrier layer, or liner, and one or more than one layers consisting of the thermoplastic composite material of the invention. The liner forms the interior surface of the vessel, in contact with the gas. When more layers of the thermoplastic composite material are present they typically have the same composition. However, the volume % of fibers and the nature of the fibers used may vary from one layer to the next, typically from the inner to the outer surface of the vessel or between the hoop and helicoidal layers.

[0040] The vessel comprises a hollow body and at least one boss. A boss is known by a person skilled in the art and it refers to the opening in which a closure is attached which allows flow of gas or fluid in and out the vessel. A boss is usually made of metal. The boss could alternatively be made of a polymeric material, for instance a PPS.

[0041] The hollow body may have any shape suitable for the storage of a gas, in particular of a gas under pressure.

[0042] In certain conventional embodiments, the vessel has a cylindrical shape and a boss is placed at the end. Often, a vessel has two bosses at each end of the cylindrical shape.

[0043] The shape of the hollow body is determined by the desired use. It is usually but not exclusively cylindrical; it typically has a diameter of between 10.0 cm and 1.00 m.

[0044] The length of a hollow body also depends on the end use and may for example be between 50.0 cm and up to lengths as large as 10.0 m. These higher lengths are usually employed for gas transport. As an example, for vessels in trucks the length is usually between 1.0 m and 3.0 m.

[0045] The vessel of the invention may have an internal volume between 3.5 dm3and 10.0 m3, even from 5.0 dm3to 5.0 m3. The internal volume of the vessel may be at least 10.0 dm3, even at least 15.0 dm3. The internal volume may be up to 0.5 m3, even up to 1.0 m3, up to 5.0 m3, even up to 10.0 m3.

[0046] The vessel may be conformable, for instance flat to fit into the chassis of a car or conical to fit into the tail of an aeroplane.

[0047] The vessel may be prepared according to any method known in the art.

[0048] The vessel of the invention is characterized by a good hydrogen barrier and mechanical properties.

[0049] The vessel according to the invention exhibits a nominal pressure of at least 2.5 MPa, typically at least 20.0 MPa, even at least 30.0 MPa. The nominal pressure may be up to 70.0 MPa, 100 MPa, even 150.00 MPa and more. Advantageously, the vessel of the invention has a nominal pressure of 20.0 to 100.0 MPa.

[0050] A burst pressure of at least 157.5 MPa may be reached for the storage of hydrogen gas with a vessel according to the invention. Vessels for the storage of compressed hydrogen typically require nominal pressures of 35.0 MPa or 70.0 MPa. Burst pressures, measured according to ECE R134, are typically up to 78.8 MPa and 157.5 MPa, respectively.

[0051] A further object of the invention is a compressed gas in a vessel of the first object, wherein Layer (BL) is in contact with the compressed gas. The gas is advantageously selected from the group consisting of hydrogen, oxygen, nitrogen, argon, helium, methane, propane, compressed natural gas, CO2 and ammonia.

[0052] The gas is typically at a pressure of at least 5.0 MPa, preferably at least 10.0 MPa. Depending on the gas, the pressure may be up to 150.0 MPa.

[0053] A further object of the invention is a vehicle comprising the vessel or the compressed gas contained in the vessel.

[0054] The vehicle may be a car, a truck, a train, a ship, an urban mobility vehicle, an airplane, a helicopter or any other vehicle that could be powered using the conversion of a gas into energy by any means.

[0055] The Thermoplastic Composite Material

[0056] The thermoplastic composite material comprises continuous reinforcing fibers impregnated with a polymer matrix. As used herein, the expression “continuous reinforcing fiber” refers to a fiber having a length of at least 5 mm. The length of the fiber corresponds to the longest dimension of the fiber.

[0057] The continuous reinforcing fiber may have a length, in the longest dimension, of at least 1 cm, at least 25 cm or at least 50 cm. The length of the continuous reinforcing fiber is dependent on the shape and size of the finished part.

[0058] The expression “continuous fiber” is used herein also to refer to a yarn. A yarn is a continuous strand of one or more fibers, one or more filaments, or material in a form suitable for use in the production of textiles, sewing, crocheting, knitting, weaving, stitching, etc. Yarns include, for example, (1) a plurality of filaments laid or bundled together without applied or intentional twist, sometimes referred to as a zero-twist yarn or a non-twisted yarn; (2) a plurality of filaments laid or bundled together and are either interlaced, have false-twist, or are textured in some manner; (3) a plurality of filaments laid or bundled together with a degree of twist, sometimes referred to as a twisted yarn; (4) a single filament with or without twist, sometimes referred to a monofilament or monofilament yarn.

