METHOD AND APPARATUS FOR PROVIDING A FIBER-REINFORCED COMPOSITE MATERIAL

Abstract

A method of providing a fibre-reinforced composite material, the method comprising: dispersing particles of a first polymeric composition comprising a first thermoplastic in a liquid comprising water, thereby forming a dispersion; coating, at least in part, a first set of reinforcement fibres with the dispersion; redistributing the particles of the first polymeric composition comprised in the coating; and melting at least some of the redistributed particles of the first polymeric composition comprised in the coating, thereby providing the composite material.

Claims

1.-17. (canceled)

18. A PAEK thermoplastic polymer having a median particle diameter (D50) of 1 m to 100 m.

19. The PAEK thermoplastic polymer according to claim 18, wherein the D50 is 2.5 m to 75 m, such as 5 m to 60 m, or 7.5 m to 15 m.

20. The PAEK thermoplastic polymer according to claim 18, wherein the particles have a D10 of 4 m to 6 m, a D50 of 7 pin to 13 m, and a D90 of 15 m to 25 m.

21. The PAEK thermoplastic polymer according to claim 18, wherein the particles have a D10 of about 5 m, a D50 of about 10 m, and a D90 of about 20 m.

22. The PAEK thermoplastic polymer according to claim 18, wherein the polymer is a PEEK-based copolymer.

23. The PAEK thermoplastic polymer according to claim 18, wherein the tensile elongation of the polymer is about 15%.

24. The PAEK thermoplastic polymer according to claim 18, wherein the flexural strength of the polymer is about 150 MPa.

25. The PAEK thermoplastic polymer according to claim 18, wherein the flexural modulus of the polymer is about 3.3 GPa.

26. A dispersion of a PAEK thermoplastic polymer according to claim 18 in a liquid.

27. The dispersion according to claim 26, wherein the dispersion comprises particles of the PAEK thermoplastic polymer in a range from 2.5 to 50 wt % by weight of the dispersion.

28. A fibre-reinforced composite material comprising a first set of reinforcement fibres, surrounded by a first polymeric composition comprising a PAEK thermoplastic polymer according to claim 18; wherein a volume fraction of the first set of fibres is in a range from 50% to 70% by volume of the composite material.

29. The fibre-reinforced composite material according to claim 28, wherein the median particle diameter D50 of the PAEK thermoplastic polymer is in a range from 0.5d.sub.f to 4d.sub.f, wherein d.sub.f is the diameter of the first set of reinforcement fibres.

30. The fibre-reinforced composite material according to claim 28, wherein the median particle diameter D50 of the PAEK thermoplastic polymer is in a range from d.sub.f to 2d.sub.f.

31. The fibre-reinforced composite material according to claim 28, wherein the fibre-reinforced composite material has a void volume in a range from 0.001% to 5% by volume of the fibre-reinforced composite material.

32. The fibre-reinforced composite material according to claim 28, wherein the first polymeric composition comprises a filler in a range from 1 wt % to 10 wt % of the composite material.

33. The fibre-reinforced composite material according to claim 32, wherein the filler is a 2D material or a nanoclay.

34. The fibre-reinforced composite material according to claim 33, wherein the filler is graphene.

35. The fibre-reinforced composite material according to claim 28, wherein the fibre-reinforced composite material is a pre-preg.

36. The fibre-reinforced composite material according to claim 28, wherein the fibre-reinforced composite material is a tape, sheet or ribbon.

37. The fibre-reinforced composite material according to claim 36, wherein the fibre-reinforced composite material is a unidirectional tape, a unidirectional sheet, or a unidirectional ribbon.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0116] For a better understanding of the invention, and to show how exemplary embodiments of the same may be brought into effect, reference will be made, by way of example only, to the accompanying diagrammatic Figures, in which:

[0117] FIG. 1 schematically depicts a method according to an exemplary embodiment;

[0118] FIG. 2A schematically depicts a side elevation view of an apparatus according to an exemplary embodiment; FIG. 2B schematically depicts the apparatus, in more detail; FIG. 2C schematically depicts a side elevation view of an operating principle of the apparatus; FIG. 2D schematically depicts a side elevation view of the apparatus, in more detail; FIG. 2E schematically depicts a side elevation view of the apparatus, in use; and FIG. 2F schematically depicts a plan view of alternatives for the apparatus;

[0119] FIG. 3A is a photograph of side elevation view an apparatus according to an exemplary embodiment; FIG. 3B is a photograph of a front elevation view of the apparatus; and FIG. 3C is a photograph of a front elevation of the apparatus, in more detail;

