Composition of polyamide and polar graphene

Abstract

The invention relates to a composition comprising, relative to the total weight of the composition: at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2; from 0.05 to 20% by weight of a polar graphene; and from 3 to 40% by weight of at least one shock modifier. The invention also relates to the use of this composition for the preparation of single-layer or multi-layer structures for the storage, transport, and distribution of fluids, particularly transport vehicle fluids. Figure: None

Description

Title of the invention: Polyamide and polar graphene composition Scope of the invention

[0001] The present invention relates to polyamide and graphene compositions for the manufacture of single-layer or multi-layer structures, in particular for applications in the transport, distribution or storage of fluids. Technical background

[0002] The supply of fluid to transport vehicles, for example motor vehicle, train, truck, etc., in particular the supply of fuel for thermal vehicles, the supply of cooling fluid, the supply of hydrogen to fuel cells, etc., requires the presence of storage, distribution and transport structures of the type tank, pipe, etc.

[0003] These structures must fulfill two essential functions: Sealing or low permeability to limit fluid losses; Mechanical resistance (in tension and impact).

[0004] Furthermore, it is essential that the fluid carries little or no contaminants from the storage, distribution, or transport structures. Therefore, it is essential that the compositions forming said storage, distribution, or transport structures have the lowest possible extractable content.

[0005] There is therefore a real need to provide compositions enabling the preparation of structures for the storage, distribution and / or transport of fluids, in particular fluids used in transport vehicles, which, in addition to good mechanical strength properties: Low permeability to limit fluid losses; and / or a low extractable rate.

[0006] There is also a need to provide such compositions for preparing fluid storage, distribution and / or transport structures that also have: Good fire resistance, in particular the structure is fire-resistant with a V0, VI or V2 result on the UL94 test (IEC 60695-11-10); and / or Good thermal and / or electrical conductivity; and / or A good compromise between low density and good mechanical strength. Summary of the invention

[0007] The invention relates primarily to a composition comprising, relative to the total weight of the composition: - At least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2; - From 0.05 to 20% by weight of a polar graphene; - From 3 to 40% by weight of at least one shock modifier.

[0008] In one embodiment, polar graphene is a graphene oxide or graphene functionalized with at least one function reacting with the polyamide, preferably a function selected from maleic anhydrides, carboxylic acids, primary amines, isocyanates, preferably maleic anhydrides and amines.

[0009] In one embodiment, the polar graphene has a number of oxygen atoms between 50 and 99.9% relative to the total number of atoms in the graphene, excluding any hydrogen atoms present in the graphene.

[0010] In one embodiment, the polyamide of the composition according to the invention is: - An aliphatic polyamide obtained by polycondensation: • of at least one amino acid in the C6 to C8 range, preferably in the C9 to C8 range, more preferably in the C10 to C18 range, and even more preferably in the C10 to C12 range, particularly in the C1 range; or • of at least one lactam at C6 to C18, preferentially at C9 to C18, more preferentially at C10 to C18, and even more preferentially at C10 to C12, particularly at C12; or • of at least one aliphatic diamine Ca in the C4-C36 position, particularly in the C6-C36 position, preferentially in the C6-C18 position, preferentially in the C6-C12 position, more preferentially in the C10-C12 position, with at least one aliphatic diacid Cb in the C4-C36 position, particularly in the C6-C36 position, preferentially in the C6-C18 position, preferentially in the C10-C18 position, more preferentially in the C10-C12 position; or - A semi-aromatic polyamide of formula A / XT in which A is selected from a motif obtained from an amino acid, a motif obtained from a lactam and a motif corresponding to the formula (diamine in Ce).(diacid in Cd), with c representing the number of carbon atoms of the diamine and d representing the number of carbon atoms of the diacid, c and d each being between 4 and 36, advantageously between 9 and 18, the motif (diamine in Ce) being selected from the aliphatic diamines, linear or branched, as defined above, the cycloaliphatic diamines and the alkylaromatic diamines and the motif (diacid in Cd) being selected from the aliphatic diacids, linear or branched, the cycloaliphatic diacids and the aromatic diacids; XT denotes a motif obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 5 and 36, before Tageously between 9 and 18, T corresponds to terephthalic acid.

[0011] Preferably, the polyamide is: - An aliphatic polyamide selected from PA6, PA66, PAU, PA12, PA610, PA612, PA1010, PA1012 and PA1212; - A semi-aromatic polyamide chosen from a PA MPMDT / 6T, a PA11 / 10T, a PA 5T / 10T, a PA 11 / BACT, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, PA BACT / 10T / 6T, a PA 11 / BACT / 6T, PA 11 / MPMDT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, a PA 11 / MXDT / 10T, an 11 / 5T / 10T, T corresponds to terephthalic acid, MXD corresponds to m-xylylene diamine, MPMD corresponds to methylpentamethylene diamine and BAC corresponds to bis(aminomethyl)cyclohexane.

[0012] In one embodiment, the shock modifier is chosen from olefin copolymers and in particular copolymers comprising ethylene or propylene motifs.

[0013] The present invention also relates to single-layer or multi-layer structures in which the layer in the case of the single-layer structure or at least one of the layers in the case of the multi-layer structure is formed in whole or in part from the composition according to the invention.

[0014] In one embodiment, these structures are tubular structures.

[0015] In another embodiment, these structures are reservoirs.

[0016] The present invention also relates to the use of said structures for the transport, distribution and storage of a fluid.

[0017] In one embodiment, the fluid is hydrogen.

[0018] In another embodiment, the fluid is a fuel.

[0019] The present invention also relates to the use of a composition according to the invention for the manufacture of a single-layer or multi-layer structure by injection, extrusion, extrusion-blowing or rotomolding, preferably by extrusion.

[0020] The present invention also relates to the use of 0.05 to 20% by weight of at least one polar graphene in a composition comprising at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, optionally up to 5% by weight of at least one additive, optionally up to 40% by weight of at least one shock modifier and / or optionally up to 14% by weight of at least one plasticizer, the percentages being given in relation to the total weight of the composition, to obtain an extractable rate less than or equal to 4g / m2, preferably less than or equal to 3g / m2.

[0021] The present invention also relates to the use of 0.05 to 20% by weight of at least one polar graphene in a composition comprising at least 50% in weight of at least one polyamide having an inherent viscosity greater than 1.2, possibly up to 5% by weight of at least one additive, possibly up to 40% by weight of at least one shock modifier and / or possibly up to 14% by weight of at least one plasticizer, the percentages being given in relation to the total weight of the composition, to obtain an extractable rate lower than that obtained for the same composition free of graphene in which the graphene has been replaced by the same quantity of polyamide.