[0059] The continuous reinforcing fiber is selected from the group consisting of glass fiber, carbon fibers, aluminum fiber, metallic fibers, ceramic fiber, titanium fiber, magnesium fiber, boron carbide fibers, rock wool fiber, steel fiber, aramid fiber and natural fiber (e.g. cotton, linen andwood). Preferably, the continuous reinforcing fiber is selected from the group consisting of glass fiber, carbon fiber, aramid fiber, and ceramic fiber. Advantageously, the continuous reinforcing fiber is carbon fiber.

[0060] The thermoplastic composite material may include one or more additional continuous reinforcing fibers, each distinct in compositions and as described above.

[0061] Overall, the continuous reinforcing fibers constitute at least 5.0% of the total volume of the thermoplastic composite material. Typically the continuous reinforcing fibers represent at least 10.0%, even at least 15.0%, even at least 20.0%, at least 25.0%, even at least 30.0% of the total volume of the thermoplastic composite material. The continuous reinforcing fibers are no more than 80.0%, no more than 75.0%, even no more than 70.0% of the total volume of the thermoplastic composite material. The continuous reinforcing fibers may conveniently represent from 20.0% to 75.0%, from 25.0% to 70.0%, from 25.0% to 65.0% and even from 30.0% to 60.0% of the total volume of the thermoplastic composite material. The polymer matrix represents the remainder of the volume of the thermoplastic composite material.

[0062] The continuous reinforcing fibers in the thermoplastic composite material are generally aligned along a single direction. Generally aligned fibers are oriented such that at least 70%, at least 80%, at least 90% or at least 95% of the fibers have a direction that is within 30 degrees, within 25 degrees, within 20 degrees, within 15 degrees, or within 10 degrees along the direction of the other fibers.

[0063] The continuous reinforcing fibers in the thermoplastic composite material may be arranged at an angle the ones with respect to the others. The continuous reinforcing fibers might be arranged as a woven fabric or a layered fabric or any combination of one or more.

[0064] The thermoplastic composite material can be fabricated by methods well known in the art. In general, the method of fabrication includes a step of impregnation of the continuous reinforcing fibers with the polymer matrix, and subsequent cooling or drying to form the thermoplastic composite material.

[0065] Impregnation of the continuous reinforcing fibers with the polymer matrix may take place, for instance, by means of a melt impregnation process, which includes contacting the continuous reinforcing fibers with a melt of the polymer matrix. Subsequent to melt impregnation, the impregnated continuous reinforcing fibers are cooled to form a solid composite. Impregnation ofthe continuous reinforcing fibres with the polymer matrix may take place by means of a film infusion (double belt process).

[0066] Impregnation may take place by means of a solution process or, preferably, a slurry process. In a solution process, a solution is formed by dissolving the polymer in a liquid medium. The solution is coated onto a surface of the continuous reinforcing fibers, for example, by passing the fibers through a bath of the solution. Subsequently, the coated fibers are then heated and consolidated. In a slurry process, the continuous fibers are impregnated with particles of the polymer, for example, by passing the fibers through a suspension of the particles or a fluidized bed of the particles. Subsequently, the fibers containing the polymer particles are heated and consolidated.

[0067] The thermoplastic composite material has a thickness which is usually between 100 microns and 500 microns. The thickness is adapted to provide multilayer structures which can be easily shaped to provide an article, such as a vessel.

[0068] The Polymer Matrix

[0069] The polymer matrix comprises a binary blend of polymers. The polymers in the binary blend are a poly(arylene sulfide) (PAS) polymer and a polyetherimide (PEI) polymer. Optionally, the polymer matrix can be a ternary blend of polymers by optionally comprising a polyamide- imide (PAI) polymer. Each polymer is described in greater detail below. The PEI polymer is present in an amount from 1.0% to 50% by weight, and the PAI polymer is present in an amount from 0.0% to 5% by weight, both weights being based on the total weight of the polymer matrix.

[0070] The polymer matrix may comprise one or more additives commonly employed in the formulation of poly(arylene sulfide) polymers. Non limiting examples of suitable additives are antioxidants (e.g., ultraviolet light stabilizers and heat stabilizers), processing aids, nucleating agents, lubricants, flame retardants, smoke-suppressing agents, anti-static agents, anti-blocking agents, colorants, and pigments.

[0071] Processing aids aid to reduce the viscosity and melt flow rate to improve impregnation of the fibers (discussed in detail below). Desirable processing aids include organic substances having a molecular weight of from 100 g / mol to 1,000 g / mol, including, but not limited to, a paraffin, an olefin, an olefin oligomer, an alkoxylated acyclic carboxylic acid, an alkoxylated acyclic carboxylic acid, amide, an acyclic carboxylic acid, an acyclic carboxylic acid ester, an acyclic carboxylic acid alkali metal salt, an acyclic carboxylic acid amide, an alkoxylated acyclic alcohol,an acyclic alcohol, an alkoxylated alkyl phenol, an alkyl phenol, and any combination of two or more thereof. Particularly desirable combinations of processing aids include, but are not limited to, paraffin and a sterically hindered phenolic stabilizer. In some embodiments, the concentration of the processing aid is from 0.05 wt.% to 1 wt.%, from 0.05 wt.% to 0.5 wt.% or from 0.1 wt.% to 0.5 wt.%. For clarity, in embodiments including a combination of processing aids, the concentration of each processing aid or the total concentration of all processing aids is within the previously described ranges.