[0120] FIG. 4A is a photograph of a glass fibre-reinforced composite material according to exemplary embodiment; and FIG. 4B is a photograph of the laminated fibre-reinforced composite material;

[0121] FIG. 5A is a photograph of a carbon fibre-reinforced composite material according to exemplary embodiment; and FIG. 5B is a photograph of the laminated fibre-reinforced composite material;

[0122] FIG. 6 schematically depicts a method of laminating a fibre-reinforced composite material according to exemplary embodiment;

[0123] FIG. 7A is a micrograph of a transverse cross-section of a fibre-reinforced composite material according to an exemplary embodiment; and FIG. 7B is a micrograph of a transverse cross-section of a conventional fibre-reinforced composite material;

[0124] FIG. 8A is a micrograph of a transverse cross-section of a fibre-reinforced composite material according to an exemplary embodiment, having a V.sub.f=70%; FIG. 8B is a micrograph of a transverse cross-section of a fibre-reinforced composite material according to an exemplary embodiment, having a V.sub.f=47%; and FIG. 8C is a micrograph of a transverse cross-section of a fibre-reinforced composite material according to an exemplary embodiment, having a V.sub.f=31%;

[0125] FIG. 9A is a graph of tensile strength of three GF/PAEK fibre-reinforced composite materials according to exemplary embodiments, having V.sub.f=70%; V.sub.f=46%; and V.sub.f=38%, respectively;

[0126] FIG. 9B is a graph of failure strain of the three GF/PAEK fibre-reinforced composite materials of FIG. 9A; and FIG. 9C is a graph of tensile modulus 0 of the three GF/PAEK fibre-reinforced composite materials of FIG. 9A;

[0127] FIG. 10A a graph of tensile strength of two conventional S2/PEEK fibre-reinforced composite materials compared with a S2/PAEK fibre-reinforced composite material according to an exemplary embodiment; and FIG. 10B is a graph of tensile modulus 0 of the two conventional S2/PEEK fibre-reinforced composite materials compared with a S2/PAEK fibre-reinforced composite material according to the exemplary embodiment of FIG. 10A;

[0128] FIG. 11 is a photograph of five fibre-reinforced composite materials according to exemplary embodiments comprising graphene at A: 0.0 wt. %; B: 0.5 wt. %; C: 1.0 wt. %; D: 2.5 wt. %; and E: 5.0 wt. %;

[0129] FIG. 12 is a graph of tensile strength of a fibre reinforced composite material according to an exemplary embodiment as a function of temperature; and

[0130] FIG. 13A is a particle size distribution for particles of a first polymeric composition for a method according to an exemplary embodiment; and FIG. 13B is a particle size distribution for particles of a first polymeric composition for a method according to an exemplary embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

[0131] FIG. 1 schematically depicts a method according to an exemplary embodiment.

[0132] At S101, the method comprises dispersing particles of a first polymeric composition comprising a first thermoplastic in a liquid comprising water, thereby forming a dispersion.

[0133] At S102, the method comprises coating, at least in part, a first set of reinforcement fibres with the dispersion.

[0134] At S103, the method comprises redistributing the particles of the first polymeric composition comprised in the coating.

[0135] At S104, the method comprises melting at least some of the redistributed particles of the first polymeric composition comprised in the coating, thereby providing the composite material.

[0136] The method may include any of the steps described with respect to the first aspect.

[0137] FIG. 2A schematically depicts a side elevation view of an apparatus 20 according to an exemplary embodiment; FIG. 2B schematically depicts a side elevation view of the apparatus in more detail.

[0138] The second aspect provides an apparatus 20 for providing a fibre-reinforced composite material M, the apparatus 20 comprising: [0139] means for coating 110, at least in part, a first set of reinforcement fibres F with a dispersion D comprising particles of a first polymeric composition comprising a first thermoplastic in a liquid comprising water; [0140] means for redistributing 120 the particles of the first polymeric composition comprised in the coating; and [0141] means for melting 130 at least some of the redistributed particles of the first polymeric composition comprised in the coating, thereby providing the composite material.

[0142] In this example, the apparatus 20 comprises a spooling device 140, for spooling the first set of reinforcement fibres F from the first spool 141.

[0143] In this example, the means for coating 110 comprises a bath 111, arranged to receive the dispersion D therein, and means for immersing the first set of reinforcement fibres F in the dispersion D.