[0022] The present invention also relates to the use of 0.05 to 20% by weight of at least one polar graphene, in a composition comprising at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, optionally up to 5% by weight of at least one additive, optionally up to 40% by weight of at least one shock modifier and / or optionally up to 14% by weight of at least one plasticizer, the percentages being given in relation to the total weight of the composition, to obtain a permeability lower than that obtained for the same composition free of graphene in which the graphene has been replaced by the same quantity of polyamide.

[0023] The present invention also relates to a method of manufacturing a single-layer or multi-layer structure, characterized in that it includes a step of manufacturing a sealing layer by injection, extrusion, extrusion blow molding or rotomolding.

[0024] In a particularly advantageous way, the inventors have shown that the combination of polyamide with graphene makes it possible to improve in particular the mechanical resistance while limiting the density of the storage, distribution and / or transport structures of fluid prepared from these compositions. Detailed description

[0025] The invention is now described in more detail and in a non-limiting manner in the following description.

[0026] Unless otherwise indicated, all percentages are mass percentages.

[0027] In this text, the quantities indicated for a given species may apply to that species according to all its definitions (as mentioned in this text), including more restricted definitions. Composition Polyamide

[0028] The composition according to the invention comprises at least 50% by weight, preferably from 70 to 99.5% by weight, more preferably from 90 to 99% by weight, of at least one polyamide.

[0029] The nomenclature used to define polyamides is described in the ISO standard 1874-1:2011 "Plastics - Polyamide (PA) materials for molding and extrusion - Part 1: Designation", especially on page 3 (tables 1 and 2) and is well known to those skilled in the art.

[0030] The polyamide has an inherent viscosity greater than 1.2, preferably greater than 1.3, more preferably greater than 1.4, even more preferably greater than 1.6.

[0031] The measurement of inherent (or intrinsic) viscosity is carried out in m-cresol. The method is well known to those skilled in the art. ISO 307:2007 is followed, but with a change in solvent (using m-cresol instead of sulfuric acid), temperature (20°C), and concentration (0.5% by mass).

[0032] The polyamide of the invention is advantageously a polyamide compatible with use in injection or extrusion, preferably in extrusion.

[0033] The polyamide can be a homopolyamide or a copolyamide or a mixture of these.

[0034] Polyamide is a semi-crystalline polyamide, that is to say a material which is generally solid at room temperature, and which softens when the temperature increases, in particular after passing its glass transition temperature (Tg), and which may exhibit a clear melting when passing its so-called melting temperature (Tf), and which becomes solid again when the temperature decreases below its crystallization temperature.

[0035] Tg, Te (crystallization temperature) and Tf are determined by differential scanning calorimetry (DSC) according to standard 11357-2:2013 and 11357-3:2013 respectively.

[0036] The number-average molecular weight Mn of said semi-crystalline polyamide is preferably in the range of 10,000 to 85,000 g / mol, in particular 10,000 to 60,000 g / mol, preferably 10,000 to 50,000 g / mol, and even more preferably 12,000 to 50,000 g / mol. The number-average molecular weight Mn can be measured by any method known to those skilled in the art, and in particular the number-average molecular weight (Mn) and weight-average molecular weight (Mw) is determined by size-exclusion chromatography according to ISO 16014-1:2012, 16014-2:2012 and 16014-3:2012 using the following conditions:

[0037] Device: Waters Alliance 2695 instrument

[0038] Solvent: hexafluoroisopropanol stabilized with 0.05M potassium trifluoroacetate

[0039] Flow rate: 1 ml / minute

[0040] Column temperature: 40°C.

[0041] Two columns in series: 1000 Â PFG and 100 Â PFG (PPS)

[0042] Sample concentration: 1 g / L (dissolution at room temperature for 24 h)

[0043] Filtration of samples using a syringe fitted with an ACRODISC PTFE filter, 25mm diameter, 0.2 pm porosity

[0044] Injection volume: lOOpl

[0045] Refractometric detection at 40°C with UV detection at 228 nm

[0046] Calibration by PMMA standards from 1,900,000 to 402 g.mol-1. Calibration curve modeled by a fifth degree polynomial.

[0047] In one embodiment, the polyamide is chosen from an aliphatic polyamide, a semi-aromatic polyamide and a mixture of the two, advantageously an aliphatic polyamide.

[0048] Said aliphatic polyamide can be obtained from polycondensation:

[0049] of at least one amino acid in the C6 to C8 range, preferably in the C9 to C8 range, more preferably in the C10 to C18 range, even more preferably in the C10 to C12 range, particularly in C11; or

[0050] of at least one lactam at C6 to C18, preferably at C9 to C18, more preferably at C10 to C18, even more preferably at C10 to C12, especially at C12; or

[0051] of at least one aliphatic diamine Ca in C4-C36, in particular in C6-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12 with at least one aliphatic diacid Cb in C4-C36, in particular in C6-C36, preferably C6-C18, preferably C10-C18, more preferably C10-C12.

[0052] An amino acid in C6 to C12 is in particular 6-aminohexanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, 10-aminoundecanoic acid, 12-aminododecanoic acid and 11-aminoundecanoic acid and its derivatives, in particular N-heptyl-11-aminoundecanoic acid.

[0053] When said at least one aliphatic semi-crystalline polyamide is obtained from the polycondensation of at least one amino acid, it may therefore comprise a single amino acid or several amino acids.

[0054] Advantageously, said aliphatic semi-crystalline polyamide is obtained from the polycondensation of a single amino acid and said amino acid is chosen from 11-aminoundecanoic acid and 12-aminododecanoic acid, advantageously 11-aminoundecanoic acid.

[0055] The lactam in C6 to C12 is in particular caprolactam, decanolactam, undecanolactam, and lauryllactam.

[0056] When said at least one aliphatic semi-crystalline polyamide is obtained from the polycondensation of at least one lactam, it may therefore comprise a single lactam or several lactams.

[0057] Advantageously, said at least one aliphatic semi-crystalline polyamide is obtained from the polycondensation of a single lactam and said lactam is selected from the lauryllactam and undecanolactam, advantageously lauryllactam.

[0058] The diamine in Ca can be linear or branched. Advantageously, it is linear.

[0059] Said at least one diamine Ca in C4-C36 may in particular be chosen from the butanemethylenediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine, 1,13-tridecamethylenediamine, 1,14-tetradecamethylenediamine, 1,16-hexadecamethylenediamine and 1,18-octadecamethylenediamine, octadecenediamine, eicosanediamine, docosanediamine and diamines obtained from fatty acids.

[0060] Advantageously, said at least one diamine Ca is in C6-C36 and selected from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 2,2,4-trimethylhexanediamine (TMD), 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine, 1,13-tridecamethylenediamine, 1,14-tetradecamethylenediamine, 1,16-hexadecamethylenediamine and 1,18-octadecamethylenediamine, octadecenediamine, eicosanediamine, docosanediamine and diamines obtained from fatty acids.

