Inflatable personal flotation device

Abstract

An inflatable personal flotation device (10) has at least one sheet of flexible material (72, 74) that includes graphene. The sheet of material further may include a polyurethane, PU, or thermoplastic polyurethane, TPU. The inflatable personal flotation device may include two sheets of material, one of which is provided to support the other and to form an inflatable bladder (58). The sheet of material may be formed from fibres, threads or yarn that contains graphene.

Description

INFLATABLE PERSONAL FLOTATION DEVICETECHNICAL FIELD

[0001] The present invention relates to inflatable personal flotation devices, such as garments, lifejackets and Life Preserver Unit (LPUs ) .BACKGROUND TO THE INVENTION

[0002] It is known to form inflatable personal flotation devices, such as lifejackets and LPUs , using flexible polymer films (e . g . polyurethane, PU, or thermoplastic polyurethane, TPU) to create waterproof and gas (e . g . air) holding materials .

[0003] The inflatable personal flotation device may include an inflatable bladder . In some cases the bladders are made of a textile (nylon or polyester) which is coated with an air-holding layer of an air impermeable material such as synthetic rubber (e . g . neoprene ) or thermo-plastic materials such as polyurethane (PU) and thermoplastic polyurethane (TPU) . Most bladders are now made of a TPU coated fabric type because TPU is a thermoplastic material which can be easily welded using high frequency or radio frequency or ultrasonic welding . The disadvantage of this type of bladder construction is that the bladders have poor characteristics in respect of weld strength, tear and tensile strength and are not Fire Resistant ( FR) and also may not be Moisture Vapour Permeable (MVP) .

[0004] The inflatable personal flotation device may also include an interior and exterior sheet of material, in which the inflatable bladder is contained. This sheet of material should be strong and fire resistant .

[0005] Inflatable personal flotation devices are used in many safety-critical roles - for example by aircrew. Aircrew and their flight equipment is subj ected to extremes of use and potential for damage which include the following :• Wear and tear as a result of the frequency of use and servicing and laundering . A flight garment may be worn and laundered several times in 24 hours which can cause excessive wear .• Entering and exiting the aircraft places greater strain on the equipment and the potential for snagging . Each time a pilot gets into the ej ector seat and straps in and tightens straps and buckles it places loads on the equipment .• If the pilot ej ects from the aircraft this can place great strain on the materials . The equipment may be required to be able to withstand the "air blast" resulting from meeting up to 700 knots air speed and unless the materials are strong enough they can be torn open. Also, during "air blast" the blast can include fragments of materials that can penetrate the equipment and puncture it resulting in it failing in use .• On landing on the ground and if escape and evasion is required then damage can be caused by the environment tearing or puncturing the inflatable personal flotation device .SUMMARY OF THE INVENTION

[0006] Some embodiments of the invention provide an inflatable bladder system in which the materials are reinforced with graphene and configured to be carried by an aircrew garment worn on the body of the aircrew and to apply pressure to provide buoyancy in the event of an emergency landing in water .

[0007] Some embodiments of the invention provide graphene reinforced garments worn by aircrew in flight . Reinforcing materials with graphene have been shown through testing to increase tensile and tear strength for a given thickness / weight of material, increase weld strength and increase Moisture Vapour Permeability (MVP) and give Flame Retardancy ( FR) characteristics .

[0008] A garment may provide an outer layer (a restrainer) that holds and positions and restrains inflatable bladder (s ) such that when they are inflated they provide buoyancy. In some embodiments, the outer layer that restrains the bladder is made from a textile that incorporates graphene reinforced fibres . Previously the garment outer retraining layer was made from a woven textile such as nylon or polyester . A disadvantage of these outer restraining layers is that they may ultimately fail and tear . Conventionally, the only way to overcome this is to use a heavier more substantial material and this in turn makes the garment heavier, bulkier and to have a greater thermal ( FR) burden. Furthermore, the restrainer is preferably made of a material that is fire retardant and in some cases a "sacrificial layer" of a FR material, adding further to the weight and bulk of the system, is used . The textile restrainer reinforced with graphene is inherently FR and requires no outer FR covering . The combination of the graphene inflatable bladders with the outer graphene retainers can provide buoyancy with increased strength and durability and / or reduced weight and bulk .

[0009] As mentioned above, a disadvantage of conventional TPU bladder construction is that the bladders have poor characteristics in respect of weld strength, tear and tensile strength and are not FR and also may not be moisture vapour permeable (MVP) . In some embodiments of this invention a bladder system is provided whereby the TPU and the supporting textile ( if the TPU is coated onto a textile) include materials that are reinforced with graphene . The graphene may be either incorporated into the TPU when it is being mixed and into the textile yarn material when it is being mixed before being extruded. Conventionally, to achieve the same level of strength in tear and tensile and weld strength, the weight / thickness of the TPU would have to be greater that the graphene reinforced TPU. The graphene bladders are therefore lighter and less bulky and are inherently FR and have greater MVP characteristics . In the case of such flight garments then the additional strengthand resilience of the materials for a given weight is very important .

[0010] According to one aspect of the invention, there is provided an inflatable personal flotation device having at least one sheet of flexible material that includes graphene .

[0011] Graphene can be defined as a lattice of hexagonal carbon atoms having a single layer of atoms arranged in a honeycomb planar nanostructure . Graphene Nano Platelets (GNPs ) can be defined as platelet-shaped sheets of graphene stacked on top of one another . These graphitic stacks may have an average thickness of 1-2 nanometres . GNPs may possess many of the same properties as graphene . The graphene in the at least one sheet of flexible material, according to various embodiments of the invention, may be in the form of GNPs or other forms of graphene, including pure graphene .

[0012] The sheet of material may also include polyurethane, PU, and / or thermoplastic polyurethane, TPU . Graphene may be dispersed into PU / TPU at the melt stage in the form of GNPs .

[0013] The sheet of material may be formed from fibres that contain graphene, threads that contain graphene or yarn that contains graphene . The fibres, threads or yarn may be woven together to form the sheet of material . The fibres, threads or yarn may also include polyurethane, PU, and / or thermoplastic polyurethane, TPU . Graphene may be dispersed into PU / TPU at the melt stage in the form of GNPs .

[0014] Embodiments of the invention may provide an inflatable personal flotation device using flexible polymer films (e . g . PU or TPU) incorporating graphene to create waterproof and / or gas (e . g . air) holding materials . Such incorporation of graphene into the PU / TPU film may increase its strength and contributes to the overall performance of the equipment .

[0015] Embodiments of the invention may provide aninflatable personal flotation device using one of more sheets of material, e . g . including PU or TPU, and incorporating graphene . Such incorporation of graphene into the sheet of material may increase its strength and flame retardance, and contributes to the overall performance of the equipment .

[0016] The sheet of material may be fluid impermeable . This allows the sheet of material to form a pressure holding inflatable item. Pressure holding inflatable items are normally referred to as "bladders" . Inflatable bladders can be inflated orally by mouth or from a compressed gas source such as a cylinder of compressed CO2 .

[0017] For example, an inflatable personal flotation device may utilise a film of a flexible polymer typically for example PU or TPU in order to provide a barrier against a pressurised gas in the creation of inflatable structures .

[0018] A flexible polymer, typically for example PU or TPU, film incorporating graphene may also be used to create a flexible material which is waterproof .

[0019] The sheet of material may have a thickness of between 100 and 150pm - as this would typically be the film / sheet thickness for use in Life Preserver Unit (LPU) applications .

[0020] The sheet of material may include between 1 and 10% graphene (by weight ) , preferably 1.5% graphene by weight . Samples of a number of different percentages of graphene by weight ranging from 1% to 5% were tested in four ways - being breaking force, puncture resistance, weld strength and tear strength. The most effective percentage of GNPs within the TPU was found to be 1.5% .

[0021] The sheet of material may be moisture-vapour permeable . This may improve comfort of a garment and allow the passage of perspiration through the material .

[0022] The sheet of material may be flame retardant (e . g .it will be less damaged by fire than a non-graphene including sheet of material) .

[0023] The inflatable personal flotation device may have at least one further non-graphene sheet of material (i . e . a sheet of material that does not contain graphene) . The non-graphene sheet of material may support the sheet of flexible material that includes graphene . The sheet of flexible material that includes graphene may have a lower modulus of elasticity the non-graphene sheet of material . The non-graphene supporting sheet of material may limit the expansion or stretching of the sheet of flexible material that includes graphene (e . g . as a bladder incorporating the sheet of flexible material that includes graphene ) . The non-graphene supporting sheet of material may protect the sheet of flexible material that includes graphene from abrasion or other damage . Alternatively, the supporting sheet of material may include graphene, and the sheet of material supported by the supporting sheet of material may or may not include graphene .