[0144] In this example, the means for redistributing 120 the particles of the first polymeric composition comprised in the coating comprises a first set of rollers 121 including a first roller 121A (i.e. a fixed roller) for passing the coated first set of reinforcement fibres F therethrough. In this example, the first roller 121A is a drive roller, for tensioning the coated first set of reinforcement fibres F. In this example, the first set of rollers 121 includes a second roller, wherein the second roller is an idler roller. In this example, the apparatus 20 comprises means for vibrating 150 the first set of reinforcement fibres F. In this example, the means for vibrating 150 the first set of reinforcement fibres F comprises a vibrating roller, for example included in the first set of rollers 121, configured to vibrate actually and/or transversely to the axis thereof. In this example, the means for vibrating 150 the first set of reinforcement fibres F comprises a rocking arm 151. In this example, the rocking arm 151 comprises a second set of rollers 152 including a first roller 152A (i.e. a moveable roller), for example an idler roller. In this example, the rocking arm 151 comprises an actuator, configured to oscillate the rocking arm 151. In this example, the first set of rollers 121 comprises one or more fixed rollers and one or more moveable rollers (i.e. the second set of rollers 152), disposed between the one or more fixed rollers.

[0145] In this example, the apparatus 20 comprises means for laying 160 the coated first set of reinforcement fibres F. In this example, the means for laying 160 comprises a drum 161, for example a drive drum and means for steering 162 the coated first set of reinforcement fibres F on the drum. In this example, the means for steering 162 comprises an actuator arranged to axially displace the drum 161 synchronously with rotation thereof, so as to lay the coated first set of reinforcement fibres F helically on the drum.

[0146] In this example, the apparatus 20 comprises a controller configured to control a speed of conveying of the first set of reinforcement fibres F.

[0147] In this example, the means for melting 130 comprises a heater 131.

[0148] FIG. 2C schematically depicts a side elevation view of an operating principle of the apparatus 20.

[0149] While soaked in the dispersion D, the first set of reinforcement fibres F exits the bath 111 onto the fibre spreader system (i.e. the means for redistributing 120). A spreading mechanism was designed based on a direct contact method (mechanical method); use of spreading pins in which the fibre tow (i.e. the first set of reinforcement fibres F) is passed through a series of rollers to obtain a flat array of separate fibres. The fibre spreader assembly provides control over the spread of fibre (prepreg thickness) and helps impregnate the fibres with the particles. The idea here is to pass the fibre tow above and below a series of, for example ceramic or stainless steel, rollers (i.e. the first set of rollers 121) in order to push the particles inside or into the fibre tow. The forces exerted on the fibre tow by the rollers helps the dispersion D to diffuse or mutually separate the fibre filaments and therefore impregnate the fibre tow. These forces also help individual reinforcement fibres to slide on each other, spreading the fibre tow and reducing the thickness of the fibre tow. The fibre tow is also spread further by the particles in the dispersion D, which act as spacers between the individual reinforcement fibres when the dispersion D penetrates the fibre tow.

[0150] Spreading of the first set of reinforcement fibres F and/or impregnation of the dispersion D into the first set of reinforcement fibres F is further enhanced by applying a reciprocating motion on the fibre tow, held between a set of rollers. Each reciprocating motion, from step (i) to step (iv), of the fibre tow may be referred to as a tension-cycle, as shown in FIG. 2C. Increasing the number of tension-cycles enhances spreading and/or impregnation, with about six tension-cycles resulting in equilibrium in the degree of fibre spreading. Releasing the tension in the fibre tow and re-applying the tension-cycle may additionally enhance the degree of lateral spreading of the reinforcement fibres.

[0151] FIG. 2D schematically depicts a side elevation view of the apparatus 20, in more detail; and FIG. 2E schematically depicts a side elevation view of the apparatus 20, in use.

[0152] The design of the novel fibre spreader device (i.e. the means for redistributing 120) is based on the operating principle described above. The fibre spreader employs an angular reciprocating mechanism to create a vibration in a set of rollers. This device employs the operating principle described above for creating a tension-cycle, improved by automating the movement. The spreading device not only provides the reciprocating motion, but by spooling the fibre tow from spool faster than the winding unit (i.e. the means for laying 160), it maintains the fibre tow within the spreading unit in low tension and/or tension-free state. This results in greater fibre spreading. The fibre spreader includes three different parts. The first two parts (pink P and blue B) are comprised of series of DP rollers. The pink P part is static and is bolted to an aluminium profile, which is installed on the linear actuator part as discussed before. The blue part B is dynamic and is connected to the pink part P via a shafted bearing. The shaft is extended to the other end of the bearing and is connected to a spring-loaded arm. The arm is in contact with and follows, due to the spring (e), the third part of the fibre spreader (green G), which is an eccentric cam connected to a DC motor. The amplitude of the oscillation may be adjusted by moving (g) where the cam contacts the arm.