[0072] The polymer matrix may be free of additional components or processing aids. In such embodiments, the total concentration of the additional components, processing aids, or both in the polymer matrix is no more than 1 wt.%, no more than 0.5 wt.%, no more than 0.1 wt.%, no more than 0.05 wt.%, or no more than 0.01 wt.%, no more than 0.005 wt.% or no more than 0.001 wt.%.

[0073] The total amount of additives may be 20.0 wt% or less, even 10.0 wt% or less with respect to the total weight of the polymer matrix. When present the amount of one or more additives is at least 1.0 wt%, even at least 2.0 wt%, relative to the total weight of the polymer matrix.

[0074] The Poly(Arylene Sulfide) (PAS) Polymer

[0075] The presently disclosed polymer matrix comprises a poly(arylene sulfide) (PAS) polymer. As used herein, a poly(arylene sulfide) polymer refers to any polymer including at least 50 mol% of a recurring unit (RPAS) having the following formula: -[-Ar-S-]-, where Ar is an arylene. The PAS polymer can have at least 60 mol%, at least 70 mol%, at least 80 mol%, at least 90 mol%, at least 95 mol%, at least 99 mol% or at least 99.9 mol% of recurring unit (RPAS).

[0076] The recurring unit (RPAS) is represented by a formula selected from the following group of formulae:where R, at each instance, is independently selected from the group consisting of a C1-C12 alkyl group, a C7-C24 alkylaryl group, a C7-C24 aralkyl group, a C6-C24 arylene group, and a C6-C18 aryloxy group; T is selected from the group consisting of a bond, –CO-, -SO2-, -O-, -C(CH3)2, phenyl and -CH2-; k, at each instance, is an independently selected integer from 0 to 4; and l, at each instance, is an independently selected integer from 0 to 3.

[0077] Alternatively, or in addition, k and l, at each instance, is zero. Preferably, -Ar- is represented by either Formula (1) or (2), more preferably Formula (1) (recurring unit (RPAS) corresponding to recurring units of polyphenylene sulfide), still more preferably, recurring unit (RPAS) is represented by the following formula:

[0078] The concentration of recurring unit (RPAS) in the PAS polymer is at least 50 mol%, at least 60 mol%, at least 70 mol%, at least 80 mol%, at least 90 mol%, at least 95 mol%, at least 98 mol%, at least 99 mol% or at least 99.9 mol%.

[0079] According to an embodiment of the present invention, the PAS polymer is such that about 100 mol. % of the recurring units are recurring units of Formula 1. According to this embodiment, the PAS polymer consists essentially of recurring units (RPPs) of Formula 1.

[0080] Suitable examples of a PAS polymer as described above include, but are not limited to, poly(2,4-toluene sulfide), poly(4,4'-biphenylene sulfide), poly(phenylene sulfide) including poly(para-phenylene sulfide) (PPS), poly(ortho-phenylene sulfide), poly(meta-phenylene sulfide), poly(xylene sulfide), poly(ethylisopropylphenylene sulfide), poly(tetramethylphenylene sulfide), poly(butylcyclohexylphenylene sulfide), poly(hexyldodecylphenylene sulfide),poly(octadecylphenylene sulfide), poly(phenylphenylene sulfide), poly-(tolylphenylene sulfide), poly(benzylphenylene sulfide) and poly[octyl-4-(3-methylcyclopentyl) phenylene sulfide].

[0081] The PAS polymer can have a weight average molecular weight (“Mw”) of at least 10,000 g / mol, at least 20,000 g / mol, at least 25,000 g / mol, at least 30,000 g / mol, or at least 35,000 g / mol. In some embodiments, the PAS polymer has an Mw of no more than 150,000 g / mol, no more than 100,000 g / mol, no more than 90,000 g / mol, no more than 85,000 g / mol, or no more than 80,000 g / mol. In some embodiments, the PAS polymer has an Mwof from 10,000 g / mol to 150,000 g / mol, from 20,000 g / mol to 100,000 g / mol, from 25,000 g / mol to 90,000 g / mol, from 30,000 g / mol to 85,000 g / mol, or from 35,000 g / mol to 80,000 g / mol. Mwcan be measured with gel permeation chromatography (“GPC”) using a 4-chloronapthalene standard.

