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US-12617161-B2 - Hybrid veil as interlayer in composite materials

US12617161B2US 12617161 B2US12617161 B2US 12617161B2US-12617161-B2

Abstract

A flexible, self-supporting hybrid veil that is permeable to liquid and gas. The hybrid veil includes: (a) intermingled, randomly arranged fibres in the form of a nonwoven structure; (b) particles dispersed throughout the nonwoven structure, wherein a majority of the particles are penetrating through the thickness of the nonwoven structure; and (c) a polymeric or resinous binder present throughout the veil. Such hybrid veil can be incorporated into composite laminates, prepregs, fabrics and fibrous preforms.

Inventors

  • Carmelo Luca Restuccia
  • Robert Blackburn

Assignees

  • CYTEC INDUSTRIES INC.

Dates

Publication Date
20260505
Application Date
20220308

Claims (17)

  1. 1 . A hybrid veil that is flexible, self-supporting, and is permeable to liquid and gas, comprising: (a) intermingled, randomly arranged carbon fibres in the form of a nonwoven structure; (b) polymeric particles dispersed throughout the nonwoven structure, wherein a majority of the polymeric particles are penetrating through the thickness of the nonwoven structure; and (c) a polymeric or resinous binder present throughout the veil, wherein each of the polymeric particles consists of one or more thermoplastic polymers, or one or more elastomeric polymers, or crosslinked thermoplastic polymers, and wherein the binder is present in an amount of 5% to 25% by weight, based on the total weight of the veil.
  2. 2 . The hybrid veil of claim 1 , wherein the hybrid veil has an areal weight of less than or equal to 12 gsm.
  3. 3 . The hybrid veil of claim 2 , wherein the hybrid veil has an areal weight of 5 gsm to 12 gsm.
  4. 4 . The hybrid veil of claim 1 , wherein weight ratio of carbon fibres to polymeric particles in the veil is within the range of 5:1 to 1:1.
  5. 5 . The hybrid veil of claim 1 , wherein the binder is present in an amount of 10% to 20% by weight, based on the total weight of the veil.
  6. 6 . The hybrid veil of claim 1 , wherein the carbon fibres of the nonwoven structure are chopped fibres having lengths in the range of about 3 mm to about 18 mm.
  7. 7 . The hybrid veil of claim 1 , wherein the carbon fibres of the nonwoven structure have cross-sectional diameters in the range of about 3.0 μm to about 15 μm.
  8. 8 . The hybrid veil of claim 1 , wherein each of the polymeric particles consists of are polyamide or polyimide particles.
  9. 9 . The hybrid veil of claim 1 , wherein the particles have a particle size distribution d50 in the range of about 10 μm to about 50 μm, as measured by laser diffraction.
  10. 10 . The hybrid veil of claim 1 , wherein the polymeric or resinous binder comprises a component selected from: thermoplastic polymers, elastomeric polymers, thermosetting resins, copolymers thereof and combinations thereof.
  11. 11 . The hybrid veil according to claim 10 , wherein the binder comprises a component selected from: vinyls, including poly vinyl alcohol (PVA), poly ethylene vinyl alcohol (PEVOH), poly vinyl acetate, poly vinyl ether, poly vinyl chloride (PVC) and poly vinyl ester; butadienes; silicones; polyesters; polyamides; cross-linked polyesters; acrylics; epoxies; phenoxies; phenolics; polyurethanes; phenol-formaldehyde resin; urea-formaldehyde resin; copolymers thereof and combinations thereof.
  12. 12 . A composite laminate comprising: a layup of prepreg plies arranged in a stacking arrangement, each prepreg ply comprising a layer of reinforcement fibres that has been impregnated with a curable matrix resin; and the hybrid veil of claim 1 interleaved between two adjacent prepreg plies.
  13. 13 . A fibrous preform configured for liquid resin infusion, comprising: a plurality of fibrous layers that are permeable to liquid resin; and the hybrid veil of claim 1 interleaved between two adjacent fibrous layers.
  14. 14 . The fibrous preform of claim 13 , wherein the fibrous layers are selected from: woven and nonwoven fabrics, and multi-axial fabrics.
  15. 15 . A prepreg comprising: reinforcement fibres impregnated with a curable resin; and the hybrid veil of claim 1 embedded in the same curable resin.
  16. 16 . The prepreg of claim 15 , wherein the reinforcement fibres are unidirectional carbon fibres.
  17. 17 . A fabric that can be infused with a liquid resin, comprising: at least one fabric ply comprising unidirectional fibers; and the hybrid veil of claim 1 attached to the fabric ply.