[0024] The sheet of material may form at least part of a garment, such as a flight suit configured to cover at least a part of a wearer' s body in use .

[0025] The garment may be a garment worn by an aircrew member and having a purpose of protecting the aircrew member during normal fight . Conventionally, a life jacket is worn over a protection garment to provide buoyancy to support the aircrew member' s body on water . The protection garment may be a garment worn in other marine applications when protection from drowning is desirable - such as on board a ship or oil rig .

[0026] The claimed garment may render a conventional lifej acket unnecessary, as the claimed protection garment itself provides buoyancy. Providing buoyancy by an inflatable chamber of the garment, rather than by a lifejacket, reduces the number of items the aircrew member (or other personnel) must wear . Thisreduces bulk, snagging hazards and the time taken for the aircrew member to get ready for flight .

[0027] The garment may have protective qualities for the wearer during normal use (that is , when not in water) - such as being fire-retardant or water-resistant . The garment may be configured to protect an aircrew member from fire, high G-acceleration and / or effects of altitude . The garment may be a flight vest or a flight suit, or perform the functions conventionally performed by a flight vest or a flight suit .

[0028] The garment may extend at least over the wearer' s chest and back, and behind their neck. The coverage of the wearer' s body by the garment may correspond to that of a conventional flight vest or suit .

[0029] In an embodiment of the invention the inflatable chamber functions as a life jacket or life preserver unit . The buoyancy required to save the wearer from drowning can be provided by the protection garment itself (by the inflatable chamber thereof ) . A conventional lifejacket / life preserver, which is not a garment or part of a garment, unit can therefore be dispensed with .

[0030] The garment may include triggering means for automatically triggering inflation of the inflatable chamber on contact with water - e . g . a hydrostatic triggering mechanism. Additionally, or alternatively, the inflation of the inflatable chamber may be triggerable manually - e . g . by the aircrew member operating a lever .

[0031] In an embodiment of the invention the inflatable chamber extends over the wearer' s chest and behind their neck . Such an arrangement provides buoyancy at desired locations to prevent the wearer from drowning . The inflatable chamber, when uninflated, covers only a portion of the area of the protection garment - e . g . the inflatable chamber does not cover the back of the wearer, which is covered by the garment .

[0032] The inflatable chamber may be located beneath an outer layer of the garment when deflated, wherein the outer layer includes a line of weakness that opens due to pressure applied by partial inflation of the inflatable chamber to allow full inflation of the inflatable chamber outside the outer surface of the garment . The line of weakness may be formed by a releasable coupling, which may be a burst-open zipper .

[0033] The inflatable chamber may be located between the outer and an inner layer of the garment when deflated . The inner layer is preferably adj acent to the wearer' s torso . The outer and / or inner layer of the garment may include graphene, which may increase strength and improve fire retardancy.

[0034] The outer and inner layers may be substantially inelastic, thereby forming a substantially inelastic pocket for the inflatable chamber . The inelasticity of the pocket causes pressure from inflation of the inflatable chamber to be applied to the releasable coupling, rather than expanding the pocket .

[0035] The inflatable chamber may be an inner chamber layer and an outer chamber layer, wherein the inner chamber layer is separate from the outer chamber layer . The inner chamber layer and / or the outer chamber layer may include graphene, which may increase strength and improve fire retardancy. The configuration of the inflatable chamber as described and claimed may provide a strong and low-bulk inflatable chamber . This is highly advantageous as the garment may have low bulk despite the inclusion of the inflatable chamber . This may increase comfort and safety for the wearer .

[0036] According to another aspect of the present invention there is provided a personal protection garment configured to cover at least a part of a wearer' s body in use, wherein the protection garment includes an inflatable chamber configured to provide buoyancy to support the wearer' s body on water when inflated to save the wearer from drowning, and wherein thepersonal protection garment has at least one sheet of flexible material that includes graphene .

[0037] According to a further aspect of the present invention there is provided a method of protecting a person from drowning, the method including providing the person with a protection garment configured to cover at least a part of the person' s body and to protect the person during normal use, wherein the protection garment includes an inflatable chamber configured to provide buoyancy to support the person' s body on water when inflated to prevent the person from drowning, and wherein the protection garment has at least one sheet of flexible material that includes graphene, the method including inflating the inflatable chamber on contact with the water, or when contact with water is expected, so that the buoyancy protects the person from drowning .

[0038] The protection provided by the garment in normal use may be protection that is not related to immersion in water -so as protect from fire or cold.

[0039] In the method the protection garment may be as defined above .

[0040] According to an embodiment of the invention, it is proposed is to position a life preserver bladder inside the protective garment (e . g . flight acket / waistcoat ) with breakout zippers or the like, that enable inflation of the life preserver bladder, fitted directly to the front of the garment . The life preserver bladder breaks open the zipper due to the pressure exerted by inflation of the bladder . The bladder then passes through the hole made by the zipper opening up .

[0041] This embodiment has maj or advantages to the cosmetic appearance of the ensemble . Instead of a life preserver being fitted over a protection garment (as in a known arrangement) , a protection garment is fitted with a life preserver that is not visible when uninflated. The embodiment also removes the bulkaway from the top of the wearer' s shoulders, the front chest and behind the neck eliminating restrictions to head mobility and helmet interaction. When used with new lighter weight (micro ) life preserver designs and a Remote Inflation System (e . g . as described in the applicant' s patent GB2573474 ) , the presence of the uninflated life preserver may be practically imperceptible to the wearer . The use of graphene allows the bulk and weight to be further reduced for a given garment strength .

[0042] Due to the reduced packed size, items such as remote antennas , lights , etc . , that can normally be fitted to the life preserver bladder, may need to be moved and alternative solutions introduced .

[0043] Embodiments of the present invention address one of the biggest issues identified with current life preserver designs : bulk, and restrictions to head mobility and snagging potential .

[0044] Embodiments of the present invention may be used in marine and special forces applications . The proactive garment may be a flight suit but could be a garment providing protection in another context .

[0045] Because the inflatable chamber is built-in to the garment, the wearer will always be protected from drowning when they wear the garment . In contrast, if a separate garment and lifejacket are used, the lifejacket may be forgotten or deliberately not worn .

[0046] All of the features described herein may be combined with any of the above aspects, in any combination .

[0047] Inflatable personal flotation devices comprising conventional films or sheets of material (without graphene reinforcement) have a number of disadvantageous features ; these include limited tensile strength, limited resistance to impact damage, low modulus (modulus of elasticity) , low thermalstability and poor flame retardancy. Studies have shown that by incorporating graphene into a sheet or film (e . g . a PU / TPU film) it is possible to improve a number of characteristics of the sheet or film to the overall advantage of the equipment' s performance . For example see : "Chemical Engineering Journal" Vol 482 15thFebruary 2024 "The Reinforcement of Polyurethane by Mini-Sized Graphene with Superior Performances" . Such laboratory studies have indicated that the inclusion of graphene in PU material can provide the following benefits to the PU film and therefore to the equipment :Improved tensile strength by up to 80%Modulus by up to 126%Increased mechanical performanceIncreased shape memoryThe PU film can be fire retardant and generate limited smoke

[0048] Bladders incorporating graphene (and e . g . PU / TPU) , according to embodiments of the invention have been manufactured and tested and found to have the following improvements over the same non-Graphene bladders :Average breaking force increased by 40%Average puncture resistance improved by 10%Average weld strength improved by 39%Average tear strength improved by 10%

[0049] Reducing the weight of the product is very advantageous both for personal safety equipment (e . g . lif e j ackets ) . The thickness and therefore the weight of the PU / TPU film can be reduced while still achieving the same or better strength characteristics of the non-graphene PU film.

