Polymeric materials

Abstract

A component comprising a first part and a second part, wherein a third part is positioned between the first and second parts, wherein: (iv) said first part comprises a polymeric material (A) which comprises a repeat unit of formula (XI) ##STR00001## wherein t1, and w1 independently represent 0 or 1 and v1 represents 0, 1 or 2; (v) said second part comprises a polymeric material (B) which comprises a repeat unit of formula (XI) ##STR00002## wherein t1, and w1 independently represent 0 or 1 and v1 represents 0, 1 or 2; and (vi) said third part comprises a polymeric material (C) which comprises a polymer having a repeat unit of formula
O-Ph-O-Ph-CO-Ph-I and a repeat unit of formula
O-Ph-Ph-O-Ph-CO-Ph-II wherein Ph represents a phenylene moiety.

Claims

1. A component comprising a first part and a second part, wherein a third part having a different composition than the first and second parts is positioned between the first and second parts, wherein: (i) said first part comprises a polymeric material (A) selected from the group consisting of PEEK, PEK, PEKEKK, and PEKK; (ii) said second part comprises a polymeric material (B) selected from the group consisting of PEEK, PEK, PEKEKK, and PEKK; and (iii) said third part comprises a polymeric material (C) which comprises a polymer having a repeat unit of formula
O-Ph-O-Ph-CO-Ph-I and a repeat unit of formula
O-Ph-Ph-O-Ph-CO-Ph-II wherein Ph represents a phenylene moiety.

2. The component according to claim 1, wherein the level of crystallinity in said polymeric material (A) is at least 15%, and the level of crystallinity in said polymeric material (B) is at least 15%; and/or wherein in said polymeric material (C), the following relationship applied:
log 10(X%)>1.500.26 MV; wherein X % refers to the % crystallinity measured as described in Example 2 and MV refers to the melt viscosity; and/or wherein said polymeric material (C) has a crystallinity of at least 25%.

3. The component according to claim 1, wherein said polymeric material (A) has a melt viscosity (MV) of at least 0.06 kNsm.sup.2 wherein MV is measured using capillary rheometry operating at 400 C. at a shear rate of 1000 s.sup.1 using a circular cross-section tungsten carbide die, 0.5 mm (capillary diameter)3.175 mm (capillary length) and/or said polymeric material (B) has a MV of at least 0.06 kNsm.sup.2.

4. The component according to claim 1, wherein said polymeric material (A) is part of a first composition which includes polymeric material (A) and a filler means; and/or wherein said first composition includes 20 to 99.9 wt % of polymeric material (A) and 0.1 to 80 wt % of filler means; and/or wherein said first composition includes 40 to 60 wt % of carbon fibres and 40 to 60 wt % of polymeric material (A).

5. The component according to claim 1, wherein said polymeric material (B) is part of a second composition which includes polymeric material (B) and a filler means; and/or wherein said second composition includes 20 to 99.9 wt % of polymeric material (B) and 0.1 to 80 wt % of filler means; and/or wherein said second composition includes 40 to 60 wt % of carbon fibres and 40 to 60 wt % of polymeric material (B).

6. The component according to claim 1, wherein, in said first part and said second part, said polymeric materials (A) and (B) are the same and/or wherein said first and second parts have substantially the same composition.

7. The component according to claim 1, wherein said repeat units I and II are in the relative molar proportions 1:11 of from 65:35 to 95:5.

8. The component according to claim 1, wherein the Tm of said polymeric material (C) is less than 330 C. and is greater than 280 C.; and/or wherein the difference between the melting temperature Tm of said polymeric material (A) and said polymeric material (C) is at least 20 C.

9. The component according to claim 1, wherein said third part include at least 50 wt % of said polymeric material (C).

10. The component according to claim 1, wherein the area of the first part which is superimposed upon the second part is at least 10 cm.sup.2, or a thickness of the first part measured perpendicular to the interface between the first and second parts is at least 2 mm.

11. The component according to claim 1, wherein said third part has a thickness no greater than 100 m.

12. The component according to claim 1, wherein said third part defines a substantially continuous layer positioned between the first and second parts.

13. The component according to claim 1, wherein said component comprises said first part which defines a first layer; said third part which defines a second layer in contact with the first layer; said second part which defines a third layer in contact with the second layer; a fourth layer in contact with the third layer which includes said polymeric material (C); and a fifth layer in contact with the fourth layer which includes polymeric material (A).

