Thermoplastic composite
A method of making a flexible pipe layer, which method comprises: commingling polymer filaments and carbon fibre filaments to form an intimate mixture, forming yarns of the commingled filaments, forming the yarns into a tape, and applying the tape to a pipe body to form a flexible pipe layer.
1. A thermoplastic composite comprising fluoropolymer filaments and carbon fibre filaments, wherein the fluoropolymer filaments and carbon fibre filaments are commingled to form an intimate mixture, and wherein the fluoropolymer has a melt flow index (230° C./2.16 kg) in the range of 50 to 80 g/10 min, wherein the carbon fibre filaments have a tow size of 3000 to 12000.
2. A composite according to claim 1 , wherein the fluoropolymer has a melt flow index (230° C./2.16 kg) in the range of 60 to 70 g/10 min.
3. A composite according to claim 1 , wherein the fluoropolymer is selected from at least one of perfluoroalkoxy alkanes (PFA), poly(ethene-co-tetrafluoroethene) (ETFE), polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP) and polyvinylidene fluoride (PVDF).
4. A composite according to claim 1 , wherein the fluoropolymer is polyvinylidene fluoride (PVDF).
5. A composite according to claim 1 , wherein the fluoropolymer is present in an amount of 30 to 70 weight % of the total weight of the fluoropolymer and carbon fibre.
6. A composite according to claim 1 , which is in the form of a yarn.
7. A composite according to claim 6 , wherein the composite is a tape formed from a plurality of yarns.
8. A composite according to claim 7 , wherein the tape comprises a first region formed from a plurality of yarns having a first concentration of carbon fibre, and a second region formed from a plurality of yarns having a second concentration of carbon fibre, wherein the first and second concentrations are different.
9. A composite according to claim 7 , wherein the tape comprises a region formed from a plurality of yarns, and a different region formed from a plurality of yarns consisting essentially of the fluoropolymer filaments.
10. A flexible pipe comprising at least one pipe layer formed from a tape of a composite according to claim 1 .
11. A pipe as claimed in claim 10 , wherein the at least one pipe layer formed from a tape of the composite is a pressure armour layer, which is positioned adjacent to a tubular polymer layer.
12. A pipe according to claim 11 , wherein the tubular polymer layer is formed on the inside of the pressure armour layer as a fluid barrier layer.
13. A pipe according to claim 10 , wherein the pipe layer is obtainable by wrapping the tape around a pipe body to form a pipe layer, and heating the tape so that the fluoropolymer filaments melt around the carbon filaments to form a fluoropolymer matrix.
14. A method of making a thermoplastic composite according to claim 1 , wherein the method comprises commingling fluoropolymer filaments and carbon fibre filaments to form an intimate mixture.
15. A method according to claim 14 , wherein the filaments are commingled using a compressed gas or a series of combs to form the intimate mixture of the filaments.
16. A method according to claim 14 , wherein the method comprises forming yarns of the commingled filaments, and compressing or extruding the yarns to form a tape of the thermoplastic composite.
17. A method according to claim 16 , wherein the method comprises:
arranging a first region of yarns having a first concentration of carbon fibre adjacent to a second region of yarns having a second concentration of carbon fibre, and
compressing or extruding the yarns to form a tape, whereby the tape has a first region having a first concentration of carbon fibre, and a second region having a second concentration of carbon fibre.
18. A method according to claim 16 , wherein the method comprises arranging a first region of yarns that contain carbon fibre adjacent to a second region of yarns consisting essentially of fluoropolymer, and
compressing or extruding the yarns to form a tape, whereby the tape has a first region containing carbon fibre, and a second region consisting essentially of fluoropolymer.
19. A method as claimed according to claim 16 , wherein the method comprises wrapping the tape around a pipe body, and heating the wrapped tape so that the fluoropolymer filaments melt around the carbon filaments to form a fluoropolymer matrix.
20. A method according to claim 19 , wherein the pipe body comprises an extruded tubular polymer layer.