[0050] Additionally reducing the thickness of a grapheneincluding PU / TPU sheet or film may make it more flexible and therefore easier to pack into a more compact space thereby further saving space and weight .BRIEF DESCRIPTION OF THE DRAWINGS

[0051] For a better understanding of the presentntion embodiments will now be described by way of example, with reference to the accompanying drawings , in which :Fig . 1 is a cross-section of an inflatable personal flotation device;Figs . 2 to 7 are partial views at points around the circumference of the inflatable personal flotation device of Fig . 1 - e . g . at points A, B or C - showing different forms of pieces of material that may be used to form the inflatable personal flotation device;Figs . 8 , 9 and 10 are partial views at points around the circumference of the inflatable personal flotation device showing how two pieces of material and may be sealed at their seams in various different ways ;Fig . 11 shows a front view of a lifejacket;Fig . 12 is a cross-section taken along line X-X of Fig . 11;Fig . 12A shows an enlarged view of part of one piece of material of the lifej acket body of Figs 11 and 12 ;Fig . 12B shows an enlarged view of a seam between two pieces of material of the lifejacket body of Figs 11 and 12 ;Fig . 13 shows a front view of a lifejacket;Fig . 14 is a cross-section taken along line Y-Y of Fig . 13 ;Fig . 14A shows an enlarged view of part of one piece of material of the lifej acket body of Figs 13 and 14 ;Fig . 14B shows an enlarged view of a seam between two pieces of material of the lifejacket body of Figs 13 and 14 ;Fig . 15 shows a front elevational view of a known flight ensemble comprising a protective flight garment over which a lifej acket is worn;Fig . 16 shows a left side view of the protective flight garment and lifejacket of Fig . 15 (other side corresponds ) ;Fig . 17 shows a rear elevational view of theprotective flight garment and life j acket of Fig . 15 ;Fig . 18 shows a cross-section taken along line A-A of Fig . 15 ;Fig . 19 shows a front elevational view of the protective flight garment and life acket of Fig . 15 after the lifej acket is inflated;Fig . 20 shows a left side view of the protective flight garment and lifej acket of Fig . 15 after the lifej acket is inflated ( other side corresponds ) ;Fig . 21 shows a cross-section taken along line A-A of Fig . 19 ;Fig . 22 shows a front elevational view of protective flight garment according to an embodiment of the invention;Fig . 23 shows a left side view of the protective flight garment of Fig . 22 ( other side corresponds ) ;Fig . 24 shows a rear elevational view of the protective flight garment of Fig . 22 ;Fig . 25 shows a cross-section taken along line A-A of Fig . 22 and 23 , including a partially enlarged view, as indicated by the arrow "A" ;Fig . 26 shows a front elevational view of the protective flight garment of Fig . 22 after its inflatable chamber is inflated;Fig . 27 shows a left side view of the protective flight garment of Fig . 22 after its inflatable chamber is inflated is inflated ( other side corresponds ) ;Fig . 28 shows a cross-section taken along line A-A of Figs . 26 and 27 ;Fig . 29A shows a cross-sectional view of an inflatable chamber according to an embodiment of the invention;Fig . 29B shows an enlarged detailed view of the layers of the inflatable chamber of Fig . 29A; andFig . 29C shows an enlarged view of the inflatable chamber of Fig . 29A where the upper and lower layers are connected .

[0052] In the drawings , like elements are generally designated with the same reference signs .DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0053] A inflatable personal flotation device according to various embodiments has at least one sheet of flexible material that includes graphene . The sheet of flexible material may also include a flexible polymer - such as polyurethane, PU, and / or thermoplastic polyurethane, TPU.

[0054] The sheet of flexible material may be formed by dispersing graphene in the form of Graphene Nano Platelets (GNPs ) into PU / TPU at the melt stage . The sheet of material may have a thickness of between 100 and 150pm. The sheet of material may include between 1 and 10% graphene by weight, preferably 1.5% graphene by weight .

[0055] The sheet of material may be formed from fibres , threads or yarn that contains graphene . The fibres, threads or yarn may be woven together to form the sheet of material . The fibres, threads or yarn may also include polyurethane, PU, and / or thermoplastic polyurethane, TPU . Graphene may be dispersed into PU / TPU at the melt stage in the form of GNPs to from the fibres , threads or yarn .

[0056] Embodiments of the invention may provide inflatable personal flotation devices, such as garments , lifejackets and LPUs , using flexible polymer films (e . g . PU or TPU) incorporating graphene to create waterproof and / or gas (e . g . air) -holding materials . Such incorporation of graphene into the PU / TPU film may increase its strength and flame retardancy, and may contribute to the overall performance of the equipment .

[0057] The graphene-including sheet of material may be fluid impermeable . This allows the sheet of material to form a pressure-holding inflatable item and / or to form a waterproof garment / item.

[0058] Pressure-holding inflatable items are often referredto as "bladders" . Inflatable bladders can be inflated orally by mouth or from a compressed gas source such as a cylinder of compressed CO2 .

[0059] Embodiments of the invention may provide inflatable personal flotation devices using one of more sheets of material . The sheet of material may be formed from fibres , threads or yarn that contains graphene . The fibres , threads or yarn may be woven together to form the sheet of material . The fibres , threads or yarn may include PU or TPU, and incorporate graphene . Such incorporation of graphene into the fibres, threads or yarn of the sheet of material may increase the strength of the sheet and flame retardancy, and contributes to the overall performance of the equipment .

[0060] An inflatable personal flotation device may include inflatable structures . An inflatable personal flotation device may be sealed against water ingress .

[0061] A graphene-including flexible sheet of material may be incorporated into an inflatable personal flotation device in a number of ways . By way of example, an inflatable personal flotation device 10 is shown in Fig . 1. The inflatable personal flotation device 10 includes two pieces of flexible material 12A and 12B . The pieces of flexible material 12A and 12B are connected to each other along opposite sides by a first seam 14A and a second seam 14B . The pieces of flexible material 12A and 12B form an inflatable bladder 16. The inflatable bladder 16 may be inflated, for example, by a gas inflation system 18 or by an oral inflation device 20. The inflatable bladder 16 may be circular in cross-section but may also have other cross-sectional shapes, such as elliptical .

[0062] Figs . 2 to 7 show different ways in which a grapheneincluding flexible sheet of material may be incorporated into the inflatable personal flotation device 10. Figs . 2 to 7 are partial views at any point around the circumference of the inflatable personal flotation devicelO of Fig . 1 - e . g . at points A, B or C .

[0063] In Fig . 2 each of the two pieces of flexible material 12A and 12B may be formed by a graphene-including flexible sheet of material 22 that is coated or laminated onto an inner face 24 of a supporting substrate 26 such as a woven textile (e . g . coated or laminated onto the entire inner face 24 of the supporting substrate 26 ) . The flexible sheet of material 22 creates a barrier to gas when the bladder 16 is filled and pressurised with gas . The outer textile supporting substrate 26 provides strength, abrasion resistance and limits the elasticity of the bladder 16 to create a dimensionally stable structure . Such an arrangement may be used, for example, as part of a life jacket (e . g . the life preserver as described in WO-A-2020 / 079025 ) . The supporting substrate 26 may be a non-graphene sheet of material ( i . e . a sheet of material that does not contain graphene) .

[0064] The supporting substrate 26 of Fig . 2 may be a graphene-containing sheet of material . The supporting substrate 26 may be formed by weaving together fibres , threads or yarn that contain graphene . In an arrangement where the supporting substrate 26 of Fig . 2 is a graphene-containing sheet of material, the flexible sheet of material 22 may be formed by a graphene-including flexible sheet or may be formed by a nongraphene sheet ( i . e . a sheet of material that does not contain graphene) .

[0065] In Fig . 3 each of the two pieces of flexible material 12A and 12B may be formed by a graphene-including flexible sheet of material 22 that is coated or laminated onto an outer face 28 of an inner supporting substrate 26A, such as a woven textile (e . g . coated or laminated onto the entire outer face 28 of the inner supporting substrate 26A) . The flexible sheet of material 22 creates a barrier to gas when the bladder 16 is filled and pressurised with gas . The inner supporting substrate 26A provides strength and limits the elasticity of the bladder 16 to create a dimensionally stable structure . The inner supporting substrate 26A may be a non-graphene sheet of material (i . e . asheet of material that does not contain graphene) . The flexible sheet of material 22 may protect the inner supporting substrate 26A from damage . The flexible sheet of material 22 may provide an outer surface onto which other items formed of PU / TPU may be readily attached - e . g . by high-frequency welding .

[0066] The inner supporting substrate 26A of Fig . 3 may be a graphene-containing sheet of material . The inner supporting substrate 26A may be formed by weaving together fibres, threads or yarn that contain graphene . In an arrangement where the inner supporting substrate 26A of Fig . 3 is a graphene-containing sheet of material, the flexible sheet of material 22 may be formed by a graphene-including flexible sheet or may be formed by a non-graphene sheet (i . e . a sheet of material that does not contain graphene) .

[0067] In Fig . 4 each of the two pieces of flexible material 12A and 12B may be formed by a graphene-including flexible sheet of material 22 that is coated or laminated onto an inner face 24 of an outer supporting substrate 26B ( such as a woven textile ) and coated or laminated onto an outer face 28 of an inner supporting substrate 26A ( such as a woven textile ) . For example, the flexible sheet of material 22 is coated or laminated onto the entire inner face 24 of an outer supporting substrate 26B and coated or laminated onto the entire outer face 28 of an inner supporting substrate 26A. The flexible sheet of material 22 is sandwiched between an inner and outer supporting substrates 26A, 26B . The flexible sheet of material 22 creates a barrier to gas when the bladder 16 is filled and pressurised with gas . The inner supporting substrate 26A provides strength and limits the elasticity of the bladder 16 to create a dimensionally stable structure . The outer supporting substrate 26B provides strength, abrasion resistance and limits the elasticity of the bladder 16 to create a dimensionally stable structure . The inner supporting substrate 26A and / or the outer supporting substrate 26B may be a non-graphene sheet of material ( i . e . a sheet of material that does not contain graphene) .