[0153] Briefly, rotation of the eccentric cam (e) causes the arm (d) to oscillate about the bearing (c). In turn, this causes oscillation of the rollers (a) and (b).

[0154] As illustrated in, the process begins when the impregnated fibre tow glides over the centring roller. As mentioned before, all the rollers except (a) and (b) are fixed on the static part of the fibre spreader assembly. Roller (a) and (b) however are mounted on a separate dynamic plate. The sequence begins when fibre tow is passed over the first roller and goes below roller (a), coming up and over two consecutive rollers, passes below roller (b) and goes over and under two more rollers. The spreading process begins when the eccentric cam (e) mounted on a DC motor starts rotating. By the means of this rotation, rod (d) starts a reciprocating motion as shown. Rod (d) is connected to the dynamic plate, which accommodates roller (a) and (b) and because of this, roller (a) and (b) start the reciprocating motion around the pivot point (c). The arm (d) and therefore the dynamic plate is restrained via spring (f). This helps arm (d) and eccentric cam (e) to always stay in contact and the process continues after each motion frequency. The reciprocating motion of roller (a) and (b) will generate the tension-cycle needed and causes the fibre tow to spread laterally on the two rollers between roller (a) and (b). Each motion frequency therefore resembles one tension-cycle described above.

[0155] Two factors in the fibre spreader assembly can be controlled; the frequency and the amplitude of the motion. The frequency of the tension-cycle can be adjusted via controlling the speed of the DC motor. The motion amplitude of roller (a) and (b) can be changed with using eccentric cams with different off-sets or adjusting the level (g) of the eccentric cam. For instance, lower levels (g) will result in higher amplitudes of roller (a) and (b).

[0156] Besides spreading the fibre tow and adjusting the thickness of the prepreg, the fibre spreading assembly is also responsible for effective PAEK powder impregnation. It is also evident that the fibre tow will spread further when polymer particles are diffused into the fibre tow and act as spacers. It is therefore believed the amount of fibre spread of dry bundle and wet bundle would be different.

[0157] FIG. 2F schematically depicts a plan view of alternatives for the apparatus 20.

[0158] The fibre spreader includes a number of DP ceramic rollers. The pink static part houses 6 rollers. The first guide is a rotating roller same as the one implemented inside the resin bath. This is a flat groove with a depth of 4 mm and width of 5 mm. This ceramic guide roller helps centring the impregnated fibre tow for the spreading stage. The static part has 4 more 10 mm diameter DP finish ceramic rollers further down the line for impregnation and fibre spread. At the end of the process is an interchangeable roller 121B that can be adjusted according to the spreading needs. Three options where envisioned: 5 mm width roller, 10 mm width roller and free roller. These guide setting options can be seen in FIG. 2F.

[0159] The blue dynamic part also accommodates two 10 mm diameter DP ceramic rollers that are responsible for creating the spreading tension-cycle mechanism. All 10 mm diameter rollers can be adjusted to be rotating or non-rotating.

[0160] FIG. 3A is a photograph of side elevation view an apparatus 30 according to an exemplary embodiment; FIG. 3B is a photograph of a front elevation view of the apparatus 30; and FIG. 3C is a photograph of a front elevation of the apparatus 30, in more detail.

[0161] The apparatus 30 is generally as described with respect to the apparatus 20, like reference signs indicate like features and description of which is not repeated for brevity.

[0162] FIG. 4A is a photograph of a fibre-reinforced composite material according to exemplary embodiment; and FIG. 4B is a photograph of the laminated fibre-reinforced composite material.

[0163] S2-glass fibre roving was supplied by AGY LLC. (USA). S2-glass fibre is a registered trademark of AGY. The grade of the S2-glass fibre roving used was 933-AA-750. The 933 version is designed for use in aerospace and defence applications. This grade consists of numerous G filament (9 microns) continuous glass strands. The strands are without mechanical twist and are treated with a thermally stable inorganic sizing suitable for high temperature matrices such as PAEKs. The 933 sizing however has poor broken filament resistance. The 933-AA-750 has a linear density of 675 g/1000 m (TEX), with 4200 filaments bundled together approximately.

Manufacturing Process

S2-Glass Fibre Tow

[0164] S2-glass is the high-end class of glass fibres and can offer up to 85% more tensile strength, while impregnated with resin, than conventional glass fibres. S2-glass fibre offers enhanced weight performance and provides better cost effective performance compared to aramid and carbon fibre. S2-glass has higher level of silica compared to standard glass fibres, which offers higher tensile and compressive strength, better toughness, and high temperature and impact resistance.