[0061] Said at least one Cb dicarboxylic acid in C4 to C36 may be selected from butanedioic acid, pentanedioic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid, and diacids obtained from fatty acids.

[0062] The diacid can be linear or branched. Advantageously, it is linear.

[0063] Preferably, the polyamide according to the invention has a C / N ratio greater than 6.5, preferably greater than 8, advantageously greater than 9.

[0064] Advantageously, the aliphatic polyamide is selected from PA6, PA66, PAU, PA12, PA610, PA612, PA1010, PA1012 and PA1212, preferably PAU, PA12, PA610, PA612, PA1010, PA1012 and PA1212, preferably PAU, PA610, PA1010, PA1012 and PA1212, preferably PA11 and PA12, preferably PAU.

[0065] Said semi-aromatic polyamide may be, in particular, a semi-aromatic polyamide of formula X / YAr, as described in EPI505099, in particular a semi-aromatic polyamide of formula A / XT in which A is selected from a motif obtained from an amino acid as defined above, a motif obtained from of a lactam as defined above and a motif corresponding to the formula (diamine in Ce).(diacid in Cd), with c representing the number of carbon atoms of the diamine and d representing the number of carbon atoms of the diacid, c and d each being between 4 and 36, advantageously between 9 and 18, the motif (diamine in Ce) being chosen from the aliphatic diamines, linear or branched, as defined above, the cycloaliphatic diamines and the alkylaromatic diamines and the motif (diacid in Cd) being chosen from the aliphatic diacids, linear or branched, as defined above, the cycloaliphatic diacids and the aromatic diacids;

[0066] XT designates a motif obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 5 and 36, advantageously between 9 and 18, in particular a polyamide of formula A / 5T, A / 6T, A / 9T, A / 10T or A / 1T, A being as defined above, in particular a polyamide selected from PA MPMDT / 6T, PA11 / 10T, PA 5T / 10T, PA 11 / BACT, PA 11 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T, PA BACT / 10T / 6T, PA 11 / BACT / 6T, PA 11 / MPMDT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, one PA 11 / MXDT / 10T, one 11 / 5T / 10T.

[0067] T corresponds to terephthalic acid, MXD corresponds to m-xylylene diamine, MPMD corresponds to methylpentamethylene diamine and BAC corresponds to bis(aminomethyl)cyclohexane.

[0068] Said semi-aromatic polyamide can also be a polyamide of formula ZAr in which Z is a motif resulting from the polycondensation of at least one aliphatic diamine in Ca as defined above and Ar is an aromatic dicarboxylic acid, in particular terephthalic acid, isophthalic acid and na-phthalenic acid.

[0069] In one embodiment, the polyamide is aliphatic and selected from PA6, PA66, PAU, PA12, PA610, PA612, PA1010, PA1012 and PA1212.

[0070] In another embodiment, the polyamide is semi-aromatic and selected from polyamide 11 / 5T, 11 / 6T, 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T.

[0071] In one embodiment, said polyamide of said composition is pre-washed at least once with a system selected from a polar solvent, in particular methanol, water or steam, or a mixture thereof. Polar graphene

[0072] The composition of the invention comprises from 0.05 to 20% by weight, preferably from 0.1 to 15% by weight, more preferably from 0.1 to 5% by weight, even more preferably from 0.1 to 2% by weight of at least one polar graphene.

[0073] In the case of an analysis of the graphene included in the composition, the characteristic The physicochemical determination of graphene is carried out after calcination of the graphene for 12 minutes at 600°C in a closed crucible placed in a muffle furnace, or after dissolution of the matrix and filtration of the graphene. Dissolution is preferably carried out in meta-cresol or hexafluoroispropanol at 25°C.

[0074] The specific surface area is measured according to the BET method as described in ISO 9277:2010.

[0075] The term "polar graphene" means graphene not composed solely of carbon atoms, that is to say, graphene comprising carbon atoms and other atoms such as, for example, heteroatoms, for example O, N, F, etc.

[0076] Preferably, the polar graphene comprises oxygen atoms. Preferably, the polar graphene according to the invention has a carbon atom content, relative to the total number of atoms of the graphene (excluding any hydrogen atoms present in the graphene), less than or equal to 99.9%, preferably between 55 and 99.5%, advantageously between 65 and 98%, more preferably between 75 and 95%.

[0077] Preferably, the polar graphene according to the invention has a number of oxygen atoms relative to the total number of graphene atoms (excluding any hydrogen atoms present in the graphene) of between 0.1 and 45%, preferably between 5 and 35%.

[0078] The determination of the ratios between the different atoms present in graphene can be carried out by elemental analysis. This method is described in the scientific article “Jianguo Song, Xinzhi Wang, Chang-Tang Chang, "Preparation and Characterization of Graphene Oxide", Journal of Nanomaterials, vol. 2014, Article ID 276143, 6 pages, 2014”.

[0079] The specific surface area according to the BET method is between 20 and 1000 m2 / g, preferably between 50 and 750 m2 / g.

[0080] Polar graphene may in particular be an oxidized graphene (graphene oxide in English) or a graphene comprising at least one function reacting with the polyamide, in particular at least one function selected from maleic anhydrides, carboxylic acids, primary amines, isocyanates, preferably maleic anhydrides and amines.

[0081] Polar graphene preferably has an average thickness of between 1 and 100 nm, preferably between 1.5 and 50 nm, more preferably between 2 and 25 nm.

[0082] Polar graphene has lateral dimensions between 0.4 and 50 pm, preferably between 2 and 40 pm.

[0083] The number of graphene layers can be determined using X-ray diffraction or atomic force microscopy. Raman spectroscopy is preferred for graphene materials with few layers. The thickness and dimensions The thickness and lateral dimensions of graphene can also be determined using optical, scanning electron, or transmission electron microscopy. Methods for measuring the average thickness and lateral dimensions of graphene are described in ISO / TS 21356-1:2021.

[0084] Advantageously, graphene and polyamide are covalently linked by an amide, ester, urea or urethane function, preferably amide. Shock modifier

[0085] The shock modifier may be present up to 40% by weight relative to the total weight of the composition.

[0086] In one embodiment, the shock modifier is present up to 35% by weight relative to the total weight of the composition, in particular up to 30% by weight relative to the total weight of the composition, preferably up to 15% by weight, preferably up to 12% by weight relative to the total weight of the composition.

[0087] In another embodiment, the shock modifier is present from 3 to 40% by weight relative to the total weight of the composition, in particular from 3 to 35%, especially from 3 to 30% by weight, preferably from 3 to 15% by weight, for example from 3 to 12% by weight, relative to the total weight of the composition.

[0088] The shock modifier is advantageously made up of a polymer having a flexural modulus of less than 100 MPa measured according to ISO 178:2010, determined at 23°C with a relative humidity of RH50%, and of Tg less than 0°C (measured according to standard 11357-2:2013 at the inflection point of the DSC thermogram, at a heating rate of 20K / min), in particular a polyolefin.