[0068] The inner supporting substrate 26A of Fig . 4 may be a graphene-containing sheet of material . The inner supporting substrate 26A may be formed by weaving together fibres, threads or yarn that contain graphene . Alternatively, or additionally, outer supporting substrate 26B of Fig . 4 may be a graphenecontaining sheet of material . The outer supporting substrate 26B A may be formed by weaving together fibres, threads or yarn that contain graphene . In an arrangement where the inner supporting substrate 26A and / or the outer supporting substrate 26B of Fig .4 is a graphene-containing sheet of material, the flexible sheet of material 22 may be formed by a graphene-including flexible sheet or may be formed by a non-graphene sheet (i . e . a sheet of material that does not contain graphene) .

[0069] In Fig . 5 each of the two pieces of flexible material 12A and 12B may be formed by an inner graphene-including flexible sheet of material 22 and an outer sheet 30 such as a woven textile (similar to the supporting substrate 26 of Fig . 2 ) . However, in this embodiment, the flexible sheet of material 22 is not attached to outer sheet 30 but is unsupported. The flexible sheet of material 22 may be within but completely separate from the outer sheet 30. The flexible sheet of material 22 may be connected to the outer sheet 30 at one or more points which form a minority of the surface area of the outer sheet 30. The outer sheet 30 forms a non-elastic outer "restrainer" which has smaller dimensions than the potential dimensions of the chamber formed by the flexible sheet of material 22 when expanded . The non-elastic outer "restrainer" retains its dimensional stability so that it does not expand when the chamber formed by the graphene-including flexible sheet of material 22 is inflated . Such an arrangement may be used, for example, as part of a lifejacket that needs to be very compact when deflated and packed. The outer sheet 30 may be a non-graphene sheet of material (i . e . a sheet of material that does not contain graphene) .

[0070] The outer sheet 30 of Fig . 5 may be a graphenecontaining sheet of material . The outer sheet 30 may be formed by weaving together fibres, threads or yarn that contain graphene . In an arrangement where the outer sheet 30 of Fig . 5 is a graphene-containing sheet of material, the flexible sheet of material 22 may be formed by a graphene-including flexible sheet or may be formed by a non-graphene sheet (i . e . a sheet of material that does not contain graphene) .

[0071] In Fig . 5 the chamber formed by the flexible sheet of material 22 may be made to be oversize or made from a material that can stretch and so that any join in the chamber (e . g . welds or seams between multiple flexible sheets of graphene-containing material ) never comes under tension . Although the chamber may be of generally the same shape as the non-elastic outer "restrainer", the chamber may be of generally larger size . The chamber may be made of a sufficiently large size so that, when inflated within the non-elastic outer "restrainer", the chamber fills the internal volume of the non-elastic outer "restrainer" without any stretching of the chamber occurring, and the tension is taken up by the non-elastic outer "restrainer" . If the chamber is made oversized, the chamber may be made of an inextensible and / or inelastic material . It is advantageous for the tension to be taken up by the non-elastic outer "restrainer", as it may generally be stronger than the chamber .

[0072] In Fig . 6 each of the two pieces of flexible material 12A and 12B is formed by a graphene-including flexible sheet of material 22. In this embodiment graphene-including flexible sheet of material 22 is not supported in any way and forms a single layer pressurised bladder (no sheet such as a woven textile or the like is provided) . The graphene-including flexible sheet of material 22 may provide an outer surface onto which other items formed of PU / TPU may be readily attached -e . g . by high-frequency welding .

[0073] In Fig . 7 each of the two pieces of flexible material 12A and 12B may be formed by two graphene-including flexiblesheets of material 22A and 22B . Inner flexible sheet of material 22A is coated or laminated onto an inner face 24 (e . g . onto the entire inner face 24 ) of a supporting substrate 26 ( such as a woven textile) . Outer flexible sheet of material 22B is coated or laminated onto an outer face 28 (e . g . onto the entire outer face 28 ) of the supporting substrate 26. The supporting substrate 26 is "sandwiched" between the inner and outer flexible sheets of material 22A and 22B . The flexible sheets of material 22A and 22B create barriers to gas when the bladder 16 is filled and pressurised with gas . The supporting substrate 26 provides strength and limits the elasticity of the bladder 16 to create a dimensionally stable structure . The flexible sheets of material 22A and 22B provide redundancy, so that the gastight nature of the bladder may be maintained when one of the flexible sheets of material 22A and 22B is damaged. The supporting substrate 26 may be a non-graphene sheet of material ( i . e . a sheet of material that does not contain graphene ) . The outer flexible sheet of material 22B may protect the supporting substrate 26 from damage . The outer flexible sheet of material 22B may provide an outer surface onto which other items formed of PU / TPU may be readily attached - e . g . by high-frequency welding .

[0074] The supporting substrate 26 of Fig . 7 may be a graphene-containing sheet of material . The supporting substrate 26 may be formed by weaving together fibres , threads or yarn that contain graphene . In an arrangement where the supporting substrate 26 of Fig . 7 is a graphene-containing sheet of material, the flexible sheets of material 22A and / or 22B may be formed by a graphene-including flexible sheet or may be formed by a non-graphene sheet (i . e . a sheet of material that does not contain graphene) .

[0075] Although in the arrangements described above, each of the two pieces of flexible material 12A and 12B may be formed by a graphene-including flexible sheet of material 22 , it should be understood that only one of the pieces of flexible material12A and 12B may formed by a graphene-including flexible sheet of material 22 (the other piece of flexible material may be gas-impermeable but not include graphene ) .

[0076] An inflatable personal flotation device may use a graphene-including flexible sheet of material 22 to create a barrier to water or other liquids when used for example in immersion survival suits . The graphene-including flexible sheet of material can be incorporated into the equipment structure in one of the six ways above in Figs . 2 to 7 .

[0077] An inflatable personal flotation device may use a graphene-including flexible sheet of woven material 26, 26A, 26B to improve strength, flame retardancy, and / or abrasionresistance when used for example in immersion survival suits . The graphene-including flexible woven sheet of material can be incorporated into the equipment structure in one of the six ways above in Figs . 2 to 7 .

[0078] The graphene-including flexible sheet of material 22 can be made MVP (Moisture Vapour Permeable ) , termed "breathable", if required . For example, the graphene-including flexible sheet of material 22 may have a molecular structure that allows moisture vapour to pass through but that does not allow water to pass through .

[0079] Typically, such inflatable personal flotation devices are formed from a plurality of pieces of flexible material, such as the pieces of material 12A and 12B of the inflatable personal flotation device 10 described above . The pieces of material may include (or consist of ) graphene-including flexible sheets of material, such as the graphene-including flexible sheet of material 22 and / or flexible sheet of woven material 26, 26A, 26B of the inflatable personal flotation device described above . Edges of one or more pieces of material may be connected together to form an inflatable personal flotation device .

[0080] Pieces of material 12A and 12B may be sealed at their seams ( such as the seams 14A and 14B described above) in various ways . Pieces of material may be sealed at their seams by being glued or welded (e . g . welded together by high frequency welding) . The seams can be "in shear", peel or peel and shear, as shown in Figs . 8 , 9 and 10, respectively.

[0081] By way of example, Fig . 8 shows a partial view of the inflatable personal flotation device 10 described above in the region of the seam 14B . The two generally semicircular (in crosssection) pieces of material 12A and 12B are brought together, with edges 40A and 40B of the pieces of material 12A and 12B extending radially outwardly with respect to the generally circular (in cross-section) main body of the inflatable personal flotation device 10 so that they lie adjacent to one another and in parallel . The seam 14B is formed by welding or gluing (or otherwise fixing together) the edges 40A and 40B of the pieces of material 12A and 12B . The weld (or adhesive) between the edges 40A and 40B of the pieces of material 12A and 12B is designated 42. The seam 14A may be formed in the same way. Such seams as shown in Fig . 8 can be referred to as "in peel" .