[0165] S2-glass fibre roving was supplied by AGY LLC. (USA). S2-glass fibre is a registered trademark of AGY, the sole supplier of S2 glass. The grade of the S2-glass fibre roving used was 933-AA-750. The 933 version is designed for use in aerospace and defence applications. This grade consists of numerous G filament (9 microns) continuous glass strands. The strands are without mechanical twist and are treated with a thermally stable inorganic sizing suitable for high temperature matrices such as PAEKs. 933 sizing however has poor broken filament resistance. 933-AA-750 has a linear density of 675 g/1000 m (TEX) and would approximately have 4200 filaments bundled together. Table below shows the technical data sheet of the product.

TABLE-US-00002 Properties Description or value Fibre properties Tensile strength (MPa) 4890 Tensile modulus (GPa) 89 Strain (%) 5.7 Density (g/cm.sup.3) 2.47 Filament diameter (m) 9 (G) Roving properties Yield (g/1000 m) 675 End count 10 Number of filaments 4150-4200 Sizing type/Amount (%) 933/0.23 Twist Never twisted

Polyaryl Ether Ketone (PAEK)

[0166] AE 250 PAEK (also known as engineered PAEK) is one of the most recent resin systems developed by Victrex plc. (UK). It is a PEEK based copolymer with much lower T.sub.m of 305 C. compared to PEK and T.sub.g of 149 C. It can maintain mechanical, physical and chemical properties typically to PEK, PEEK or PEKK. Properties are shown in table below.

TABLE-US-00003 Tensile Tensile Tensile Flexural Flexural Supplier/ Chemical strength modulus elongation strength modulus Grade structure (MPa) (GPa) (%) (MPa) (GPa) Victrex PAEK 90 3.5 15 150 3.3 AE 250 Glass Melt Supplier/ Melting transition viscosity Density Particle Grade point ( C.) ( C.) (Pa .Math. s) (g/cm.sup.3) size (m) Victrex 305 149 1.28 (D.sub.50) < 10 AE 250

[0167] The lower T.sub.m of AE 250 means lower processing temperature of 40 to 60 C., permitting composite parts to be manufactured cheaper and faster with added perks of implementing out of autoclave processing, fast automated lay-up, injection over-moulding and hot stamping, thus eliminating the high number use of expensive autoclaves and factories in which house them. The novel AE 250 is 25-30% semi-crystalline when press consolidated with a cooling rate of 5-10 C./min. The lower melting temperature of AE 250 resin widens the processing window whilst still allowing fully crystalline morphology to develop through the cooling phase. A major advantage of AE 250 is that it could be processed with relatively low pressures, opening gates to the production of high-quality parts utilising out of autoclave processing.

[0168] AE 250 is later found to be the most suitable resin system for manufacturing thermoplastic prepreg and is chosen as the main polymer for this research.

Liquid Carrier

[0169] Due to the low surface energy of PAEKs, they are normally not very well dispersed in water, if at all. Water alone cannot fully wet out the PAEK powder and this therefore urges the need for a dispersing agent in order to improve the separation of the particles and to prevent their settling or agglomeration in the slurry.

[0170] For this purpose, a liquid carrier from Tech Line Coatings Inc. (USA) with a tradename of LiquiPowder (L2O) was used.

[0171] L2O is a water based non-hazardous dispersion system that virtually allows any powder to be suspended in a slurry. L2O contains a blend of dispersing and water-thickening agents that promote homogenous suspension of PAEK particles in the slurry for prolonged periods without settling and helps preventing particle clumping. Resinous ingredients in L2O provide great initial bond between PAEK particles and glass fibre filaments, holding the particles firm on the fibres even after the water base is dried and evaporated. Heat melting the PAEK subsequently results in permanent bond on the reinforcing fibre. The basic powder is all that remains after curing so in effect the full characteristics are in effect for bonding. Everything in the liquid carrier leaves the composite upon melting the PAEK and only the actual resin remains.

Graphene

[0172] Graphene in nanoscale powder was supplied by Versarien plc. (UK) under the trademark of Nanene. Nanene is a high quality, low defect, few-layer and high carbon purity graphene. It has a 2D flake like structure with high lateral dimension, which can create large interfaces within the composite matrix. Below Table demonstrates the properties of Nanene.