[0089] In one embodiment, polyether block amides (PEBA) are excluded from the definition of shock modifiers.

[0090] The shock modifier polyolefin may be functionalized or non-functionalized, or a mixture of at least one functionalized and / or at least one non-functionalized polyolefin. For simplicity, the polyolefin has been designated by (B), and functionalized polyolefins (B1) and non-functionalized polyolefins (B2) are described below.

[0091] A non-functionalized polyolefin (B2) is classically a homopolymer or copolymer of alpha olefins or diolefins, such as, for example, ethylene, propylene, 1-butene, 1-octene, butadiene. Examples include:

[0092] - polyethylene homopolymers and copolymers, in particular LDPE, HDPE, LLDPE (linear low density polyethylene), VLDPE (very low density polyethylene) and metallocene polyethylene.

[0093] - homopolymers or copolymers of propylene.

[0094] - ethylene / alpha-olefin copolymers such as ethylene / propylene, the EPR (abbreviation for ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM).

[0095] - styrene / ethylene-butene / styrene block copolymers (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS).

[0096] - copolymers of ethylene with at least one product selected from the salts or the esters of unsaturated carboxylic acids such as alkyl (meth)acrylate (e.g. methyl acrylate), or vinyl esters of saturated carboxylic acids such as vinyl acetate (EVA), the proportion of comonomer can reach 40% by weight.

[0097] The functionalized polyolefin (B1) can be a polymer of alpha olefins having reactive motifs (the functionalities); such reactive motifs are acid, anhydride, or epoxy functions. By way of example, one can cite the preceding polyolefins (B2) grafted or co- or ter-polymerized with unsaturated epoxides such as glycidyl (meth)acrylate, or with carboxylic acids or the corresponding salts or esters such as (meth)acrylic acid (the latter being able to be totally or partially neutralized by metals such as Zn, etc.) or even with anhydrides of carboxylic acids such as maleic anhydride. A functionalized polyolefin is for example a PE / EPR mixture, the weight ratio of which can vary widely, for example between 40 / 60 and 90 / 10, said mixture being co-grafted with an anhydride, in particular maleic anhydride, according to a grafting rate for example of 0.01 to 5% by weight.

[0098] The functionalized polyolefin (Bl) can be selected from the following (co)polymers, grafted with maleic anhydride or glycidyl methacrylate, in which the grafting ratio is, for example, from 0.01 to 5% by weight:

[0099] - PE, PP, copolymers of ethylene with propylene, butene, hexene, or octene containing, for example, 35 to 80% by weight of ethylene;

[0100] - ethylene / alpha-olefin copolymers such as ethylene / propylene, EPR (abbreviation for ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM).

[0101] - styrene / ethylene-butene / styrene block copolymers (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS).

[0102] - ethylene and vinyl acetate (EVA) copolymers, containing up to 40% in weight of vinyl acetate;

[0103] - ethylene and alkyl (meth)acrylate copolymers, containing up to 40% in weight of alkyl (meth)acrylate;

[0104] - ethylene and vinyl acetate (EVA) and alkyl (meth)acrylate copolymers, containing up to 40% by weight of comonomers.

[0105] The functionalized polyolefin (Bl) can also be selected from ethylene / propylene copolymers major in propylene grafted with maleic anhydride and then condensed with mono-amino polyamide (or polyamide oligomer) (products described in EP-A-0342066).

[0106] The functionalized polyolefin (Bl) may also be a co- or ter-polymer of at least the following motifs: (1) ethylene, (2) alkyl (meth)acrylate or saturated carboxylic acid vinyl ester and (3) anhydride such as maleic anhydride or (meth)acrylic acid or epoxy such as glycidyl (meth)acrylate.

[0107] By way of example of functionalized polyolefins of this latter type, the following copolymers may be cited, where ethylene preferably represents at least 60% by weight and where the ter-monomer (the function) represents, for example, from 0.1 to 10% by weight of the copolymer:

[0108] - ethylene / alkyl (meth)acrylate / (meth)acrylic acid copolymers or maleic anhydride or glycidyl methacrylate;

[0109] - ethylene / vinyl acetate / maleic anhydride or methacrylate copolymers glycidyl;

[0110] - ethylene / vinyl acetate or alkyl (meth)acrylate / acid copolymers (meth)acrylic or maleic anhydride or glycidyl methacrylate.

[0111] In the preceding copolymers, (meth)acrylic acid can be salified with Zn or Li.

[0112] The term "alkyl (meth)acrylate" in (B 1) or (B2) refers to Cl to C8 alkyl methacrylates and acrylates, and may be selected from methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, ethyl-2-hexyl acrylate, cyclohexyl acrylate, methyl methacrylate and ethyl methacrylate.

[0113] Furthermore, the aforementioned polyolefins (B 1) can also be crosslinked by any suitable process or agent (diepoxy, diacid, peroxide, etc.); the term functionalized polyolefin also includes mixtures of the aforementioned polyolefins with a difunctional reagent such as a diacid, dianhydride, diepoxy, etc. capable of reacting with them or mixtures of at least two functionalized polyolefins capable of reacting with each other.

[0114] The copolymers mentioned above, (B 1) and (B2), can be copolymerized statistically or sequentially and exhibit a linear or branched structure.

[0115] The molecular weight, MFI, and density of these polyolefins can also vary considerably, a fact that those skilled in the art will appreciate. MFI, short for Melt Flow Index, is the melt flow index. It is measured according to ASTM 1238.

[0116] Advantageously, the non-functionalized polyolefins (B2) are selected from homopolymers or copolymers of polypropylene and any homopolymer of ethylene or copolymer of ethylene and a higher alpha-olefin comonomer such as butene, hexene, octene, or 4-methyl-1-pentene. Examples include Examples include PP, high-density PE, medium-density PE, linear low-density PE, low-density PE, and ultra-low-density PE. These polyethylenes are known to those skilled in the art as being produced using a "radical" process, a "Ziegler" type catalysis, or, more recently, a so-called "metallocene" catalysis.

[0117] Advantageously, functionalized polyolefins (Bl) are selected from all polymers comprising alpha olefin motifs and motifs bearing polar reactive functions such as epoxy, carboxylic acid, or carboxylic acid anhydride groups. Examples of such polymers include terpolymers of ethylene, alkyl acrylate, and maleic anhydride or glycidyl methacrylate, such as Lotader® (SK Functional polymer), or polyolefins grafted with maleic anhydride, such as Orevac® (SK Functional polymer), as well as terpolymers of ethylene, alkyl acrylate, and (meth)acrylic acid. Also included are homopolymers or copolymers of polypropylene grafted with a carboxylic acid anhydride and then condensed with polyamides or monoamine oligomers of polyamide.