[0082] By way of example, Fig . 9 shows a partial view of the inflatable personal flotation device 10 described above in the region of the seam 14B . The two generally semicircular (in crosssection) pieces of material 12A and 12B are brought together, with edges 40A and 40B of the pieces of material 12A and 12B overlapping . The upper piece of material 12A has an outer surface 43A and an inner surface 43B . The lower piece of material 12B has an outer surface 45A and an inner surface 45B . The pieces of material 12A and 12B are connected at an edge region 40A and 40B of each of the pieces of material 12A and 12B so that the distal inner surface of one of the pieces overlaps the distal outer surface of the other one of the pieces . In the arrangement shown the distal outer surface 43A of the upper piece of material 12A is positioned to face the distal portion of the inner surface 45B of the lower piece of material 12B .

[0083] The seam 14B is formed by welding or gluing (or otherwise fixing together) the edges 40A and 40B of the pieces of material 12A and 12B . The weld (or adhesive) between the edges 40A and 40B of the pieces of material 12A and 12B is designated 42. The seam 14A may be formed in the same way. Such seams as shown in Fig . 9 can be referred to as "in shear" .

[0084] By way of example, Fig . 10 shows a partial view of the inflatable personal flotation device 10 described above in the region of the seam 14B . The two generally semicircular ( in cross-section) pieces of material 12A and 12B are brought together, with edges 40A and 40B of the pieces of material 12A and 12B extending radially inwardly with respect to the generally circular (in cross-section) main body of the inflatable personal flotation device 10 so that they lie adjacent to one another and in parallel . The seam 14B is formed by welding or gluing (or otherwise fixing together) the edges 40A and 40B of the pieces of material 12A and 12B, and by welding or gluing (or otherwise fixing) a strip of material 47 over the outer surface of the inflatable personal flotation device 10 in the region where the pieces of material 12A and 12B meet . The weld (or adhesive ) between the edges 40A and 40B of the pieces of material 12A and 12B, and between the strip of material 47 over the outer surface of the inflatable personal flotation device 10 in the region where the pieces of material 12A and 12B meet, is designated 42. The seam 14A may be formed in the same way. Such seams as shown in Fig . 10 can be referred to as "in peel" and "in shear" .

[0085] Inflatable personal flotation devices are used to provide buoyancy to prevent a wearer drowning . An inflatable personal flotation device may be an inflatable lifej acket, such as an LPU. An advantage of the use of inflatable lifejackets , as opposed to permanently buoyant life j ackets using buoyant material rather than a gas, is that inflatable lifej ackets can be of a small size prior to inflation, allowing them to be worn without encumbering the wearer or creating a thermal burden . However, the materials of the lifej acket, particularly anyinflatable bladder, need to be robust and strong because these lifej ackets will be donned and doffed frequently, kept in unclean conditions and roughly handled, used and stored in a range of extreme temperatures, and packed and repacked for maintenance and servicing . Additionally, the life jackets may need to be flame and fire retardant and resistant to UV exposure and if used in an aircraft with an ejector seat system will need to be able to withstand wind blast .

[0086] Referring to Fig . 11, there is shown an inflatable personal flotation device, such as a lifejacket 51. The lifejacket 51 comprises a body 52 that is generally horse-shoe shaped and is for fitting around a wearer ' s neck . The body 52 comprises first and second inflatable buoyancy sections 53 and 54 which form generally symmetrically disposed legs of the horse-shoe, arranged to lie on opposite sides of a wearer ' s torso . First ends of the first and second buoyancy sections 53 , 54 are joined together by a neck portion 55. The first and second buoyancy sections 53, 54 each extend from said first end to a second end, which is a free end . The first and second buoyancy sections 53, 54 , together with the neck portion 55 , define an aperture 56 for receiving a wearer ' s head and neck .

[0087] The lifejacket body 52 is formed from first and second pieces of material sealed together along a seam 57 , towards a peripheral edge, to define a body inflation chamber 58. The pieces of material protrude from the seam 57 to form an edge 60.

[0088] When inflated, each buoyancy section 53, 54 is an elongate member of generally oval cross section . The inflation chamber 58 is connected to an inflation cartridge 59, containing compressed gas, that can be manually or automatically actuated. Following actuation, the inflation cartridge inflates the body inflation chamber 58 .

[0089] Each buoyancy section 53, 54 is provided with a mouth-operable inflator in the form of a tube 62 connected to theinterior of the body inflation chamber 58. This allows manual inflation of the body inflation chamber 58 in the event of failure of the inflation cartridge 59. Each tube 62 is provided with a non-return valve and a closure cap to prevent water flowing down the tube and into the body inflation chamber 58.

[0090] In use the first and second buoyancy sections 53, 54 lie on opposite sides respectively of a wearer ' s chest, in a side-by-side relationship .

[0091] Fig . 12 is a cross-section taken along line X-X of Fig . 11. Fig . 12A shows an enlarged view of part of one piece of material of the lifej acket body 52 . Fig . 12B shows an enlarged view of a seam between two pieces of material of the lifejacket body 52.

[0092] As mentioned above, the lifejacket body 52 is formed from first and second pieces of material 64 , 66 sealed together along a seam 57 , towards a peripheral edge, to define a body inflation chamber 58. Each of the first and second pieces of material 64 , 66 consists of an outer textile supporting sheet 72 (for example including nylon or polyester) coated or laminated on the inside with a sheet 74 of flexible, gas (e . g . air) impermeable material . The sheet 74 of flexible, gas impermeable material may include graphene, as discussed above . The sheet 74 may also include a polymer such as neoprene, polyurethane or TPU, as discussed above . The outer textile supporting sheet 72 may include graphene fibres , threads or yarn, as discussed above . The sheet outer textile supporting sheet 72 may also include a polymer such as neoprene, polyurethane or TPU, as discussed above . Each of the first and second pieces of material 64 , 66 may have a structure and composition as described in relation to any of Figs . 2 to 7 .

[0093] The coated two pieces of material 64 , 66 are typically j oined at its edges by welding or gluing the material together to form a seam 57. The seam shown is "in peel" (see Fig . 8 ) , although it should be understood that the seam may be "in shear" ( see Fig . 9 ) or both "in peel" and "in shear" (see Fig . 10 ) .

[0094] Another type of life j acket has a bladder made with an outer "restrainer" which is not bonded onto the bladder . Fig .13 shows a front view of an example of such inflatable lifejacket 82 . Fig . 14 shows a cross-section taken along line Y-Y of Fig .13. Fig . 14A shows an enlarged view of part of one piece of material of the life jacket 52. Fig . 14B shows an enlarged view of a seam between two pieces of material of the lifejacket 82. The lifejacket 82 has an outer cover 83, which forms a cover over a bladder 84 which is packed tightly inside it . An inflation system 86, which comprises a compressed gas cylinder 85 and an activation mechanism 87 , is mounted directly onto the outer cover 83.

[0095] The bladder 84 is formed by one or more sheets 94A, 94B of gas impermeable material . The one or more sheets 94A, 94B of gas impermeable material may include graphene, as discussed above . The sheets 94A, 94B may also include a polymer such as neoprene, polyurethane or TPU . The outer cover 83 is the nylon outer "restrainer" . The outer cover 83 may include two (or more ) pieces of material 83A, 83B that are j oined together at a seam 99. The pieces of material 83A, 83B may be woven and include graphene fibres, threads or yarn, as discussed above . The pieces of material 83A, 83B may also include a polymer such as neoprene, polyurethane or TPU, as discussed above . A life acket made in this way can be folded and packed into a more compact cover because two layers (the outer "restrainer" and the bladder) are more flexible than a single layer made up of two sheets bonded together .

[0096] As shown in Figs . 14 , 14A and 14B, an outer textile outer layer 83 (for example nylon or polyester with graphene) may be formed of two sheets of material 83A, 83B that are stitched together . An upper sheet of material 83A has an outer surface 97A and an inner surface 97B . The lower sheet of material 83B has an outer surface 98A and an inner surface 98B . The sheets 83A and 83B are connected at an edge region of each of the sheets so that the distal inner surface of one of the sheets overlapsthe distal outer surface of the other one of the sheets , the distal surfaces being stitched together, as indicated at 88 to form the seam 99. In the arrangement shown, the distal inner surface 97B of the upper sheet of material 83A is positioned to face the distal portion of the outer surface 98A of the lower sheet of material 83B, these sheets being held in contact by the stitching 88 .

[0097] The bladder 84 is formed by two sheets 94A, 94B or flexible gas impermeable material that may include graphene . The two sheets are joined by a weld 101 (or any other attachment technique ) .