TABLE-US-00004 Property Description or value Layers 5, 10, >10 (%) 60, 90, 10 Apparent thickness (nm) <3.5/10 layers Lateral dimension (m) <10 Bulk density (g/cm.sup.3) 0.1857 Surface area (m.sup.2/g) 45

Nanoclay

[0173] Montmorillonite nanoclay stock number NS6130-09-902 was received as powder from Nanoshel LLC. (USA) with specification as seen in Table below.

TABLE-US-00005 Property Description or value Average particle size (m) ~1 Bulk density (g/cm.sup.3) 0.7609 Density (g/cm.sup.3) 2.6 Surface area (m.sup.2/cm.sup.3) 0.09-1.8

Slurry Preparation

[0174] PAEK powder is weighted and added to weighted L2O for mixture. Ratios tested were 10% PAEK to 90% L2O by weight, 20% PAEK to 80% L2O by weight and 30% PAEK to 70% L2O. For instance, 20 grams of PAEK powder was added to 180 grams of L2O to produce 10%/90% ratio slurry. In case of adding nanomaterial, nanomaterial was added 0.5, 1, 2.5 and 5 part per hundred of PAEK by weight. For instance, 1 gram of graphene was added to 20 grams of PAEK and 180 grams of L2O in order to produce a 5% wt. graphene slurry of 10%/90% PAEK-L20 ratio.

[0175] Constituents were put in a closed mixing pot and were mixed using an overhead lab stirrer for 30 minutes at a low speed of 500 rpm followed by 30 minutes of a high speed of 1000 rpm. The slurry is then transferred into a degassing chamber where it is degassed for 1 hr under a vacuum pressure of 0.8 Pa. The slurry is slowly stirred using a magnetic stirrer while being degassed to avoid possible powder settling.

Prepreg Manufacture

[0176] First it is to ensure the surface of the drum is ready for release and is coated with release agent if required. Release agent ensures the prepreg does not stick on the drum after heating melt. While the linear actuator plate is placed far to the right or left of the actuation stoke, S2-glass tow is pulled through all the guides of the prepreg rig and is affixed on the far right or left side of the winding drum via a Kapton tape. The slurry is then added to the resin bath and the fibre spreader is turned on and set as required.

[0177] The drum starts revolution and after 2 or 3 rounds, the traverse run (linear actuator) is initiated to process the winding. The speed of the drum and the linear actuator can be adjusted accordingly.

[0178] The traverse speed vs the winding speed should regulated to accommodate slight fibre overlap when the winding process begins. This overlap is crucial due to the fact that there are minor changes in the width of fibre tow when reaching the winding drum for processing. Small overlap proves beneficial by not allowing gaps between fibre tows when the winding process initiates. The winding speed shall be selected in a way that the resin slurry does not start to run freely on the winding drum. The spreading/impregnating rollers would squeeze the excess resin off the fibre bundle, however, if very high winding speeds are selected, excess slurry cannot find enough time to drip off the rollers. It is therefore best to set the winding speed first and then adjust the linear motion in conjunction to that.

[0179] The traverse speed and the winding speed are measured in % on the controlling device. Both speeds are assigned in percentage with 0% being stop/off and 100% being full speed of the DC motors mounted on the linear actuator (Traverse) and the winding drum (Drum).

[0180] Percentage measurements needs to be converted. These percentages should be interpreted in mm/s for the traverse speed and in revolutions per minute (rpm) for winding speed (data not currently available).

[0181] After the winding is complete, the traverse motor is turned off and the impregnated fibre tow is cut off from the drum for the final stage of the process, heat melting. The drum is moved towards the end of the prepreg line, where the heating unit is located. The heating unit consists of a ceramic heater and an infrared heater. The rotating drum is firstly positioned above the ceramic heater where the wet prepreg is heated for 4 hours until all the water residues leave the prepreg, to obtain a dry prepreg. After which, the infrared heater is turned on in order to heat melt the PAEK polymer for final consolidation of polymer on the reinforcing fibre. Infrared lamps emit the heat through radiation, meaning they do not need substances like air to act as a heat convector. Infrared lamps emit shorter range wavelength than quarts or ceramic heaters, making them more ideal for heating through radiation. Temperatures on both heaters are adjusted via separate temperature controlling units.

[0182] After consolidation, the prepreg is cut from the drum. This is done by cutting the prepreg with a blade along a small groove machined across the whole length of the drum.

[0183] The laminated fibre reinforced composite material was laminated according to the method described with respect to FIG. 6.

[0184] FIG. 5A is a photograph of a fibre-reinforced composite material according to exemplary embodiment; and FIG. 5B is a photograph of the laminated fibre-reinforced composite material.

[0185] The fibre-reinforced composite material was manufactured as described above.