[0118] Preferably, the shock modifier of the invention, which is preferably a polyolefin as described above, has a carbon atomic content greater than 70%, preferably greater than 80%, and more preferably greater than 90%, relative to the number of atoms in the polyolefin excluding hydrogen atoms. This carbon content makes it possible to determine a certain polarity of the shock modifier. The carbon content of the shock modifier can be measured by any technique known to those skilled in the art, and in particular by elemental analysis.

[0119] Preferably, the shock modifier is chosen from olefin copolymers and in particular copolymers comprising ethylene or propylene motifs. Additive

[0120] The composition according to the invention may further comprise at least one additive. The additive may be present at up to 5% by weight relative to the total weight of the composition. Thus, the composition according to the invention comprises from 0 to 5% by weight of additive relative to the total weight of the composition.

[0121] In one embodiment, the additive is present from 0.1 to 5% by weight relative to the total weight of the layer composition (I).

[0122] The additives can be selected from an antioxidant, a polycondensation catalyst, a heat stabilizer, a UV absorber, a light stabilizer, a lubricant, an inorganic filler, a flame retardant, a nucleating agent, a plasticizer, a colorant, carbon black and carbon nanofillers.

[0123] In the context of the present invention, “polycondensation catalyst” means the catalysts used for the preparation of polyamide.

[0124] Preferably, the composition of the invention includes as an additive at least one organic or inorganic stabilizer such as phenolic antioxidants, phosphite or comprising copper.

[0125] In one embodiment, the composition of the invention may further comprise from 5 to 49% by weight, preferably from 5 to 30% by weight, relative to the total weight of the composition, of short reinforcing fibers.

[0126] the so-called short fibers are of length between 100 and 400 pm, preferably between 200 and 400 pm.

[0127] These short reinforcing fibers can be selected from: - natural fibers - mineral fibres, these having high melting temperatures Tf and higher than the melting temperature Tf of said semi-crystalline polyamide of the invention and higher than the polymerisation and / or processing temperature. - polymeric or polymer fibers having a melting temperature Tf' or failing Tf', a glass transition temperature Tg', higher than the polymerization temperature or higher than the melting temperature Tf of said semi-crystalline polyamide constituting said matrix of the thermoplastic material and higher than the processing temperature. - or mixtures of the fibers mentioned above.

[0128] Suitable mineral fibers for the invention include carbon fibers, including carbon nanotube or carbon nanotube (CNT) fibers, carbon nanofibers or graphene; silica fibers such as glass fibers, especially of type E, R or S2; boron fibers; ceramic fibers, especially silicon carbide fibers, boron carbide fibers, boron carbonitride fibers, silicon nitride fibers, boron nitride fibers, basalt fibers; fibers or filaments based on metals and / or their alloys; metal oxide fibers, especially alumina (Al2O3); metallized fibers such as metallized glass fibers and metallized carbon fibers or mixtures of the aforementioned fibers.

[0129] More specifically, these fibres can be selected as follows: - Mineral fibers can be chosen from: carbon fibers, carbon nanotube fibers, glass fibers, particularly type E, R or S2, boron fibers, ceramic fibers, particularly silicon carbide fibers, boron carbide fibers, boron carbonitride fibers, silicon nitride fibers, boron nitride fibers, basalt fibers, fibers or filaments based on metals and / or their alloys, fibers based on metal oxides such as Al2O3, metallized fibers such as glass fibers

[0130]

[0131]

[0132]

[0133]

[0134] metallized and metallized carbon fibers or blends of the aforementioned fibers, and - polymer or polymeric fibers, under the aforementioned condition, are chosen from: - thermosetting polymer fibers, and more particularly selected from: unsaturated polyesters, epoxy resins, vinyl esters, phenolic resins, polyurethanes, cyanoacrylates and polyimides, such as bis-maleimide resins, aminoplasts resulting from the reaction of an amine such as melamine with an aldehyde such as glyoxal or formaldehyde, - thermoplastic polymer fibers, and more specifically selected from: - polyamide fibers, in particular polyphthalamide fibers, - aramid fibers (such as Kevlar®) and aromatic polyamides such as those corresponding to one of the formulas: PPD.T, MPD.I, PAA and PPA, with PPD and MPD being respectively p- and m-phenylenediamine, PAA being polyarylamides and PPA being polyphthalamides, - polyamide block copolymer fibers such as polyamide / polyether, polyarylether ketone (PAEK) fibers such as polyetherether ketone (PEEK), polyetherketone ketone (PEKK), polyetherketone-etherketone ketone (PEKEKK). Preferred short reinforcing fibers are short fibers selected from: carbon fibers, including metallized, glass fibers, including metallized type E, R, S2, aramid fibers (such as Kevlar®) or aromatic polyamides, polyarylether ketone (PAEK) fibers, such as polyetherether ketone (PEEK), polyetherketone ketone (PEKK) fibers, polyetherketoneetherketone ketone (PEKEKK) fibers or mixtures thereof. Natural fibers can be chosen from flax, castor, wood, sisal, kenaf, coconut, hemp and jute fibers. Preferably, the reinforcing fibers present in the composition according to the invention are chosen from glass fibers, carbon fibers, flax fibers and their mixtures, and more preferably glass fibers and carbon fibers, and even more preferably glass fibers. Preferably, the composition of the invention does not include continuous fibers. In a preferred embodiment, the composition of the invention does not include long reinforcing fibers, i.e. reinforcing fibers with a length greater than 400 pm. Plasticizer

[0135] The composition according to the invention may further comprise at least one plasticizer. The plasticizer content in the composition according to the invention is from 0 to 14% by weight relative to the total weight of the composition.

[0136] Plasticizers are, by way of example, selected from benzene sulfonamide derivatives, such as n-butyl benzene sulfonamide (BBSA); ethyl toluene sulfonamide or N-cyclohexyl toluene sulfonamide; esters of hydroxybenzoic acids, such as ethyl-2-hexyl parahydroxybenzoate and decyl-2-hexyl parahydroxybenzoate; esters or ethers of tetrahydrofurfuryl alcohol, such as oligoethyleneoxytetrahydrofurfuryl alcohol; and esters of citric acid or hydroxymalonic acid, such as oligoethyleneoxy malonate.

[0137] We would not depart from the scope of the invention by using a mixture of plasticizers.

[0138] In one embodiment, the plasticizer is present in the composition of 1 to 14% by weight, in particular from 1 to 12% by weight relative to the total weight of the composition.

[0139] In another embodiment, the plasticizer is present from 5 to 14%, in particular from 5 to 12% by weight relative to the total weight of the composition.

[0140] In a preferred embodiment, the composition of the invention does not include a plasticizer. Composition preparation process

[0141] The present invention also relates to a method for preparing a composition as described above.