14. The component according to claim 1, wherein the first and third parts are formed as co-extruded tape.

15. The component according to claim 1, wherein the second part includes voids and has a honeycomb structure.

16. A method of making a component, the method comprising: arranging a polymeric material (C) between a first member comprising a polymeric material (A) and a second member comprising a polymeric material (B), wherein said first member comprises a polymeric material (A) as described in claim 1; said second member comprises a polymeric material (B) as described in claim 1; and said polymeric material (C) is as described in claim 1.

17. The method according to claim 16, wherein the method comprises subjecting polymeric material (C) to a temperature which is less than the melting temperature, Tm, of the polymeric material (A) in said first member and less than the Tm of the polymeric material (B) in said second member but is greater than the Tm of said polymeric material (C); and/or, wherein said temperature is less than 330 C.; and is greater than 280 C.

18. The method according to claim 16, wherein said polymeric material (C) is in the form of a film; and/or, in the method, cooling of the polymeric material (C) after melting is controlled so polymeric material (C) develops crystallinity.

Description

(1) Specific embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

(2) FIG. 1 which is a schematic representation of two parts prior to being bonded together using a first method;

(3) FIG. 2 is a schematic representation of two parts being bonded together using a second method;

(4) FIG. 3 is a schematic cross-section of co-extruded tapes woven together;

(5) FIG. 4 is a schematic representation of three layers of the woven tapes of FIG. 3 being combined to form a structure;

(6) FIG. 5 is a schematic representation of a laminar structure including a honeycomb layer, prior to assembly; and

(7) FIG. 6 is a schematic representation of the laminar structure of FIG. 5 after assembly.

(8) The following materials are referred to hereinafter:

(9) Polymer composition APEEK 90Gpolyetheretherketone (PEEK) having a melt viscosity (MV) of 0.09 KNsm.sup.2 (measured as described herein) obtained from Victrex Manufacturing Ltd.

(10) Polymer composition BPEEK-PEDEKa copolymer made as described in Example 1 having an MV of 0.15 KNsm.sup.2 (measured as described herein), a Tg of 149 C., a Tm of 302 C. and a crystallinity of 29%, measured as described in Example 2.

(11) Polymer composition Crefers to PEEK having a melt viscosity of 0.09 KNsm.sup.2 with 40 wt % high modulus short carbon fibres, sold as Victrex 90HMF40 by Victrex Manufacturing Ltd.

(12) Polymer composition Drefers to PEEK having a melt viscosity of 0.09 KNsm.sup.2 with 30 wt % glass fibres, sold as Victrex 90GL30 by Victrex Manufacturing Ltd.

(13) Polymer composition Erefers to PEEK having a melt viscosity of 0.09 KNsm.sup.2 with 30 wt % aramid fibre.

(14) Polymer composition Frefers to PEEK having a melt viscosity of 0.09 KNsm.sup.2 with 30 wt % ceramic.

(15) Ceramicrefers to Deranox 970 Alumina obtained from Morgan Technical Ceramics.

(16) Aramid fibrerefers to DuPont Kevlar 49 woven fabric.

(17) Epoxyrefers to Araldite (Trade Mark) AV138M/HV998.

(18) Skydrol PE-5hydraulic aviation fluid obtained from Eastman Chemical Company.

(19) The copolymer used in polymer composition B was made as follows:

EXAMPLE 1PREPARATION OF POLYETHERETHERKETONE (PEEK)-POLYETHERDIPHENYLETHERKETONE (PEDEK) COPOLYMER

(20) A 300 litre vessel fitted with a lid, stirrer/stirrer guide, nitrogen inlet and outlet was charged with diphenylsulphone (125.52 kg) and heated to 150 C. Once fully melted 4,4-diflurobenzophenone (44.82 kg, 205.4 mol), 1,4-dihydroxybenzene (16.518 kg, 150 mol) and 4,4-dihydroxydiphenyl (9.311 kg, 50 mol) were charged to the vessel. The contents were then heated to 160 C. While maintaining a nitrogen blanket, dried sodium carbonate (21.368 kg, 201.6 mol) and potassium carbonate (1.106 kg, 8 mol), both sieved through a screen with a mesh of 500 micrometres, were added. The D50 of the sodium carbonate was 98.7 m. The temperature was raised to 180 C. at 1 C./min and held for 100 minutes. The temperature was raised to 200 C. at 1 C./min and held for 20 minutes. The temperature was raised to 305 C. at 1 C./min and held until desired melt viscosity was reached, as determined by the torque rise of the stirrer. The required torque rise was determined from a calibration graph of torque rise versus MV. The reaction mixture was poured via a band caster into a water bath, allowed to cool, milled and washed with acetone and water. The resulting polymer powder was dried in a tumble dryer until the contents temperature measured 112 C. The copolymer had a crystallinity of 29%, measured as described in Example 2.