[0082] The PAS polymer can be semi-crystalline. The person of ordinary skill in the art will recognize that when a polymer is amorphous, it lacks a detectable Tm. Accordingly, when a PAS polymer has a Tm, the person of ordinary skill in the art will recognize that it refers to a semi- crystalline polymer. The PAS polymer can also have a ΔHf of at least 10 J / g, at least 20 J / g, at least, or at least 25 J / g. Alternatively, or in addition, the PAS polymer can have a ΔHf of no more than 90 J / g, no more than 70 J / g or no more than 60 J / g. The PAS polymer can have a ΔHfof from 10 J / g to 90 J / g or from 20 J / g to 70 J / g.

[0083] The PAS polymer can have a melting temperature (“Tm”) of at least 200 ℃, at least 220 ℃, at least 240 ℃, or at least 250 ℃. Alternatively, or in addition, the PAS polymer can have a Tmof no more 350 ℃, no more than 320 ℃, no more than 300 ℃, or no more than 285 ℃. The PAS polymer can have a Tm of from 200 ℃ to 350 ℃, from 220 ℃ to 320 ℃, from 240 ℃ to 300 ℃, or from 250 ℃ to 285 ℃.

[0084] It will be understood that the arylene groups of the PAS polymer can be substituted or unsubstituted.

[0085] Additionally, the PAS polymer can include any isomeric relationship of the sulfide linkages in polymer; e.g., when the arylene group is a phenylene group, the sulfide linkages can be ortho, meta, para, or combinations thereof.

[0086] The PAS polymer of the present disclosure can be obtained by a process known in the art. Reference can notably be made to WO 2015 / 095362 (Chevron Philipps), WO 2015 / 177857 (Solvay) and WO 2016 / 079243 (Solvay).

[0087] The PAS polymer typically represents the balance to 100 wt% in the polymer matrix. The poly(arylene sulfide) polymer is generally at least 50.0 wt% of the polymer matrix, even at least 55.0 wt%, typically at least 60.0 wt%, or even at least 70.0 wt%.

[0088] The Polyetherimide (PEI) Polymer

[0089] The presently disclosed polymer matrix comprises a polyetherimide (PEI) polymer. The PEI polymer can be an aromatic PEI polymer.

[0090] As used herein, a polyetherimide (PEI) denotes any polymer of which more than 50 mol % of recurring units (RPEI) are selected from the group consisting of units of formulae :and combinations thereof, where : each B, equal to or different from each other, is independently selected from group consisting of –O– and –O–Ar–O–, where Ar is selected from the group consisting of moieties of formulae :where each R, equal or different from each other, is independently selected from the group consisting of hydrogen, halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine, and quaternary ammonium; each j, k, l, m and n, equal to or different from each other, is independently selected from 0, 1, 2, 3 and 4, preferably 0; and W is selected from the group consisting of alkylenes having 1 to 6 carbon atoms, in particular –C(CH3)2– and –CrH2r– (r being an integer ranging from 1 to 6); perfluoroalkylenes having 1 to 6 carbon atoms, in particular –C(CF3)2– and –Cs F2s–(s being an integer ranging from 1 to 6); cycloalkylenes having 4 to 8 carbon atoms; alkylidenes having 1 to 6 carbon atoms; cycloalkylidenes having 4 to 8 carbon atoms; –O– ; –S– ; –C(O)– ; –SO2– ; and –SO–.

[0091] Preferably, B is a group of the formula (B-6), as shown above. More preferably, B is a group of formula:

[0092] Each A, equal to or different from each other, is selected from the group, –CtH2t- (t being an integer ranging from 1 to 6), and moieties of formulae :where each R’, equal to or different from each other, is independently selected from the group consisting of hydrogen, halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine, and quaternary ammonium; o, p, q, v, and x, equal to or different from each other, is independently selected from 0, 1, 2, 3 and 4, preferably 0; and Y is selected from the group consisting of alkylenes having 1 to 6 carbon atoms, in particular – C(CH3)2– and –CuH2u– (u being an integer from 1 to 6); perfluoroalkylenes having 1 to 6 carbon atoms, in particular –C(CF3)2– and –CwF2w–(w being an integer from 1 to 6); cycloalkylenes having 4 to 8 carbon atoms; alkylidenes having 1 to 6 carbon atoms; cycloalkylidenes having 4 to 8 carbon atoms; –O– ; –S– ; –C(O)– ; –SO2– ; and –SO–.

[0093] Preferably, A is selected from the group consisting of moieties of formulae (C-0) to (C-2), as shown above. More preferably, A is selected from the group consisting of unsubstituted m phenylene, unsubstituted p phenylene, and a combination thereof.

[0094] In some embodiments, A is a group of formula :(C-7).