[0098] In this embodiment the outer textile 83 is stitched ( in shear) around its edge and this creates a much stronger seam than the welding . The bladder 84 is made to be oversize or made from a material that can stretch and so the welded edge 101 never comes under tension, as shown in Figs . 14 , 14A and 14B . Although the bladder 84 may be of generally the same shape as the outer textile 83, the bladder 84 may be of generally larger size . The bladder 84 may be made of a sufficiently large size so that, when inflated within the outer textile 83 , the bladder 84 fills the internal volume of the outer textile 83 without any stretching of the bladder 84 occurring, and the tension is taken up by the outer textile 83. If the bladder 84 is made oversized, the bladder 84 may be made of an inextensible and / or inelastic material . It is advantageous for the tension to be taken up by the outer textile 83 , as it may be stronger than the bladder 84.

[0099] The outer textile layer 83 may include a lightweight "ripstop" material and is coated with a lubricant such as silicone . The outer textile layer 83 may be a lightweight material that includes graphene and is coated with a lubricant such as silicone . This may produce an extremely strong material with high tear strength, and also, because the surface has a very low surface friction, the inner polymer layer will slide easily over it which results in a very compact lifej acket .

[0100] Ripstop fabrics are woven fabrics, e . g . made ofnylon, using a special reinforcing technique that makes them resistant to tearing and ripping . During weaving, relatively thick reinforcement threads are interwoven at regular intervals in a crosshatch pattern . The intervals are typically 5 to 8 mm. Thin and lightweight ripstop fabrics have a 3-dimensional structure due to the thicker threads being interwoven in thinner cloth . The ripstop fabric may be modified to include graphenecontaining fibres , threads or yarn, as discussed above .

[0101] In the embodiment of Figs . 13 to 14B an inflatable chamber includes an inner layer and an outer layer, wherein the inner layer is separate from the outer layer . The outer layer comprises two sheets that are material that are stitched together "in sheer" . A low friction material may be provided between the inner layer and the outer layer (either or both of which may include graphene ) . The outer layer may be substantially inelastic . In the embodiment of Figs . 13 to 14B the inner layer and the outer layer may be as described in relation to Figure 5 .

[0102] The inflatable bladder' s strength is determined by the tensile strength and puncture resistance as well as the strength of the seam 101 (weld strength) which is typically constructed by high frequency welding . The welding process can produce a weakness in the film of the bladder which will cause the bladder to burst if the pressure is increased significantly but this weakness is greatly reduced if the bladder is made with graphene in it .

[0103] The arrangement of Figs . 14 , 14A and 14B provides a lifejacket that has an outer textile layer 83 that is separate from the bladder 84. This may be contrasted with a conventional lifej acket that uses a single layer of material that consists of a textile supporting sheet ( for example nylon or polyester) coated or laminated on the inside with a sheet of flexible, gas impermeable polymer such as neoprene or polyurethane . The coated two-layer material is typically stiff because of the relative thickness of the material and it is typically joined at itsedges by welding or gluing the material together to form a seam. The resistance of the bladder to bursting from over pressure is dependent on the strength of the weld in peel and the strength of the welded or glued seam is only as strong as the bonding of the polymer layer to the supporting textile . Furthermore, when the outer textile is coated with the polymer its tear strength is greatly reduced and therefore a stronger and thicker textile must be used .

[0104] Although these embodiments have been described in relation to a lifejacket as shown in Figs . 11 to 14 , it should be appreciated that least one sheet of flexible material that includes graphene may be advantageously incorporated into many other forms of lifej acket .

[0105] Aircrew members such as pilots wear an ensemble including a protective flight garment (e . g . , a flight suit or vest) when flying in aircraft . Traditionally the suit is either a single piece suit combining both j acket and trousers in a single garment or it is a two-piece suit with a separate jacket and trousers .

[0106] The protective garment may include special equipment (Aircrew Life Support Equipment - ALSE) that protects the wearer against the effects of high G-acceleration or altitude and other potentially damaging factors . Because of the potential of injury caused by fire in such aircraft then the protective garment must pass flame tests using "Burn Manikins" or other testing .

[0107] When flying their aircraft over water, the pilot and crew typically have a life preserver unit (e . g . a lifejacket ) which is usually attached to and worn over the protective flight garment, the ensemble comprising the protective flight garment and life preserver unit .

[0108] Traditional designs of life preservers that are worn around the wearer' s neck can cause bulk and restriction to head movement and in aviation applications they can cause interactionwith the aircrew helmets, further reducing head mobility and causing displacement of the helmet . In addition, the prominent bulk over the shoulders and on the front chest area can reduce downward visibility and become a snagging hazard when attempting aircraft escape .

[0109] Similar disadvantages arise in other situations where it is desired to protect a wearer from drowning - for example personnel on board a ship or oil rig who might fall into, or have to evacuate into, the sea - where a separate protection garment and life j acket create undesirable bulk .

[0110] Referring first to Figures 15 , 16 or 17 , a known aircrew ensemble 108 includes a protective flight garment 110 that in this example is a flight vest (but could instead be a j acket or full body suit) that is worn by an aircrew member (which could be any person on board an aircraft) . The flight garment 110 has a waist portion 112 , a neck opening 114 , and left and right arm holes 116A and 116B, respectively. The flight garment 110 also has a front opening 118 closed by, for example, a conventional zipper . The flight garment 110 may include an inherently fireproof fabric such as NOMEX®.

[0111] The flight garment 110 carries equipment pockets 120. The flight garment 110 also carries a waist belt 122 . The waist belt 122 may be secured at the front of the torso by a buckle 123 or any other suitable coupling .

[0112] As shown in Figures 15 , 16 or 17 , the aircrew ensemble 108 includes a lifejacket 130 that is worn over, and may be attached to, the flight garment 110. The lifej acket 130 , in the example shown, is generally U-shaped and has a central portion 132 that passes around the back of the wearer' s neck and two arms 134A and 134B extending from opposite left- and right-hand sides of the central portion 132 configured to lie over opposite sides in front of the wearer' s torso 131. Other shapes and configurations of life jacket are possible .

[0113] The lifejacket 130 is fitted with one or more inflation systems 133, such as a compressed gas cylinder for inflating a bladder (as shown at 152 in Figure 18 ) within the lifej acket 130.

[0114] The lifejacket 130 is typically attached to the flight garment 110 in two or three or more places .

[0115] In the example shown, at the front torso the lifejacket 130 is attached to the flight garment 110 by a pair of zippers 138A and 138B . This attachment is important in aircrew use as they may experience "wind blast" if ej ecting from an aircraft at speed which could detach the lifejacket 130 if it is not securely attached to the flight garment 110.

[0116] A left-hand side zipper 138A has a first row of teeth extending longitudinally along the inner side of the left arm 34A of the lifejacket 130 and a corresponding second row of teeth extending longitudinally along the front of the flight garment 110 generally parallel and spaced to the left of the opening 118 of the flight garment 110. The left arm 134A of the lifej acket 130 is attached to the flight garment 110 by drawing a slider (not shown) of the zipper 138A upwards, which draws the first and second rows of teeth together in the conventional manner of operation of a zipper .

[0117] Similarly, a right-hand side zipper 138B has a third row of teeth extending longitudinally along the inner side of the right arm 134B of the lifejacket 130 and a corresponding fourth row of teeth extending longitudinally along the front of the flight garment 110 generally parallel and spaced to the right of the opening 118 of the flight garment 110. The right arm 134B of the lifejacket 130 is attached to the flight garment 110 by drawing a slider (not shown) of the zipper 138B upwards , which draws the third and fourth rows of teeth together in the conventional manner of operation of a zipper .

[0118] Alternative attachment arrangements to zippers may be used to attach the lifejacket 130 at the front torso to the flight garment 110 , such as by buckles or the like .

[0119] In the example shown, the arms 134A and 134B of the lifejacket 130 are attached to the waist belt 122 at points 135A and 135B (see Figure 18 ) at the left- and right-hand sides of the wearer' s torso, respectively. This attachment may be by the waist belt 122 passing through a respective loop (not shown) attached to the underside of the left arm 134A and to the underside of the right arm 134B the life acket 130. These form strong anchoring points when the lifejacket 130 is inflated .

[0120] A back strap 126 is attached at its lower end to the waist belt 122 (e . g . by lifej acket loop 140 - see Figure 16 and 18 ) at the centre of the rear torso and is attached to the lifej acket 130 at its upper end at the central portion 132 at the back of the neck . This may prevent the lifejacket 130 riding up over the wearer' s head when inflated . The back strap 126 may be threaded through the channel 124 of the flight garment 110 to further locate the back strap 126, as shown in Figure 17 .

[0121] As shown in Figure 18 , the lifejacket 130 has a cover 150 which protects an inflatable bladder 152 , which is packed inside the cover 150, from damage . The inflation system 133 can be contained within the cover 150 (as shown in Figure 15 and 18 ) or can be remote from the cover 150 and connected by a tube to the bladder 152 (a Remote Inflation System) .