EXAMPLE 2DIFFERENTIAL SCANNING CALORIMETRY TO ASSESS CRYSTALLINITY

(21) Crystallinity referred to herein may be assessed by several methods for example by density, by it spectroscopy, by X-ray diffraction or by differential scanning calorimetry (DSC). The DSC method has been used to evaluate the crystallinity of polymers described herein using a Mettler Toledo DSC1 Star system with FRS5 sensor.

(22) The Glass Transition Temperature (Tg), the Melting Temperature (Tm) and Heat of Fusions of Melting (Hm) for the polymers described herein may be determined using the following DSC method.

(23) A 8 mg sample of the polymer was heated from 30 C. to 400 C. at 20 C./min, held for 5 minutes, then cooled at 20 C./minute to 30 C. and held for 5 minutes at this temperature. The heat/cool cycle was repeated. From the DSC trace obtained from the second heat/cool cycle, the onset Tg was obtained as the intersection of the lines drawn along the pre-transition baseline and a line drawn along the greatest slope obtained during the transition. The Tm was the temperature at which the main peak of the melting endotherm reached a maximum.

(24) The Heat of Fusion for melting (Hm) was obtained by connecting the two points at which the melting endotherm deviates from the relatively straight baseline. The integrated area under the endotherm as a function of time yields the enthalpy (mJ) of the melting transition: the mass normalised heat of fusion is calculated by dividing the enthalpy by the mass of the specimen (J/g). The level of crystallisation (%) is determined by dividing the Heat of Fusion of the specimen by the Heat of Fusion of a totally crystalline polymer, which for polyetheretherketone is 130 J/g.

(25) Using DSC as described, the copolymer of Example 1 had the following characteristics: Tg=149 C., Tm=302 C.

EXAMPLE 3GENERAL PROCEDURE FOR TESTING OF SAMPLES

(26) Parts were machined into 25 mm wide strips, giving a 25 mm25 mm overlap bonded area. Single lap-joint shear tests were carried out on an Instron tensile testing machine operating with a 50KN load cell and a cross-head speed of 13 mm/min in accordance with ASTM-5858. Measurements were carried out at 23 C. and 120 C. The maximum load was recorded giving an indication of the bond strength.

EXAMPLE 4GENERAL PROCEDURE FOR MAKING PARTS (FIRST METHOD)

(27) Polymer composition C was provided as a part in the form of a pre-preg plate which was made by coating a carbon fibre mat with finely powdered PEEK having melt viscosity as described. The PEEK is subsequently melted so it penetrates throughout the mat. The mat was cut to define a 160 mm250 mm plate.

(28) A pre-preg plate comprising Polymer composition E was prepared as for composition C except using an aramid fibre mat.

EXAMPLE 5GENERAL PROCEDURE FOR MAKING PARTS (SECOND METHOD)

(29) Parts made from Polymer composition A were obtained from injection moulded plaques which were made using an Engel 740/220 injection moulding machine with a tool temperature of 145-155 C., barrel temperature of 350 C.-360 C., nozzle temperature 365 C., holding pressure of 30 bar, injection pressure of 140 bar and screw speed of 45 rpm. The plaques were then machined to the required size (160 mm250 mm). Parts made from Polymer compositions D and F were obtained in the same way except that the tool temperature was increased to 180-200 C., the barrel temperature was increased to 370-380 C. and the nozzle temperature was increased to 380 C.

(30) A summary of the parts made is provided in Table 1.

(31) TABLE-US-00001 TABLE 1 Part Reference Polymer Composition Summary P1 A Made as described in Example 5 P2 D Made as described in Example 5 P3 C Made as described in Example 4 P4 E Made as described in Example 4 P5 F Made as described in Example 5

EXAMPLE 6GENERAL PROCEDURE FOR BONDING COMPONENTS TO ONE ANOTHER USING POLYMER COMPOSITION B (FIRST METHOD)

(32) A 15 m thick piece of film made from a selected polymer composition was co-consolidated with a first part in an injection moulding compression tool to define a first assembly 2 comprising the first part 4 and film 6, as represented in FIG. 1. Co-consolidation involves placing the film (160 mm250 mm) in a compression moulding tool which had previously been treated with release agent. Then an injection moulded plaque (160 mm250 mm) made as described in Example 5 was placed on top of the film in the tool, the tool was heated to 320 C. and held at this temperature and a pressure of 50 bar for 10 minutes before being cooled to 60 C., whereupon the consolidated part was removed. A second assembly 8 comprising a second part 10 and a film 12 is produced in a similar manner.