[0095] In some embodiments, the recurring units (RPEI) are recurring units selected from the group consisting of those of formulae :and combinations thereof.

[0096] In some embodiments, the recurring units (RPEI) are recurring units selected from the group consisting of those of formulae :and combinations thereof.

[0097] Preferably at least 75 mol %, 85 mol %, 95 mol %, and more preferably at least 99 mol % of the recurring units of the PEI polymer are recurring units (RPEI).

[0098] In some embodiments, at least 75 mol %, 85 mol %, 95 mol %, and more preferably at least 99 mol % of the recurring units (RPEI) are units of formula (D-0), their corresponding amic acid forms of formulae (D-1) to (D-6), and combinations thereof.

[0099] In some embodiments, at least 75 mol %, 85 mol %, 95 mol %, and more preferably at least 99 mol % of the recurring units (RPEI) are units of formula (E-0), their corresponding amic acid forms of formulae (E-1) to (E-6), and combinations thereof.

[0100] The PEI polymer may have a weight average molecular weight (Mw) ranging from about 10,000 to about 150,000 g / mole, as measured by gel permeation chromatography using a polystyrene standard.

[0101] The PEI polymer may have a glass transition temperature Tg from 220 ℃ to 250 ℃ (e.g., from 220 ℃ to 240 ℃, from 220 ℃ to 230 ℃, from 230 ℃ to 250 ℃, from 240 ℃ to 250 ℃, or from 230 ℃ to 240 ℃).

[0102] The PEI polymer is present in the polymer matrix in an amount from 1% to 50% by weight, based on the total weight of the polymer matrix (e.g., from 2% to 50%, from 3% to 50%, from 4% to 50%, from 5% to 50%, from 1% to 45%, from 1% to 40%, from 2% to 45%, from 2% to 40%, from 3% to 45%, from 3% to 40%, from 4% to 45%, from 4% to 40%, from 5% to 45%, from 5% to 40%, from 5% to 35%, from 5% to 30%, from 5% to 25%, from 5% to 20%, from 10% to 50%, from 15% to 50%, from 5% to 15%, from 10% to 20%, from 15% to 20%, or from 10% to 15%). According to this embodiment, the PAI polymer is present in the polymer matrix.

[0103] In a preferred embodiment, the PEI polymer is present in the polymer matrix in an amount lower than 10% by weight based on the total weight of the polymer matrix (e.g., from 1% to less than 10%, from 2% to less than 10%, from 3% to less than 10%, from 4% to less than 10%, and more preferably from 2% to 9% or from 3% to 9%). According to this preferred embodiment, the PAI polymer is not present in the polymer matrix.

[0104] The Polyamide-Imide (PAI) Polymer

[0105] The presently disclosed polymer matrix comprises a polyamide-imide (PAI) polymer. The PAI polymer of the present disclosure can comprise recurring units having at least 50.0 mol% of the recurring units comprising an aromatic ring and one or more of an amic acid group or an imide group [referred to as recurring units (RPAI) herein]. The PAI polymer can also comprise more than 90.0 mol% of recurring units (RPAI). The polymer solution can comprise one or more than one PAI polymer.

[0106] The acid number (mg of KOH / g polymer) of the PAI polymer) may be 100 or more and even 120 or more. It may be up to the theoretical acid number for a resin that comprises only amic acid units. In certain embodiments, it may be up to 170 mg KOH / g polymer. The acid number may be determined by titration, such as a potentiometric titration method according to ASTM D664. In particular it may be determined by the potentiometric titration method described by ASTM D664, where N-methylpyrrolidone (NMP) is the solvent, and titrants are potassium hydroxide and tributylammonium chloride.

[0107] The recurring units (RPAI) are chosen from the group consisting of:wherein the symbol → in each formula denotes isomerism so that, in any recurring unit within the aromatic polyamic acid structure, the groups to which the arrows point may exist as shown or in an interchanged position; Ar is an aromatic tetravalent group, which may comprise one or more than one aromatic ring, and which are preferably selected from the group consisting of:with X being selected from the group consisting of –O-, -C(O)-, -S-, -SO2-, -CH2-, -C(CF3)2-, - (CF2)n- with n= 0,1,2,3,4 or 5; R is an aromatic divalent group, which may comprise one or more than one aromatic ring, and which are preferably selected from the group consisting of: ,with Y being selected from the group consisting of –O-, -C(O)-, -S-, -SO2-, -CH2-, -C(CF3)2-, - (CF2)n- with n= 0,1,2,3,4 or 5,

[0108] Alternatively, or in addition, the recurring units (RPAI) are chosen from the group consisting of units (i), (ii), and (iii) as follows:and / or the corresponding imide-group containing recurring unit:wherein the attachment of the two amide groups to the aromatic ring as shown in (i-a) will be understood to represent the 1,3 and the 1,4 polyamide-amic acid configurations;and / or the corresponding imide-group containing recurring unit:(ii-b), wherein the attachment of the two amide groups to the aromatic ring as shown in (ii-a) will be understood to represent the 1,3 and the 1,4 polyamide-amic acid configurations; and(iii-a),and / or the corresponding imide-group containing recurring unit:(iii-b), wherein the attachment of the two amide groups to the aromatic ring as shown in (iii-a) will be understood to represent the 1,3 and the 1,4 polyamide-amic acid configurations.