[0142] In a first embodiment, the process for preparing the composition according to the invention comprises the steps of: i. Preparation of a masterbatch by dispersing graphene in a polyamide matrix; then ii. Mixing of the master mixture in the polyamide according to the invention comprising optional shock modifier, additive and plasticizer.

[0143] Preferably, at step (i) the graphene content is 10 to 50% by weight relative to the weight of the master mixture.

[0144] Advantageously, the polyamide of the master blend is identical to the polyamide of the composition according to the invention.

[0145] Preferably in step (ii) the masterbatch content is between 1 and 20% relative to the total weight of the mixture obtained in step (ii).

[0146] Preferably, in step (ii), the masterbatch and the polyamide are mixed in the molten state. The mixing can take place in any device for mixing, kneading, or extruding molten plastics known to those skilled in the art, such as an internal mixer, a roller mixer, an extruder, such as a single-screw extruder or a twin-screw counter- or co-rotating extruder, a co-mixer, such than a continuous co-mixer, or a stirred reactor. Preferably, the mixing takes place in an extruder or a co-mixer, more preferably in an extruder, even more preferably in a twin-screw extruder.

[0147] Preferably, the mixing in step (ii) is carried out at a temperature at least 10°C above the melting point of polyamide, preferably at a temperature at least 20°C above the melting point of polyamide, preferably at a temperature at least 30°C above the melting point of polyamide.

[0148] Advantageously, the mixing is carried out for a period of 30 seconds to 15 minutes, preferably from 40 seconds to 10 minutes. Preferably, the mixing is carried out under agitation.

[0149] Before their mixing in step (ii), the master mixture and the polyamide can independently be in powder or granule form.

[0150] Advantageously, the preparation process includes a step of shaping the mixture obtained in step (ii) into granules or powder. When the mixture is made into a powder, it is preferably first made into granules or flakes, and then the granules or flakes are ground into a powder. Any type of mill can be used, such as a hammer mill, a pin mill, an attrition disc mill, or an impact classifier mill.

[0151] In another embodiment, the composition according to the invention can be prepared, preferably in one step, by dispersing graphene in the polyamide according to the invention in the molten state, optionally in the presence of shock-modifying and / or plasticizing additives.

[0152] In this embodiment, the preparation process includes a step of shaping the resulting mixture into granules or powder. When the mixture is in powder form, it is preferably first formed into granules or flakes, and then the granules or flakes are ground into powder. Any type of mill can be used, such as a hammer mill, a pin mill, an attrition disc mill, or an impact classifier mill.

[0153] This second embodiment of the process is not preferred because it poses health risks (especially inhalation) due to the small size of the graphene particles.

[0154] Preferably, the composition according to the invention is not obtained by polymerizing polyamide in the presence of graphene. Indeed, such a process requires significant quantities of solvent and is therefore not preferred for environmental and economic reasons. Moreover, the use of graphene in the polymerization reactor contaminates said reactor. Single-layer or multi-layer structure

[0155] The present invention also relates to single-layer or multi-layer structures in which the layer in the case of the single-layer structure or at least one of the layers in the case of the multi-layer structure is formed in whole or in part from the composition according to the invention, preferably is made up of the composition according to the invention.

[0156] The structures according to the present invention are preferably intended for the transport, storage and / or distribution of fluid, in particular fluid for transport vehicles, in particular motor vehicles and other transport vehicles such as trains, trucks, subways, etc.

[0157] The term "motor vehicle" means any vehicle with an internal combustion, electric or

[0158] hybrid equipped with wheels or tracks, excluding a flying vehicle.

[0159] The motor vehicle may be two-wheeled, three-wheeled, four-wheeled or tracked.

[0160] For example, it is chosen from an electric bicycle, a moped, a motorcycle, a sidecar, a car, a van, a tractor, a truck, a bus, a coach, a snowmobile, a half-track, a bulldozer, a snow groomer, and a tank. In particular, it is chosen from a car, a van, a truck, a bus, and a coach.

[0161] The single-layer or multi-layer structures of the present invention may be tanks, pipes (or tubes), or liners. Throughout the description, the term "tube" or "pipe" may be used and refers to the same thing.

[0162] In one embodiment, the present invention relates to single-layer or multi-layer reservoir-type structures for fluid storage, comprising at least one layer obtained with the composition of the invention, preferably of which at least one layer is made up of the composition according to the invention.

[0163] In another embodiment, the present invention relates to single-layer or multi-layer tubular structures (MLT) for the transport and distribution of fluid, comprising at least one layer obtained with the composition of the invention, preferably comprising at least one layer made up of the composition of the invention.

[0164] Preferably, the multilayer structures comprise at least one other layer, preferably comprising a polyamide.

[0165] The multilayer structures according to the present invention (MLT or reservoir) comprise at least one layer obtained with the composition of the invention, preferably a layer made of the composition according to the invention, preferably this layer being the innermost layer (in contact with the fluid), and one or more other layers, for example, chosen from the group consisting of reinforcing layers (in particular, composite layers), sealing layers (barrier layers), the Chemical resistance layers, burst resistance layers, etc. These multilayer structures are well known to those skilled in the art.

[0166] The term "fluid" refers to a gas, particularly used in the automotive industry, or a liquid, particularly used in the automotive field. Examples of liquids include oil, brake fluid, urea solution, glycol-based coolant, fuels, particularly gasoline, diesel, LPG, bio-gasoline or biodiesel, and especially gasoline and, more particularly, ethanol-blended gasoline. The fluid according to the invention may also be hydrogen.

[0167] In a preferred embodiment, air, nitrogen and oxygen are excluded from the definition of said fluid.

[0168] In one embodiment, said fluid refers to fuels, in particular gasoline, especially alcoholic gasoline.

[0169] In another embodiment, said fluid refers to hydrogen.

[0170] The term "gasoline" refers to a mixture of hydrocarbons obtained from the distillation of petroleum to which additives or alcohols such as methanol and ethanol may be added, with alcohols being the major components in some cases.

[0171] The term "alcohol-based gasoline" refers to gasoline to which methanol or ethanol has been added. It also refers to E95 type gasoline which does not contain any petroleum distillation products.

[0172] In the present invention, the tank can be a tank for mobile hydrogen storage, i.e., on a truck for transporting hydrogen, on a car for transporting hydrogen and supplying hydrogen to a fuel cell, for example, on a train for refueling hydrogen, or on a drone for refueling hydrogen. It can also be a stationary hydrogen storage tank at a station for distributing hydrogen to vehicles. The tank can also be a tank for storing fuel or coolant.

[0173] In one embodiment, the multilayer structure according to the present invention may, for example, be a hydrogen tank and comprises or is made up of several layers, in particular two layers, excluding a film or granule. Generally, hydrogen tanks comprise at least one barrier layer (or sealing layer) and one reinforcing layer. Hydrogen tanks may comprise or be made up of, for example, several sealing layers and several reinforcing layers, or one sealing layer and several reinforcing layers, or several sealing layers and one reinforcing layer, or one sealing layer and one reinforcing layer.