(33) The bonding surfaces of the assemblies 2, 8 to be joined were cleaned by wiping with acetone to remove grease and dirt and allowed to dry. The assemblies were bonded together in a single overlap shear geometry. This involved the assemblies being brought together in a press with a 25 mm overlap. Spacers were used to keep the composite plates parallel to each other whilst pressure was applied. The platens of the press were heated up from 60 C. to 320 C. over 30 minutes, held at 320 C. for 20 minutes and then cooled down to 60 C. over 40 minutes whilst under a pressure of 50 Ncm.sup.2 which was held over the 90 minute duration.

EXAMPLE 7GENERAL PROCEDURE FOR BONDING COMPONENTS TOGETHER USING POLYMER COMPOSITION B (SECOND METHOD)

(34) As an alternative to the method of Example 6, the two step process (i.e. produce co-consolidated first and second parts; and then bond the first and second parts) was replaced with a one step process represented in FIG. 2 wherein first and second parts 20, 22 are bonded together by a single piece of film 24. In this case, as shown in FIG. 2, composite plates defining parts 20, 22 were placed in a press with a 25 mm overlap and with a 25 m film 24 in-between.

(35) Spacers were used as described in Example 6 and the plates of the press were heated up from 60 C. to 320 C. over 30 minutes, held at 320 C. for 20 minutes and then cooled down to 60 C. over 40 minutes whilst under a pressure of 50 Ncm.sup.2 which was held over 90 minutes duration.

EXAMPLE 8GENERAL PROCEDURE FOR BONDING COMPONENTS TOGETHER USING COMPOSITION B (THIRD METHOD)

(36) As an alternative to Examples 6 and 7, one part (e.g. part 2 of FIG. 1) may be bonded to a part (e.g. part 20 of FIG. 2) using a film 24 in a press, generally using the conditions described in Examples 6 and 7.

EXAMPLE 9GENERAL PROCEDURE FOR BONDING COMPONENTS TOGETHER USING POLYMER COMPOSITION B (FOURTH METHOD)

(37) In a further alternative, one part (e.g. part 2 of FIG. 1|) may be bonded to a part (e.g. part 20 of FIG. 2) via film 6 which is a component of part 2; that is, only a single layer of film may be used.

EXAMPLE 10 (COMPARATIVE)GENERAL PROCEDURE FOR BONDING COMPONENTS TOGETHER USING POLYMER COMPOSITION A

(38) The procedure described in Examples 6 and 7 was generally followed except that films 6, 12, 24 comprised Polymer Composition A. Polymer composition A melts at a higher temperature than Polymer Composition B. Accordingly, the process differs from that described in Example 4, 6 and 7 in that the assemblies are heated at 340 C. after being brought together, to thereby bond the assemblies together.

EXAMPLE 11 (COMPARATIVE)GENERAL PROCEDURE FOR BONDING COMPOSITIONS TOGETHER USING EPOXY

(39) First and second parts to be bonded together are cleaned as described in Example 6 and then the two component Epoxy adhesive is applied directly to the parts and a 15 minute 100 C. curing cycle was used to bond the parts together.

(40) Results

(41) The strength of the bonds between parts of the assemblies made as described in Examples 4 to 6 was assessed using the test described in Example 3 and the results are provided in Table 2.

(42) TABLE-US-00002 TABLE 2 MAXIMUM LOAD (Nmm2) Adhesive used to bond parts PARTS BONDED METHOD Epoxy as TOGETHER USED TO Film(s) of Polymer Film(s) of Polymer described in Part 1 Part 2 BOND Composition B Composition A Example 11 reference reference PARTS 23 C. 120 C. 23 C. 120 C. 23 C. 120 C. P1 P2 Example 6 20.0 17.7 19.8 17.3 5.1* 2.9.sup.# P1 P3 Example 6 21.2 19.0 20.0 17.6 5.5* 3.4.sup.# P3 P3 Example 7 19.5 17.5 19.3 17.0 5.5* 3.1.sup.# P3 P4 Example 6 19.2 17.8 19.3 17.6 5.0* 3.0.sup.# P3 P5 Example 6 20.0 18.2 19.8 18.0 4.8* 2.5.sup.# The following notes apply to Table 2: *exhibits adhesive failure at adhesive/substrate interface .sup.#exhibits cohesive failure of the adhesive leaving adhesive on both sides of the substrate.