[0109] The recurring units (RPAI) can be recurring units (i) or a mixture of the recurring units (ii) and (iii).

[0110] The amount of recurring units comprising an amic group can be determined by any suitable technique, such as spectroscopic techniques or titration techniques which are known to those of ordinary skill in the art.

[0111] When recurring units (RPAI) are selected from those of formulae (RPAI-A), (RPAI-B), (RPAI- C), (RPAI-D), (RPAI-E), as detailed above, the molar percentage of recurring units (RPAI) comprising at least one amic acid group may be expressed as follows: where [(RPAI-A) units], [(RPAI-B) units], [(RPAI-C)units], [(RPAI-D) units], and [(RPAI-E) units] denote, respectively molar concentration of the different recurring units (RPAI) as above described.

[0112] When recurring units (RPAI) are selected from those of formulae (RPAI-A), and (RPAI-C), as detailed above, the molar percentage of recurring units (RPAI) comprising at least one amic acid group may be expressed as follows: [(RPAI-A) units][(RPAI-A) units]+[(RPAI-C) units]x100.

[0113] The recurring units (RPAI) can have at least 50.0 mol%, even at least 60.0 mol%, still at least 70.0 mol% of recurring units (RPAI) comprise at least one amic acid group. Alternatively, orin addition, 70.0 to 95.0 mol%, even 75.0 to 90.0 mol% of recurring units (RPAI) comprise at least one amic acid group.

[0114] The PAI polymer can be manufactured by a process which includes the polycondensation reaction between at least an aromatic polycarboxylic acid halide monomer and at least an aromatic diamine.

[0115] The number average molecular weight (Mn) of the PAI polymer can be at least 1000, preferably at least 1500, more preferably at least 2000. The number average molecular weight (Mn) of the PAI polymer can be 20000 or less, preferably 15000 or less. The molecular weight of the PAI polymer (Mw and Mn) may be and is usually determined using gel permeation chromatography (GPC) using a polystyrene standard.

[0116] The PAI polymer is present in the polymer matrix in an amount from 0% to 5% by weight, based on the total weight of the polymer matrix (e.g., from 0.1% to 5%, from 1% to 5%, from 1% to 4%).

[0117] The embodiments above are intended to be illustrative and not limiting. Additional embodiments are within the inventive concepts. In addition, although the present invention is described with reference to particular embodiments, those skilled in the art will recognized that changes can be made in form and detail without departing from the spirit and scope of the invention.

[0118] The present invention will be now described in more detail with reference to the following examples, whose purpose is merely illustrative and not intended to limit the scope of the disclosure.

[0119] Raw Materials

[0120] The poly(phenylene sulfide) (PAS) polymer was RytonⓇM2000 SFP, which is commercially available and was obtained from Solvay Specialty Polymers USA, LLC.

[0121] The polyetherimide (PEI) polymer was UltemⓇ1000, which is commercially available and was obtained from SABIC.

[0122] The polyamide-imide (PAI) polymer was TorlonⓇAI-30, which is commercially available and was obtained from Solvay Specialty Polymers USA, LLC.

[0123] The continuous reinforcing fibers were carbon fibers, commercially available as HexTow®AS4D or Grafil®G34-700 obtained from Hexcel and Mistubishi, respectively.

[0124] Methods of Manufacture

[0125] A slurry impregnation method was used to make the thermoplastic composite. For Examples E1 and E2, blends of PAS particles, PEI particles, and PAI solution were actively mixed in an aqueous colloidal suspension according to the formulations given in Table I. For E1 and E2, unsized carbon fibers commercially available from Mitsubishi under the trade name Grafil®G34- 70012K were used. For Example CE3, PAS particles were actively mixed in an aqueous colloidal suspension, and unsized carbon fibers commercially available from Hexcel under the trade name HexTow®AS4D 12K were used. The individual fiber thickness is about 7 μm. A sufficient number of fibers were used to make a 76 mm-wide unidirectional tape. The dry web of collimated, continuous fibers were passed through the aqueous colloidal suspension of polymers along with a surfactant (Rhodasurf®Bc729, supplied by Syensqo).