Description

The present application is a continuation of U.S. application Ser. No. 15/771,532, filed on 27 Apr. 2018, which is a U.S. national phase entry under 35 U.S.C. § 371 of International Application No. PCT/US2016/061506, filed on 11 Nov. 2016, which claims priority to U.S. provisional Application No. 62/254,224, filed on 12 Nov. 2015, the entire content of each of these prior filed applications is incorporated herein by reference. The use of fibre-reinforced polymer composites is becoming more prevalent in primary aerospace structures, e.g., fuselage of airplane, as well as in high-performance sporting goods, marine and wind energy structures. The advantages of fibre-reinforced polymer composites include high strength-to-weight ratio, excellent fatigue endurance, corrosion resistance and flexibility, allowing for a significant reduction in component parts, and reducing the need for fasteners and joints. Conventional methods for producing fibre-reinforced composite materials include impregnating reinforcing fibres with a curable matrix resin to form prepregs. This method is often called a “prepregging” method. Structural composite parts may be made by laying up multiple layers of prepregs on a mold surface followed by consolidation and curing. More recently, fibre-reinforced polymer composite parts are made by liquid resin infusion processes, which include Resin Transfer Molding (RTM) and Vacuum Assisted Resin Transfer Molding (VARTM). In a typical resin infusion process, a pre-shaped preform of dry fibrous materials is placed in a mold, then liquid resin is injected, usually under high pressure, into the mold in order to infuse the preform directly in-situ. The preform is composed of multiple, resin-free layers of reinforcing fibres or woven fabrics, which are laid up similarly to the way resin-impregnated prepregs are laid up. After resin infusion, the resin-infused preform is cured according to a curing cycle to provide a finished composite article. In resin infusion, the preform to be infused with the resin is a critical element—the preform is in essence the structural part awaiting resin. Liquid resin infusion technology is especially useful in manufacturing complex-shaped structures which are otherwise difficult to manufacture using conventional prepreg layup technologies. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration of the hybrid veil according to an embodiment of the present disclosure. FIG. 2 is a 3D reconstructed image obtained by Computerised Tomography of an actual hybrid veil that was formed by a wet-laid process. FIGS. 3A and 3B schematically illustrate a cured composite laminate containing a hybrid veil in the interlaminar region in comparison to a similar cured composite laminate containing a nonwoven veil with toughening particles scattered onto the veil's surface. FIGS. 4A and 4B schematically illustrate the forces acting on a composite laminate over a concave molding surface and a convex molding surface, respectively. FIGS. 5A-5D shows various embodiments for manufacturing a modified prepreg with hybrid veil(s) integrated therein. FIG. 6 schematically illustrates a woven fabric according to an embodiment of the present disclosure. FIG. 7 shows a top-view image of an exemplary hybrid veil taken by Scanning Electron Microscopy (SEM). FIGS. 8A and 8B show cross-sectional views of two cured composite panels, which are interleaved with different hybrid veils, showing the crack path propagation after being subjected to a GIc test. DETAILED DESCRIPTION A major weakness of conventional fibre/resin multilayered composites (or composite laminates) is their low interlaminar fracture toughness, which permits delamination of the composite layers upon impact of high energy force. Delamination occurs when two layers de-bond from each other. A cured composite with improved resistance to delamination is one with improved Compression Strength After Impact (CSAI) and fracture toughness. CAI measures the ability of a composite material to tolerate damage. In the test to measure CAI, the composite material is subject to an impact of a given energy and then loaded in compression. Fracture toughness is a quantitative way of expressing a material's resistance to brittle fracture when a crack is present and may be quantified as the strain energy release rate (Gc), which is the energy dissipated during fracture per unit of newly created fracture surface area. Gc includes GIc (Mode 1—opening mode) or GIIc (Mode II—in plane shear). The subscript “Ic” denotes Mode I crack opening, which is formed under a normal tensile stress perpendicular to the crack, and the subscript “IIc” denotes Mode II crack produced by a shear stress acting parallel to the plane of the crack and perpendicular to the crack front. The initiation and growth of a delamination is often determined by examining Mode I and Mode II fracture toughness. Because of the weak property in the through-thickness direction of the multilayere