[0174] The term "barrier layer" (or "sealing layer") refers to a layer These layers exhibit low permeability and good resistance to various fluid components, particularly fuels and hydrogen. In other words, the barrier layer slows the passage of the fluid, especially fuel (both its polar components, such as ethanol, and its nonpolar components, such as hydrocarbons) or hydrogen, into other layers of the structure or even outside of it. The barrier layer's primary function is therefore to prevent excessive fuel loss into the atmosphere through diffusion, thus mitigating air pollution.

[0175] Thus, the present invention preferably relates to: - a single-layer or multi-layer tubular structure, for the transport, distribution or storage of fluid, comprising at least one layer, preferably an inner layer, formed in whole or in part from the composition according to the invention, preferably comprising at least one layer, preferably an inner layer, made up of the composition according to the invention; - a single-layer tubular structure, for the transport, distribution or storage of fluid, formed in whole or in part from the composition according to the invention, preferably the single-layer tubular structure is made up of the composition according to the invention; - a multilayer tubular structure, for the transport, distribution or storage of fluid, comprising at least one layer, preferably an inner layer, formed in whole or in part from the composition according to the invention, preferably comprising at least one layer, preferably an inner layer, made up of the composition according to the invention and at least one other layer, preferably the other layer comprises a polyamide; - a single-layer or multi-layer tank for the transport or storage of fluid, comprising at least one layer, preferably an inner layer, formed in whole or in part from the composition according to the invention, preferably comprising at least one layer, preferably an inner layer, made up of the composition according to the invention; - a single-layer tank, for the transport or storage of fluid, formed in whole or in part from the composition according to the invention, preferably the single-layer tank is made up of the composition according to the invention; - a multilayer tank, for the transport or storage of fluid, comprising at least one layer, preferably an inner layer, formed in whole or in part from the composition according to the invention, preferably comprising at least one layer, preferably an inner layer, made up of the composition according to the invention and at least one other layer, preferably the other layer comprises a polyamide.

[0176] In one embodiment, the structures of the present invention can be used for the transport, distribution and storage of hydrogen (H2).

[0177] In another embodiment, the structures of the present invention can be used for the transport, distribution and storage of coolant.

[0178] In another embodiment, the structures of the present invention can be used for the transport, distribution and storage of fuel.

[0179] The present invention also relates to a method for preparing single-layer or multi-layer structures as described above comprising a step of manufacturing a sealing layer by injection, extrusion, extrusion-blowing or rotomolding implementing the composition according to the invention.

[0180] In one embodiment the structure is a multilayer structure and further includes a filament winding step of the reinforcing layer as defined above around the sealing layer as defined above. Use of the composition

[0181] The present invention also relates to the use of the composition according to the invention for manufacturing a single-layer or multi-layer structure, as described above. The single-layer or multi-layer structure is preferably obtained by a preparation step of at least one layer comprising the composition according to the invention by injection, extrusion, extrusion blow molding, or rotational molding using the composition of the invention. Other layers may also be present and, in particular, implemented simultaneously. Use of graphene

[0182] The present invention also relates to the use of 0.05 to 20% by weight, preferably 0.1 to 15% by weight, more preferably 0.1 to 5% by weight, even more preferably 0.1 to 2% by weight, of at least one polar graphene in a composition comprising at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, optionally up to 5% by weight of at least one additive, optionally up to 40% by weight of at least one shock modifier and / or optionally up to 14% by weight of at least one plasticizer, the percentages being given in relation to the total weight of the composition, to obtain an extractable rate less than or equal to 4g / m2, preferably less than or equal to 3g / m2.

[0183] The present invention also relates to the use of 0.05 to 20% by weight, preferably 0.1 to 15% by weight, more preferably 0.1 to 5% by weight, even more preferably 0.1 to 2% by weight, of at least one polar graphene, in a composition comprising at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, possibly up to 5% by weight of at least An additive, possibly up to 40% by weight of at least one shock modifier and / or possibly up to 14% by weight of at least one plasticizer, the percentages being given relative to the total weight of the composition, to obtain an extractable yield lower than that obtained for the same composition free of graphene. For the purposes of the present invention, the same graphene-free composition is understood to mean a comparative composition in which the graphene has been replaced by the same quantity of polyamide, all other things being equal. It should be understood that when the composition according to the invention comprises a polyamide blend, then the polyamide that replaces the graphene in the comparative composition is the same polyamide blend as that of the composition according to the invention in the same relative proportions.

[0184] In one embodiment, the extractable yield is determined by a test consisting of filling a tubular structure with FAM-B type alcoholic essence and heating the assembly at 60°C for 96 hours, then emptying the tube by filtering it into a beaker. The filtrate from the beaker is then allowed to evaporate at room temperature and the residue is weighed, thus giving the extractable yield per unit of internal tube surface area. This measurement method is notably described in standard TL52712.

[0185] Alcoholic spirits FAM B are described in DIN 51604-1:1982, DIN 51604-2:1984 and DIN 51604-3:1984. In short, alcoholic spirits FAM A are first prepared with a mixture of 50% toluene, 30% isooctane, 15% diisobutylene and 5% ethanol, and then FAM B is prepared by mixing 84.5% FAM A with 15% methanol and 0.5% water. In total, FAM B consists of 42.3% toluene, 25.4% isooctane, 12.7% diisobutylene, 4.2% ethanol, 15% methanol and 0.5% water.

[0186] The term extractable means all compounds from the composition forming the layers of the monolayer or multilayer structure and which can be carried away by the fluid, examples of extractables are plasticizers, monomers, oligomers, additives, etc.

[0187] The present invention also relates to the use of 0.05 to 20% by weight, preferably 0.1 to 15% by weight, more preferably 0.1 to 5% by weight, and even more preferably 0.1 to 2% by weight, of at least one polar graphene, in a composition comprising at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, optionally up to 5% by weight of at least one additive, optionally up to 40% by weight of at least one shock modifier, and / or optionally up to 14% by weight of at least one plasticizer, the percentages being given relative to the total weight of the composition, to obtain a permeability lower than that obtained for the same composition free of graphene. For the purposes of the present invention, the same composition free of graphene is understood to mean a a comparative composition in which graphene has been replaced by the same quantity of polyamide, all other things being equal. It should be understood that when the composition according to the invention comprises a polyamide blend, then the polyamide that replaces graphene in the comparative composition is the same polyamide blend as that of the composition according to the invention, in the same relative proportions.

[0188] The permeability according to the invention is the permeability of the monolayer or multilayer structure to the fluid.

[0189] In a particular embodiment, the measured permeability is the hydrogen permeability and is measured according to ISO 15105-2 at atmospheric pressure.