[0126] After passing through the aqueous suspension, the web of collimated fibers was passed underneath a series of infrared lamps which evaporated the water and consolidated the polymers on the fibers. The fibers were then passed through a die heated to 340°C, a heated calendar maintained at 120°C, and eventually a series of cooling rolls before being coiled onto a cardboard core. The prepreg tapes have a nominal fiber volume fraction of 0.60, which results in a final polymer content of 33 wt% and a fiber areal weight of 150 g / m2.

[0127] Examples

[0128] The following Examples were prepared according to the above. The formulations prepared are given below in Table I. Table I. Example thermoplastic composite materials prepared according to the present disclosure. E1 E2 E3 CE4 PAS Polymer 96% 92% 81% 100% PEI Polymer 4% 8% 15% PAI Polymer 0% 0% 4%

[0129] Laminate Preparation and Characterization

[0130] Composite laminates were prepared on a Rucks KV 275.11 Upstroke Press equipped with 600 mm × 600 mm, a maximum platen temperature of 450°C, and a maximum press force of 1000 kN. The prepreg tape was cut and welded to proper ply dimensions according to the mold being used to press the laminates. The plies were stacked based on desired thickness and layup of thelaminate. The edges of the ply stack were taped with Kapton®to maintain fiber alignment and the dried for 2 h at 80°C in a desiccant oven. The dried ply stack was sandwiched between Kapton®sheets coated with Zyvax®Composite Shield Release and placed in a steel window frame mold for thermal pressing. The pressing procedure is displayed in Table II. Table II. Pressing procedure of composite materials given in Table I. Temperature (°C) Pressure (kPa) Dwell Time (min) Step 1 340 2413 12-15 Step 2 120 2413 15-18 Step 3 120 0 -

[0131] Samples were cut from the resulting laminates and mechanically tested according to the ASTM standards listed below in Table III. For 0° and 90° flexural tests, a three point loading system for center loading is used to test flexural properties in polymer matrix composites with a standard dimension of 4 mm in thickness and 13 mm in width. A center load is applied to induce three-point bending at a rate of 1 mm / min. For 0° short-beam shear tests, the test sample is placed on a standard fixture with the fibers parallel to the loading direction. A load is applied to induce flex at a rate of 1 mm / min. The results all of which are given in Table III.

[0132] For transverse crack observations, [0 / 90] layup of laminates were cut at a 45° bias and examined using optical microscopy. Specifically, the cut laminates were mounted and set in a two-component epoxy resin (such as Epoxicure 2™ from Buehler). After curing, the puck was progressively abraded and polished using first sandpaper then a diamond slurry on a felt pad. The sandpapers have grits of 280 / P320 to 1200 / P4000, and the series of diamond slurries (Glennel®Diamond Suspension from Electron Microscopy Sciences) have particle sizes sequentially of 3.0 μm, 1.0 μm, and eventually 0.1 μm. The polished samples were then imaged using an optical microscope under magnification levels of 100-300x to look for transverse cracks. The results of which are given in Table III.Table III. Transverse crack and mechanical measurements of composite materials given in Table I. 0° flexural 90° flexural 0° Short-beam Transverse strength (MPa) strength (MPa) shear strength cracks (MPa) Standards ASTM D7264 ASTM D7264 ASTM D2344 E1 1660 ± 86 127 ± 14 98 ± 1 N E2 1692 ± 67 126 ± 6 94 ± 2 N E3 1740 ± 80 91 ± 7 98 ± 1 N CE4 1562 ± 127 76 ± 4 76 ± 2 Y

[0133] H2Permeation Coefficient Determination

[0134] Additional tests were performed to measure the hydrogen permeation of the thermoplastic composite material. The results are given below in Table IV.

[0135] Samples for hydrogen permeation testing were prepared have been prepared following the press consolidation conditions described above. Lay up: [0,+45,90,-45]2s. Samples of 90 x 90 mm were cut and mounted on a cell so as to form a barrier between two chambers. An epoxy glue was put around the sheets to minimize side permeation. The cell was conditioned at 55 °C to determine H2 permeation according to the H2 tank standard R 134. One chamber contains the test gas (H2) and the other chamber is purged with a sweep gas (synthetic air). The feed side is pressurised with H2 and during the measurement, the concentration of H2 in the sweep gas flow is measured, typically with an electrochemical H2 sensor. Permeation coefficient (P) is calculated according to the equationP = (C·D·d / A·pp).(T°·p / T·p°) wherein: P = permeation coefficient (Ncm3·mm / m2·day·bar) C = penetrant concentration (ppm) D = sweep gas flow rate (mL / min) d = sample thickness (mm) A = testing area in contact with the gas (m2) pp = penetrant partial pressure (bar) T = ambient temperature (K) p = ambient pressure (bar) T° = standard temperature (273.15 K) p° = standard pressure (1.013 bar).