[0186] The laminated fibre reinforced composite material was laminated according to the method described with respect to FIG. 6.

[0187] FIG. 6 schematically depicts a method of laminating a fibre-reinforced composite material according to exemplary embodiment.

[0188] The fibre reinforced composite material is laminated by press moulding, comprising: heating whilst maintaining contact pressure; consolidating at a temperature of about 375 C. for 10 to 30 minutes at a pressure of 3 to 10 bar; and cooling while maintaining a pressure of 3 to 10 bar.

[0189] In more detail, after the prepreg material is ready and is cut from the drum, the pieces can be cut into smaller pieces. Prepreg pieces can be then stacked on each other and heat-pressed to form a composite laminate. Prepregs can be put in any stacking sequence as desired. However, for comparison purposes, all prepregs are put at 0 degree to form a unidirectional laminate. For the purpose of laminating, out-of-autoclave technique was implemented. Prepregs were cut and put into a closed mould and were heat-pressed between to platens. The processing temperature was kept constant at 350 C. Processing pressure varied from 3.5 to 14 bar. The material (mould) is heated to a temperature above the melting point of the resin and then is pressed for 10 to 30 minutes. The laminate is then cooled 5 C./min while maintaining the pressure until it reaches room temperature. After that the mould is opened and the laminate is extracted.

[0190] FIG. 7A is a micrograph of a transverse cross-section of a fibre-reinforced composite material according to an exemplary embodiment; and FIG. 7B is a micrograph of a transverse cross-section of a conventional fibre-reinforced composite material, particularly Toray Cetex TC1200 S2 PEEK (S2-Glass 204 gsm FAW UD Tape Laminate 29% RC having V.sub.f=56%), available from Toray Advanced Composites USA (Morgan Hill, CA).

[0191] The fibre-reinforced composite material was manufactured as described above.

[0192] In contrast to the conventional fibre reinforced composite material, the fibre reinforced composite material according to the exemplary embodiment exhibits full resin impregnation, very low void content, minimum resin reach area and excellent dispersion of fibres.

[0193] FIG. 8A is a micrograph of a transverse cross-section of a fibre-reinforced composite material according to an exemplary embodiment, having a V.sub.f=70%; FIG. 8B is a micrograph of a transverse cross-section of a fibre-reinforced composite material according to an exemplary embodiment, having a V.sub.f=47%; and FIG. 8C is a micrograph of a transverse cross-section of a fibre-reinforced composite material according to an exemplary embodiment, having a V.sub.f=31%.

[0194] The fibre-reinforced composite material was manufactured as described above.

[0195] Density of virtually void free and fully consolidated/laminated samples: 30% FV samples1.65 g/cm.sup.3, 47% FV1.84 g/cm.sup.3 and 70% FV2.13 g/cm.sup.3.

TABLE-US-00006 TABLE 2 Densities of fibre reinforced composite materials Fibre reinforced composite PAEK in dispersion material Density wt. % V.sub.f g/cm.sup.3 10 70 2.13 20 46 1.84 30 38 1.65

[0196] FIG. 9A is a graph of tensile strength of three GF/PAEK fibre-reinforced composite materials according to exemplary embodiments, having V.sub.f=70%; V.sub.f=46%; and V.sub.f=38%, respectively; FIG. 9B is a graph of failure strain of the three GF/PAEK fibre-reinforced composite materials of FIG. 9A; and FIG. 9C is a graph of tensile modulus 0 of the three GF/PAEK fibre-reinforced composite materials of FIG. 9A.

[0197] The fibre-reinforced composite material was manufactured as described above.

TABLE-US-00007 TABLE 3 Tensile strength, failure strain and tensile modulus 0 Fibre reinforced Tensile PAEK in composite Tensile Failure modulus dispersion material strength strain 0 wt. % V.sub.f MPa % GPa 10 70 1760 2.8 67 20 46 1350 3.2 47 30 38 900 3.8 31

[0198] FIG. 10A a graph of tensile strength of two conventional S2/PEEK fibre-reinforced composite materials, specifically Cytec APC-2 S-2 glass fiber reinforced unidirectional tape (product code APC-2/S-2 glass, available from Cytec Solvay Group, Heanor, UK) and Toray Cetex TC1200 S2 PEEK, compared with a S2/PAEK fibre-reinforced composite material according to an exemplary embodiment; and FIG. 10B is a graph of tensile modulus 0 of the two conventional S2/PEEK fibre-reinforced composite materials compared with a S2/PAEK fibre-reinforced composite material according to the exemplary embodiment of FIG. 10A. Cytec APC-2 and Cetex TC1200 S2 PEEK are prepregs, like the S2/PAEK fibre-reinforced composite material according to the exemplary embodiment.