[0190] The definitions and contents of polyamide, graphene, shock modifier, plasticizer and additive mentioned above also apply.

[0191] The single-layer or multi-layer structures of the invention therefore exhibit good permeability, in particular permeability to hydrogen, and a low extractability rate. Recyclable

[0192] Particularly advantageously, the structures obtained with the composition of the invention are recyclable.

[0193] The term “recyclable” means that said mono- or multi-layer structure, after use and therefore after transport, distribution, or storage of fluids, can be reused, in particular after grinding, i.e., implemented in a manufacturing process for a part, in particular a new mono- or multi-layer structure, in particular by extrusion, while obtaining good mechanical properties, including cold impact resistance, high burst strength, and high elongation at break, unlike the recycling of a structure not containing graphene. For the purposes of the present invention, the term “even graphene-free composition” means a comparative composition in which the graphene has been replaced by the same quantity of polyamide, all other things being equal.It must be understood that when the composition according to the invention comprises a polyamide mixture, then the polyamide that replaces graphene in the comparative composition is the same polyamide mixture as that of the composition according to the invention in the same relative proportions.

[0194] The grinding is carried out according to the classic techniques of a person skilled in the art to a size of between 1mm and 2cm.

[0195] Said reuse of said used tubular structure may be carried out in mixture or not with virgin material.

Claims

Claims

1. Composition comprising, relative to the total weight of the composition: - At least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2; - From 0.05 to 20% by weight of a polar graphene; - From 3 to 40% by weight of at least one impact modifier.

2. Composition according to claim 1, further comprising: - Up to 5% by weight of at least one additive; and / or - Up to 14% by weight of at least one plasticizer; and / or - From 5 to 49% by weight of short reinforcing fibers.

3. Composition according to claim 1 or 2, in which the polar graphene is a graphene oxide or a graphene functionalized with at least one function reacting with the polyamide, preferably a function chosen from maleic anhydrides, carboxylic acids, primary amines, isocyanates, preferably maleic anhydrides and amines.

4. Composition according to any one of the preceding claims, in which the polar graphene has a number of oxygen atoms of between 50 and 99.9% relative to the total number of atoms of the graphene with the exception of any hydrogen atoms present in the graphene.

5. Composition according to any one of the preceding claims in which the polyamide is: - An aliphatic polyamide resulting from the polycondensation: • of at least one C6 to C18 amino acid, preferably C9 to C18, more preferably C10 to C18, even more preferably C10 to C12, in particular C11; or • of at least one C6 to C18 lactam, preferably C9 to C18, more preferably C10 to C18, even more preferably C10 to C12, in particular C12; or • of at least one C4-C36 aliphatic diamine Ca, in particular C6-C36, preferably C6-C18, preferentially C6-C12, more preferentially C10-C12 with at least one aliphatic diacid Cb in C4-C36, in particular in C6-C36, preferentially C6-C18, preferentially C10-C18, more preferentially C10-C12; or - A semi-aromatic polyamide of formula A / XT in which A is chosen from a unit obtained from an amino acid, a unit obtained from a lactam and a unit corresponding to the formula (Ce diamine).(Cd diacid), with c representing the number of carbon atoms of the diamine and d representing the number of carbon atoms of the diacid, c and d each being between 4 and 36, advantageously between 9 and 18, the unit (Ce diamine) being chosen from linear or branched aliphatic diamines, as defined above, cycloaliphatic diamines and alkylaromatic diamines and the unit (Cd diacid) being chosen from linear or branched aliphatic diacids, cycloaliphatic diacids and aromatic diacids; X.T denotes a unit obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 5 and 36, advantageously between 9 and 18, T corresponds to terephthalic acid.

6. Composition according to any one of the preceding claims in which the polyamide is: - An aliphatic polyamide chosen from PA6, PA66, PAU, PA12, PA610, PA612, PA1010, PA1012 and PA1212; - A semi-aromatic polyamide chosen from a PA MPMDT / 6T, a PA11 / 10T, a PA 5T / 10T, a PA 11 / BACT, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, PA BACT / 10T / 6T, a PA 11 / BACT / 6T, PA 11 / MPMDT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, PA 11 / MXDT / 10T, PA 11 / 5T / 10T, T corresponds to terephthalic acid, MXD corresponds to m-xylylene diamine, MPMD corresponds to methylpenta- methylenediamine and BAC stands for bis(aminomethyl)cyclohexane.

7. Composition according to any one of the preceding claims in which the impact modifier is chosen from olefin copolymers and in particular copolymers comprising ethylene or propylene units.

8. A single-layer or multi-layer structure wherein the layer in the case of the single-layer structure or at least one of the layers in the case of the multi-layer structure is formed in whole or in part from the composition as defined in any one of claims 1 to 7

9. / . Structure according to claim 8 characterized in that it is a tubular structure.

10. Structure according to claim 8 characterized in that it is a reservoir.

11. Use of the structure according to one of claims 8 to 10 for the transport, distribution and storage of a fluid.

12. Use according to claim 11, wherein the fluid is hydrogen.

13. Use according to claim 11, wherein the fluid is a coolant.

14. Use according to claim 11, wherein the fluid is a fuel.

15. Use of a composition according to any one of claims 1 to 7 for the manufacture of a single-layer or multi-layer structure by injection, extrusion, extrusion-blow molding or rotational molding, preferably by extrusion.

16. Use of 0.05 to 20% by weight of at least one polar graphene in a composition comprising at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, optionally up to 5% by weight of at least one additive, optionally up to 40% by weight of at least one impact modifier and / or optionally up to 14% by weight of at least one plasticizer, the percentages being given relative to the total weight of the composition, to obtain an extractable content of less than or equal to 4g / m2, preferably less than or equal to 3g / m2.

17. Use of 0.05 to 20% by weight of at least one polar graphene in a composition comprising at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, optionally up to 5% by weight of at least one additive, optionally up to 40% by weight of at least one impact modifier and / or optionally up to 14% by weight of at least one plasticizer, the percentages being given relative to the total weight of the composition, to obtain an extractable rate lower than that obtained for the same composition free of graphene in which the graphene has been replaced by the same quantity of the polyamide.

18. Use of 0.05 to 20% by weight of at least one polar graphene, in a composition comprising at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, optionally up to 5% by weight of at least one additive, optionally up to 40% by weight of at least one impact modifier and / or optionally up to 14% by weight of at least one plasticizer, the percentages being given relative to the total weight of the composition, to obtain a permeability lower than that obtained for the same composition free of graphene in which the graphene has been replaced by the same quantity of the polyamide.

19. Method of manufacturing a single-layer or multi-layer structure as defined according to one of claims 8 to 10, characterized in that it comprises a step of manufacturing a sealing layer by injection, extrusion, extrusion-blow molding or rotational molding.