(43) Referring to Table 2, the following should be noted: (i) The use of Polymer Composition B (PEEK-PEDEK) results in a stronger bond between bonded parts compared to use of Polymer Composition A (PEEK). In addition, since Polymer Composition B needs only to be heated to, for example 305 C., the PEEK included in parts P1 to P5 will not be melted in the bonding process thereby obviating distortion of and introduction of stress into parts P1 to P5 during the process. (ii) The use of Polymer Composition B results in a stronger bond between bonded parts compared to the use of epoxy resin for which cohesive failure at low loads was observed at 23 C. At higher temperatures (120 C.), the fall-off in bond strength is very significant meaning that epoxy use in challenging (e.g. aerospace) applications is impractical.

(44) The chemical resistance of parts tested was assessed as described in Example 12.

EXAMPLE 12CHEMICAL RESISTANCE OF PARTS

(45) Parts made from pre-preg plates of composition C bonded with either epoxy or composition B were immersed in hydraulic aviation fluid (Skydrol PE-5) at room temperature for a period of 24 hours. The strips were then dried under vacuum at 70 C. for 24 hours. Visual inspection of the bond of the epoxy bonded part indicated some dissolution of the bonding material at the periphery of the bond, whereas the sample bonded with composition B appeared to be unaffected. Lap shear tests carried out on the parts gave a value of 19.2 Nmm.sup.2 for the part bonded with composition B, which was found to be comparable to a part not immersed in aviation fluid. No comparative value could be obtained from the epoxy bonded part owing to the deterioration of the bond. This illustrates the superior chemical resistance of composition B over the epoxy material.

(46) A layer of Polymer composition B may be used as an adhesive to secure two parts which comprise PEEK (or another polyaryletherketone) together. For example, Composition B may be used to secure parts together in aircraft manufacture. For example, the following aircraft parts may be secured: internal fuselage panels, internal flooring panels, ribs and beams within aircraft wings and wing structures and aircraft control structures such as ailerons, flaps and rudders.

(47) In one embodiment, Polymer composition B may be used as an adhesive as illustrated in FIGS. 3 and 4. A woven layer 30 comprises elongate warp tapes 32 (typically of 10-100 m), each comprising a layer 34 comprising PEEK and a juxtaposed layer 36 comprising Polymer composition B. The layer 30 also includes weft tapes 40 (typically of 10-100 m), which are the same as the warp tapes. The warp and weft tapes are woven into carbon fabric 43.

(48) A structure illustrated in FIG. 4 comprises three woven layers 30a, 30b and 30c (each being as described with reference to FIG. 3) which are assembled in a stack and then subjected to heat (to melt the Polymer composition B in the layers 30a, 30b and 30c but not to melt the PEEK within the layers) and pressure (in the direction of arrows 50, 52) to urge the layers together. Polymer composition B acts as an adhesive to secure the PEEK layers together, since in the consolidated structure, polymer Composition B penetrates the carbon fabric.

(49) Each tape 32, 40 may be made by co-extrusion followed by stretching to orient it and increase the tensile strength of the PEEK layer to above 500 MPa (when measured in accordance with ASTMD3759). The stretched tapes may then be woven as described. Alternatively, lengths of oriented PEEK tape and non-oriented tape comprising Polymer B composition may be selected and superimposed to define a pair of tapes which is co-weaved with another identical pair of tapes to define the structure in FIG. 3.

(50) In a second embodiment, Polymer composition B may be used as an adhesive in the manufacture of honeycomb based structures. FIG. 5 shows a light-weight honeycomb core 50 made from PEEK. In an alternative embodiment the light-weight honeycomb core 50 may be made from the Polymer composition B. On opposite sides of the core 50 are shown composite structures 52 each of which comprises a composite skin 54 made from PEEK and carbon fibre and a film layer 56 made from Polymer composition B. The components shown in FIG. 5 may be pressed together and heated through the skins 54 to melt the film layers 56 so that the core 50 fuses to the composite structures 52, to define a structure as shown in FIG. 6.

(51) 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, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.