[0199] The fibre-reinforced composite material was manufactured as described above.

[0200] The tensile strength and the tensile modulus 0 of the S2/PAEK fibre-reinforced composite material according to the exemplary embodiment have been normalised to account for the differences in mechanical properties between PEEK and PAEK and the V.sub.f of the S2/PAEK fibre-reinforced composite material.

TABLE-US-00008 TABLE 4 Tensile strength and tensile modulus 0. Fibre reinforced Tensile Tensile composite strength modulus 0 material MPa GPa Cytec APC-2 1170 55 S2 PEEK Toray Cetex TC1200 1520 52 S2 PEEK S2/PAEK fibre-reinforced 1580 60 composite material (normalised (normalised according to the exemplary from 1760) from 66.8) embodiment

[0201] The tensile strength of the fibre reinforced composite material according to an exemplary embodiment is 35% greater than for APC-2 and 4% greater than for Cetex TC1200. The tensile modulus 0 of the fibre reinforced composite material according to the exemplary embodiment is 9% greater than for APC-2 and 15% greater than for Cetex TC1200. That is, these mechanical properties of the fibre reinforced composite material according to the exemplary embodiment are significantly improved compared with the conventional fibre reinforced composite materials.

[0202] FIG. 11 is a photograph of five fibre-reinforced composite materials according to exemplary embodiments comprising graphene at A: 0.0 wt. %; B: 0.5 wt. %; C: 1.0 wt. %; D: 2.5 wt. %; and E: 5.0 wt. %. wt. % with respect to the particles i.e. the PAEK.

[0203] The fibre-reinforced composite material was manufactured as described above.

[0204] FIG. 12 is a graph of ultimate tensile strength (UTS) of a fibre reinforced composite material according to an exemplary embodiment as a function of temperature.

[0205] The fibre-reinforced composite material was manufactured as described above.

[0206] The tensile strengths (UTS) of tensile test specimens of the fibre reinforced composite material, particularly 10% PAEK laminates (70% fibre volume), were tested at five temperatures between room temperature and 250 C., as detailed in Table 3.

TABLE-US-00009 TABLE 5 UTS as a function of temperature Temperature UTS Reduction in C. MPa tensile strength % Room temperature 1760 0 100 1630 7 150 1590 10 200 1530 13 250 1480 16

[0207] While the tensile strength reduced linearly as a function of temperature, the reduction in tensile strength is significantly less than observed for conventional fibre reinforced composite materials. FIG. 13A is a particle size distribution for particles P1, specifically Victrex PEEK AE250 Grade 20, of a first polymeric composition for a method according to an exemplary embodiment; and FIG. 13B is a particle size distribution for particles P2, specifically Victrex PEEK AE250 Grade of a first polymeric composition for a method according to an exemplary embodiment. Table 6 summarises the particle size distributions for these particles P1 and P2, together with other examples P3 to P7. Particle size distributions were measured using a Malvern Instruments Ltd. Mastersizer 2000, operated according to the manufacturer's instructions, and processed using Mastersizer 2000 Ver. 5.60 software. Particles P1 and, to a lesser extent, particles P2 have a trimodal distribution, including a portion (about 3.5% by volume) of relatively smaller particles (up to 3 m) and a portion (about 5% by volume) of relatively larger particles (at least 30 m). Generally, D10 is about 5 m, D50 is about 10 m and D90 is about 20 m.

TABLE-US-00010 TABLE 6 D10, D20, D50 and D90 for particles P1 to P7 D10 D20 D50 D90 Particles m m m m P1 4.437 5.728 9.253 21.545 P2 5.462 6.689 10.064 20.449 P3 4.904 6.146 9.547 19.819 P4 5.045 6.351 9.977 21.458 P5 5.056 6.376 10.045 21.941 P6 4.968 6.246 9.762 20.735 P7 4.396 5.771 9.491 22.340

ALTERNATIVES

[0208] Although a preferred embodiment has been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims and as described above.

SUMMARY

[0209] In summary, the invention provides a design and manufacture of a novel drum winding thermoplastic prepreg rig capable of manufacturing unidirectional thermoplastic prepreg using an aqueous dispersion of thermoplastic powder in a laboratory scale production.

REFERENCES

[0210] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0211] All of the features disclosed in this specification (including any accompanying claims and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at most some of such features and/or steps are mutually exclusive.

[0212] Each feature disclosed in this specification (including any accompanying claims, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0213] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.