[0122] When the lifejacket inflation system 133 is activated, the cover 150 will automatically open either by way of an automatically releasable closure 154 , such as a "burst open" zipper, Velcro® or press studs etc . When the life jacket inflation system 133 is activated (either manually or automatically) , the inflating bladder 152 acts on the automatically releasable closure 154 to open it . Figures 19, 20and 21 show the bladder 152 when fully inflated, after the automatically releasable closure 154 has opened.

[0123] According to an embodiment of the invention, rather than having an aircrew ensemble that includes a lifejacket that is worn over a protective flight garment, the protective flight garment itself carries a buoyancy-providing inflatable bladder and no separate lifejacket is required. That is , the inflatable bladder is integrated into the protective flight garment that is worn on the body of the wearer .

[0124] Referring first to Figures 22 , 23 and 24 , a novel protective flight garment 210 that in this example is a flight vest (but could instead be a jacket or full body suit) is provided. The flight garment 210 may include an inherently fireproof fabric such as NOMEX®. The flight garment 210 may include NOMEX® in combination with graphene . The flight garment 210 may include another material in combination with graphene .

[0125] The protective flight garment 210 may include special equipment (Aircrew Life Support Equipment - ALSE) that protects the wearer against the effects of high G-acceleration or altitude and other potentially damaging factors .

[0126] The flight garment 210 has a waist portion 212 , a neck opening 214 , and left and right arm holes 216A and 216B, respectively. The flight garment 210 also has a front opening 218 closed by, for example, a conventional zipper . When the front opening 218 is closed, the flight garment 210 is securely attached to the body of the wearer .

[0127] The flight garment 210 carries equipment pockets 220. The flight garment 210 also carries a waist belt 222 . The waist belt 222 may be secured at the front of the torso by a buckle 223 or any other suitable coupling . The waist belt 222 may include graphene . The buckle 223 may include graphene .

[0128] The flight garment 210 in the embodiment extends atleast over the aircrew member' s chest and back, and behind their neck .

[0129] As shown in Figures 22 , 23 and 24 , the flight garment 210 has a region 219 in which a deflated inflatable bladder -or inflatable chamber - 252 (see Figure 25 ) is accommodated. The region 219, in the example shown, is generally U-shaped and has a central portion 232 that passes around the back of the wearer' s neck and two arms 234A and 234B extending from opposite left-and right-hand sides of the central portion 232 configured to lie over opposite sides in front of the wearer' s torso 231. The inflatable bladder 252 may include one or more sheets of material that comprise graphene ( for example, in combination with PU or TPU) .

[0130] The deflated bladder 252 has a similar shape and size to the region 219, so that deflated bladder 252 is also generally U-shaped and has a central portion that passes around the back of the wearer' s neck and with two arms extending from opposite left- and right-hand sides of the central portion configured to lie over opposite sides in front of the wearer' s torso 231. The deflated bladder 252 may be folded to fit in the region 219.

[0131] Other shapes and configurations of the region 219 and the bladder 252 are possible .

[0132] The region 219 is fitted with one or more inflation systems 233 , such as a compressed gas cylinder for inflating the bladder 252 within the region 219. The inflation system 233 may be automatically triggered on contact with water and / or may be manually triggered by the aircrew member . The inflation system 233 may include graphene .

[0133] In the example shown, the arms 234A and 234B of the bladder 252 are attached to the waist belt 222 at strong attachment points 235A and 235B (see Figure 25 ) at the left- and right-hand sides of the wearer' s torso, respectively. Thisattachment may be by the waist belt 222 passing through a respective loop (not shown) attached to the underside of the left arm of the bladder and to the underside of the right arm of the bladder . The attachment points 235A and 235B form strong anchoring points when the bladder 252 is inflated. The waist belt 222 may be integrated into the garment 210.

[0134] A back strap 226 may be attached at its lower end to the waist belt 222 (e . g . by loop 240 - see Figure 23 and 25 ) at the centre of the rear torso and is attached to the bladder 252 at its upper end at the central portion 232 at the back of the neck. This may prevent the bladder 252 riding up over the wearer' s head when inflated. The back strap 226 may be threaded through the channel (not shown) of the flight garment 210 to further locate the back strap 226. The back strap 226 may be integrated into the garment 210 or may be omitted (as shown in Figure 24 ) . The back strap 226 may include graphene . The loop 240 may include graphene .

[0135] As shown in Figure 25 , the bladder 252 is packed deflated inside the outer surface (exterior or front layer) 250 of the flight garment 210, to protect the bladder 252 from damage . The inflation system 233 can be contained beneath the outer surface 250 or can be remote from the outer surface 250 and connected by a tube to the bladder 252 (e . g . by a Remote Inflation System, e . g . as described in the applicant' s patent GB2573474 ) .

[0136] An internal cover ( interior or rear layer) 256 can be fitted to protect the bladder 252 inside the garment . The internal cover 256 lies between the bladder 252 and the torso 231 of the wearer . The internal cover 256 is preferably substantially inelastic . The internal cover 256 may be formed from an inelastic woven material . The generally inelastic nature of the internal cover 256 means that it does not expand significantly when the bladder 252 is inflated . As a consequence, inflation of the bladder 252 applies pressure tothe automatically releasable closure 254 , rather than expanding the internal cover 256. The internal cover 256 may include graphene .

[0137] Similarly, the outer surface (exterior surface) 250 of the garment 210 may also be formed of a substantially inelastic material, such as an inelastic woven material . The generally inelastic nature of the outer surface 250 means that it does not expand significantly when the bladder 252 is inflated. As a consequence, inflation of the bladder 252 applies pressure to the automatically releasable closure 254 , rather than expanding the outer surface 250.

[0138] Together, the internal cover 256 and the outer surface (exterior surface) 250 of the flight garment 210 form a pocket 259 within which the deflated bladder 252 is contained. The area where both the internal cover 256 and the outer surface (exterior surface) 250 are present corresponds to the region 219 in which a deflated inflatable bladder 252 is accommodated.

[0139] The internal cover 256 and / or the outer surface (exterior surface) 250 of the flight garment 210 may be a graphene-containing sheet of material . The internal cover 256 and / or the outer surface (exterior surface) 250 may be formed by weaving together fibres, threads or yarn that contain graphene .

[0140] The internal cover 256 has a similar shape and size to the region 219, so that the internal cover 256 is also generally U-shaped and has a central portion that passes around the back of the wearer' s neck and with two arms extending from opposite left- and right-hand sides of the central portion configured to lie over opposite sides in front of the wearer' s torso 231.

[0141] Openings 260 may be provided in the internal cover 256 at locations in each of its arms that correspond to the position of the waist belt 222. The waist belt 222 may passthrough the openings 260 so that the strong attachment points 235A and 235B, where the arms and of the bladder 252 are attached to the waist belt 222 , are inside the pocket 259. A total of four openings 260 may be provided, two in each arm.

[0142] The outer surface 250 of the flight garment 210 is provided with an automatically releasable closure 254 in the region 219, e . g . in the centre of the region 219. The automatically releasable closure 254 may be a "burst open" zipper, Velcro® or press studs etc . The automatically releasable closure 254 may be a slide fastener as described in the applicant' s patent publication GB2588110. The automatically releasable closure 254 extends along the two arms 234A and 234B and the central portion 236, behind the wearer' s neck .

[0143] When the inflation system 233 is activated, the outer surface 250 will automatically open by way of the automatically releasable closure 254 . When the inflation system 233 is activated (either manually or automatically) , the inflating bladder 252 acts on the automatically releasable closure 254 to open it . The pressure generated by inflation of the bladder 252 causes the automatically releasable closure 254 to open . When the automatically releasable closure 254 opens, the bladder 252 passes through the opening as further inflation occurs . Figures 26, 27 and 28 show the bladder 152 when fully inflated, after the releasable closure 154 has opened.

[0144] Figures 26, 27 and 28 depict the bladder 252 after it has moved from the interior of the garment 210 (as shown in Figures 22 to 25 ) to the exterior of the garment 210 as it inflates . The inflated bladder is positioned over the wearer' s chest and behind the wearer' s neck and provides buoyancy, thereby preventing drowning in the event that the aircrew member makes an emergency landing in water .

[0145] The internal cover 256 or the outer surface 250 may be opened by a releasable closure 258 (e . g . formed by pressstuds, a conventional zipper or Velcro®) to allow the bladder 252 to be removed from the garment 210 for maintenance or repair . Unlike the automatically releasable closure 254 , the releasable closure 258 is not configured to open automatically when the bladder 252 is inflated .