[0136] Further normalization is done to standard temperature and pressure, i.e.273.15 K and 1.013 bar.

[0137] Plate samples were tested under the following conditions: - Condition 0: as such, no thermal treatment (@ 55°C); - Condition 1: after 5 thermal cycles as follows 30 minutes at - 65 °C and 30 minutes at 100 °C; - Condition 2: after 5 thermal cycles as in Condition 1 followed by 5 cycles in liquid nitrogen (30 minutes in liquid nitrogen and 30 minutes at room temperature).

[0138] The results (hydrogen permeation coefficient at 55 °C), N.cm3(STP).mm / m2.d.b are shown in Table 4. Table IV. Hydrogen permeation of thermoplastic composite materials after five thermal cycles given in Table I. Condition 0 (cm3(STP) Condition 1 (cm3(STP) Condition 2 (cm3(STP) mm / m2d bar) mm / m2d bar) mm / m2d bar) E1 n / a 15.2 15.0 E2 14.4 21.1 E3 21.8 21.3CE4 13.6 33.6 n / a

[0139] As can be seen, the binary blend composite materials in E1 and E2 and the ternary blend composite material E3 all present improved 90° flexural strength and 0° short-beam shear strength compared to CE4, which consists of 100% PAS polymer in the matrix.

[0140] Accordingly, the Applicant found that composite materials which include the presently disclosed ternary blend of polymers in the polymer matrix did eliminate the formation of microcracks in composite materials while also showing improved tensile properties.

[0141] The inventive materials show markedly lower hydrogen gas permeation after thermal cycling when made into laminates, making them great candidates for pressurized hydrogen tanks, i.e. tanks type 4 (with a PPS liner) and even tanks type 5 (full composite, no liner). Furthermore liquid H2 and cryogenic compressed hydrogen tanks can be considered taking into account limited / no transverse cracking even after thermal cycling.

Claims

CLAIMS What is claimed is:

1. A multilayer structure comprising a thermoplastic composite material, the thermoplastic composite material comprising continuous reinforcing fibers and a polymer matrix, wherein the polymer matrix comprises: a poly(arylene sulfide) (PAS) polymer; a polyetherimide (PEI) polymer in an amount from 1% to lower than 10% by weight based on the total weight of the polymer matrix.

2. A multilayer structure comprising a thermoplastic composite material, the thermoplastic composite material comprising continuous reinforcing fibers and a polymer matrix, wherein the polymer matrix comprises: a poly(arylene sulfide) (PAS) polymer; a polyetherimide (PEI) polymer in an amount from 1.0% to 50% by weight, based on the total weight of the polymer matrix; and a polyamide-imide (PAI) polymer in an amount from 0.1% to 5.0% by weight, based on the total weight of the polymer matrix.

3. The multilayer structure of Claim 1 or Claim 2, wherein the PAS polymer is polyphenylene sulfide.

4. The multilayer structure of any of Claims 2 or 3, wherein the PAI polymer comprises recurring units having at least 50.0 mol% of the recurring units comprising (i) an aromatic ring and (ii) one or more of an amic acid group or an imide group [recurring units (RPAI)].

5. The multilayer structure of any of Claims 2 to 4, wherein the PAI polymer is present in an amount from 0.1% to 5.0% by weight, based on the total weight of the polymer matrix.

6. The multilayer structure of any of Claims 1–5, wherein the PEI polymer has a glass transition temperature Tg from 220 ℃ to 250 ℃.

7. The multilayer structure of any of Claims 1–6, wherein the continuous reinforcing fibers are selected from the group consisting of glass fibers, carbon fibers, aramid fibers, ceramic fibers, and mixture thereof.

8. The multilayer structure of any of Claims 1–7, wherein the volume of the continuous reinforcing fibers is from 45% to 65% with respect to the total volume of the multilayer structure.

9. An article for storing or transporting a gas comprising at least one layer made of the multilayer structure of any of Claims 1–8.

10. The article of Claim 9, wherein the article is in the form of a vessel or a hose.

11. A vessel comprising the multilayer structure of any of Claims 1–8.

12. The vessel of Claim 11, wherein the vessel is in the shape of a hollow body defined by one or more of the following: a diameter of 10.0 cm to 1.0 m; a length of 50.0 cm to 10.0 m; and an internal volume of 3.5 dm3to 5.0 m3.

13. A compressed gas, a liquid, or a cryo compressed gas contained in the vessel of Claim 12.

14. The compressed gas of Claim 13, wherein the compressed gas is selected from the group consisting of hydrogen, oxygen, nitrogen, argon, helium, methane, propane, compressed natural gas, CO2, and ammonia.

15. A vehicle comprising the vessel of Claim 12 or the compressed gas of any of Claims 13–14.

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