[0146] In this embodiment, instead of using a conventional single layer of material that consists of a textile supporting sheet ( for example nylon or polyester with graphene) coated or laminated on the inside with a sheet of flexible gas (e . g . air) impermeable polymer such as neoprene or polyurethane with graphene, the two separate layers may be provided (e . g . a textile outer layer and the separate inner polymer layer) to form the bladder 252. The textile outer layer and / or the separate inner polymer layer may include graphene . The bladder may be formed of layers as described in relation to Figure 5. The bladder layers may be connected as described in relation to Figures 8 to 10 .

[0147] The use of two separate layers to make the bladder 252 may result in a bladder construction that is lighter, more compact when packed and stronger .

[0148] As shown in Figures 29A-C, a textile outer layer 352 ( for example nylon or polyester) of the bladder 252 may be formed of two sheets of material that are stitched together . An upper sheet of material 353A has an outer surface 357A and an inner surface 357B . The lower sheet of material 353B has an outer surface 358A and an inner surface 358B . The sheets 353A and 353B are connected at an edge region 359 of each of the sheets so that the distal inner surface of one of the sheets overlaps the distal outer surface of the other one of the sheets, the distal surfaces being stitched together, as indicated at 361. In the arrangement shown the distal inner surface 357B of the upper layer 357A is positioned to face the distal portion of the outer surface 358A of the lower layer 353B, these layers being held in contact by the stitching 361.

[0149] An inner layer 355 of the bladder 252 is formed by two sheets 354 of flexible gas impermeable material . The two sheets are joined by a weld 356.

[0150] In this embodiment the outer textile layer 352 can be stitched ( in sheer) around its edge and this creates a much stronger seam than the welding . The inner layer of the bladder 252 is made to be oversize or made from a polymer that can stretch and so the welded edge 356 never comes under tension, as shown in Figures 29A-C . Although the inner layer 355 of the bladder 252 may be of generally the same shape as the outer textile layer 352 , the inner layer 355 of the bladder 252 may be of generally larger size . The inner layer 355 of the bladder 252 may be made of a sufficiently large size so that, when inflated within the outer textile layer 352 , the inner layer 255 of the bladder 252 fills the internal volume of the outer textile layer 352 without any stretching of the inner layer 355 of the bladder 252 occurring, and the tension is taken up by the outer textile layer 352. If the inner layer of the bladder 252 is made oversized, the inner layer 355 of the bladder 252 may be made of an inextensible and / or inelastic material . It is advantageous for the tension to be taken up by the outer textile layer 352 , as it is stronger than the inner layer of the bladder 252 .

[0151] Preferably, the outer textile layer 352 is made from a lightweight "ripstop" material and is coated with a lubricant such as silicon. The outer textile layer 352 may be a lightweight material that includes graphene and is coated with a lubricant such as silicone . This produces an extremely strong material with high tear strength, and also, because the surface has a very low surface friction, the inner polymer layer 355 will slide easily over it which results in a very compact lifej acket .

[0152] Ripstop fabrics are woven fabrics, e . g . made of nylon, using a special reinforcing technique that makes them resistant to tearing and ripping . During weaving, relativelythick reinforcement threads are interwoven at regular intervals in a crosshatch pattern . The intervals are typically 5 to 8 mm. Thin and lightweight ripstop fabrics have a 3-dimensional structure due to the thicker threads being interwoven in thinner cloth. The fabric may contain graphene in addition to, or instead of ripstop material .

[0153] In the above embodiment the LPU bladder is mounted on the interior face of a jacket or vest, suit etc . (i . e . a garment ) , but on activation of the inflation moves from the interior to the exterior of the garment via an automatically opening zipper or Velcro or press studs etc . as a result of the bladder being pressurised.

[0154] The protection garment may be a garment worn by an aircrew member and having a purpose of protecting the aircrew member during normal fight - as described in the embodiment above . The protection garment may alternatively be a garment worn in other applications when protection from drowning is desirable - such as on board a ship or oil rig .

[0155] Embodiments of the invention provide inflatable personal floatation devices with graphene reinforcement . For aircrew particularly, but also some other military applications, reducing bulk and weight to an absolute minimum but at the same time maintaining strength and durability is highly advantageous . Using graphene as described may provide these advantages . The use of graphene may maintain durability with repeated packing and servicing as well as providing resistance to damage caused by air-blast on ej ection . The use of graphene in LPU integrated into a garment is highly advantageous because of reduced bulk and weight . For navy applications the reduced bulk is important when used by personnel in SAS / SBS boarding and clandestine operations , and carrying and "shouldering" weapons .

Claims

CLAIMS1. An inflatable personal flotation device having at least one sheet of flexible material that includes graphene .2 . The inflatable personal flotation device of claim 1, wherein the graphene included in the sheet of flexible material comprises the graphene nano platelets .

3. The inflatable personal flotation device of claim 1 or 2 , wherein the sheet of material further includes a flexible polymer .4 . The inflatable personal flotation device of claim 1 , 2 or 3 , wherein the sheet of material includes polyurethane, PU .5 . The inflatable personal flotation device of any one of claims 1 to 4 , wherein the sheet of material includes thermoplastic polyurethane, TPU.

6. The inflatable personal flotation device of any one of claims 1 to 5 , wherein the sheet of material includes between 1 and 10% graphene by weight, preferably 1.5% graphene by weight .7 . The inflatable personal flotation device of any one of claims 1 to 6, wherein the sheet of material has a thickness of between 100 and 150pm.8 . The inflatable personal flotation device of any one of claims 1 to 7 , wherein the sheet of material is fluid impermeable .

9. The inflatable personal flotation device of any one of claims 1 to 8 , wherein the sheet of material is moisturevapour permeable .

10. The inflatable personal flotation device of any one of claims 1 to 9, wherein the sheet of material is formed fromfibres, threads or yarn that contains graphene .

11. The inflatable personal flotation device of claim 10, wherein the fibres , threads or yarn are woven together to form the sheet of material .12 . The inflatable personal flotation device of any one of claims 1 to 11 , including first and second sheets of material, one of which comprises said at least one sheet of flexible material that includes graphene .

13. The inflatable personal flotation device of claim 12 , wherein the first sheet of material is arranged to support the second sheet of flexible material .14 . The inflatable personal flotation device of claim 12 or 13 , wherein the second sheet of flexible material has a lower modulus of elasticity than the first sheet of material .15 . The inflatable personal flotation device of claim 12 , 13 or 14 , wherein the second sheet of flexible material is bonded to the first sheet of material .

16. The inflatable personal flotation device of claim 12 , 13 or 14 , wherein the second sheet material is separate from the first sheet of material .17 . The inflatable personal flotation device of any one of claims 12 to 16, wherein the second sheet of material flexible material forms at least part of an inflatable bladder .18 . The inflatable personal flotation device of claim 17 when dependent on claim 15 or 16, wherein first sheet of material is configured to limit the expansion of the inflatable bladder .

19. The inflatable personal flotation device of any one of claims 12 to 18 , wherein the first and / or second sheet of flexible material includes graphene .

20. The inflatable personal flotation device of any one of claims 1 to 19, comprising at least part of a garment configured to cover at least a part of a wearer' s body in use .

21. The inflatable personal flotation device of claim 20, including an inflatable chamber that functions as a lifej acket or life preserver unit, LPU .22 . The inflatable personal flotation device of claim 20 or 21, wherein the garment is a flight vest or flight suit .

23. The inflatable personal flotation device of claim 21 or 22 , wherein the inflatable chamber is located under an outer garment layer of the garment when deflated, wherein the outer garment layer includes a line of weakness that opens due to pressure applied by partial inflation of the inflatable chamber to allow full inflation of the inflatable chamber outside the outer garment layer of the garment .24 . The inflatable personal flotation device of claim 23 , wherein the inflatable chamber is located between the outer garment layer and an inner garment layer of the garment when deflated.25 . The inflatable personal flotation device of claim 23 or 24 , wherein the sheet of flexible material that includes graphene forms the outer garment layer and / or the inner garment layer .

26. The inflatable personal flotation device of any one of claims 21 to 25 when dependent on claim 17 or 18 , wherein the inflatable chamber comprises the inflatable bladder .27 . The inflatable personal flotation device of any one of claims 1 to 26, wherein the sheet of flexible material that includes graphene forms at least part of an inflatable device having a drop stitch structure .28 . The inflatable personal flotation device of any one of claims 1 to 19 or 27 , wherein the inflatable personal flotation device is a lifejacket or a life preserver unit, LPU.

29. The inflatable personal flotation device of any one of claims 1 to 28 , wherein the sheet of flexible material that includes graphene is connected to another sheet of material by an in shear and / or in peel connection .

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