RU2741505C1 - Polyether ether ketone carbon-fiber composite and method for production thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a polyether-ether ketone carbon-fibre composite intended as a super-structural polymer material, as well as to a method of producing polyether ether ketone carbon-fibre composite. Polyether ether ketone carbon-fibre composite contains a polymer matrix and 20 wt. % filler. Polymer matrix used is polyether ether ketone. Filler used is carbon fibre, pre-treated with finishing component - polyhydroxyether. Filler contains the following ratio of components, wt. %: 96–98 carbon fibre, 2–4 polyhydroxyether. Method of producing polyether ether ketone carbon-fibre composite consists in the fact that carbon fibre is converted by mixing polyhydroxyether solution with mass fraction of 0.28–0.56 % in organic solvent with carbon fibre. Then, stepped temperature rise is performed with simultaneous solvent distillation according to the mode: 40 °C is 30 minutes; 50 °C is 30 minutes; 65 °C is 30 minutes; 75 °C is 30 minutes; 85 °C is 30 minutes. Then the dressed carbon fibre is dried, mixed with polyether ether ketone and polymer mixture is extruded.

EFFECT: invention increases wettability of the filler, increases intermolecular interactions between the carbon fibre and the polyetherether ketone matrix, andenables to obtain a composite material with high physical and mechanical properties.

3 cl, 1 tbl, 5 ex

Description

SUBSTANCE: invention relates to polymeric composite materials and a method for their production, intended as superstructure polymeric materials, including PEEK and HC, finished with polyhydroxether.

The development of many advanced technologies, for example, additive technologies, requires the use of composite materials with improved thermophysical and physical-mechanical characteristics. Low strength properties of many polymer composite materials (PCMs) are due to low interlayer interactions at the filler-polymer interface. It is possible to increase the adhesion between the polymer matrix and the filler using various finishing agents.

Known polymer compositions containing polyether ketones.

Patent EP 0224236 A2 is devoted to the creation of polymer compositions with improved chemical resistance and stable molding for injection molding, which contain polyether ketone (PEC), (not polyether ether ketone (PEEK)), aromatic polysulfone and fillers, including carbon fiber.

EP 0316681 A2 also describes fibrous composites of polyethersulfone, polypyrketone (not polyetheretherketone) and carbon fiber. Both patents describe composites made from a mixture of two polymers - polyethersulfone, polypyrketone, filled with fibers. They do not provide information on the sizing of carbon fibers to obtain PCMs with enhanced mechanical properties.

In the patent of the Russian Federation No. 2278126, publ. 20.06.2006, bul. No. 17, shows the compositions used for linking chains. In this work, it is proposed to use a mixture of polyether ketone (not PEEK) with terminal amino groups and copolymers of polyether sulfone (PES) and copolyether ether sulfone (PEES) with terminal anhydride groups. The mixture is dissolved in a high-boiling solvent - N-methylpyrrolidone and treated with carbon fibers.

The disadvantage of this solution is the use of a solvent with a high boiling point (203 ° C), which is difficult to remove from the composition, and its residues at high operating temperatures of products will lead to the appearance of bubbles in the castings, and as a result, to a decrease in operational properties.

It was not possible to find works devoted to composites consisting of "pure" polyetheretherketones and sized carbon fibers (HC) in the literature.

Various types of sizing additives are known from the prior art, which are used to create polymer composites. So, in the patent for invention RU 2057767, a polymer composite material is given, which includes a polysulfone polymer and carbon fibers. Carbon fibers contain on the surface as a finishing layer a copolymer consisting of units of methacrylic acid, diethylene glycol and benzosulfonic acid in a molar ratio from 49.5: 49.5: 1 to 49: 49: 2 in the amount of 0.52-5.0% of fiber mass at the following ratio of components, wt%: carbon fiber reinforcing, containing copolymer, 25-75; polysulfone matrix the rest. According to the authors of the invention, the use of the specified copolymer as a finishing layer makes it possible to increase the interlayer shear strength of polysulfone carbon plastics by 1.8-2.2 times.

The main disadvantage of the proposed solution is the use of an aqueous medium for applying a mixture of monomers to the carbon tape. Since carbon fibers and ribbons are hydrophobic, it is difficult to achieve a uniform distribution of an aqueous solution of a mixture of monomers. As a result of polymerization, incomplete conversion of monomers is also possible, which can lead to the formation and release of water at other stages of obtaining a polymer composite, which will lead to the formation of pores and a decrease in strength characteristics. The presence of benzenesulfonic acid in an aqueous medium will contribute to the accumulation of ions, which will worsen the dielectric properties of materials.

According to RF patent No. 2201423, polymer compositions were obtained from a polymer binder (sizing) and glass fabric or carbon filler. First, a binder, an oligomer, is obtained by the reaction of tetranitrile of aromatic tetracarboxylic acid and aromatic bis-o-cyanamine at temperatures of 170-180 ° C. The binder is obtained in powder form.

The main disadvantage of this solution is the complexity of the binder preparation process. With incomplete conversion of monomers during synthesis, the release of low molecular weight by-products of the reaction may occur during the combination of the binder with the filler at an elevated temperature, as a result of which voids will form in the composite material. This will lead to a deterioration in the strength characteristics of the material. In addition, powdered finishes may not evenly coat the filler surface.

Known polyetherimide composites according to US patent No. 4049613. To increase the wettability of the carbon fiber by the polymer matrix, the authors propose to keep the filler in hot nitric acid for three days, which is technologically and economically disadvantageous.

The closest analogue is the method of finishing carbon fiber according to RF patent No. 2054015 "Method for finishing carbon fiber for the production of polysulfone carbon fiber".

According to the proposed method, the block copolymer is mixed with a solvent. A block copolymer consisting of units of bismethacryloyloxydiethylene glycolphthalate and bismethacryloyloxy-triethylene glycolphthalate impregnates the carbon filler followed by drying to remove the solvent and polymerize the sizing film on the fiber, characterized in that mixing is carried out in water with simultaneous exposure to ultrasonic radiation from 15 to 44 kHz exposure from 5 to 14 minutes.

The disadvantages of this method are the use of aqueous solutions of block copolymers to wet the hydrophobic surfaces of the carbon fiber and the need for further polymerization on the surface of the filler. The consequence can be uneven wetting of the filler, and, consequently, a decrease in the properties of the resulting carbon fiber reinforced plastic.

The objective of the present invention is to obtain a composite material with higher physical and mechanical properties based on a matrix polymer of polyetheretherketone (PEEK) reinforced with sized carbon fiber (HC) and to develop a method for its production.

The task is achieved by the fact that composite materials reinforced with carbon fillers are obtained by pretreating carbon fiber with a finishing component, which is a polyhydroxyether (PGE) of the formula:

Matrix polyetheretherketone is an industrial polymer PEEK 450, which is a polycondensation product of 1,4-dioxybenzene and 4,4'-difluorobenzophenone of the formula:

In this case, the following ratios (wt%) of the components in the filler (HC + PGE) are taken:

Carbon fiber 96 ÷ 98 PSE 4 ÷ 2

The amount of finished carbon fiber in the composite material corresponds to 20% by weight. Such treatment with a sizing composition increases the wettability of the filler with polyetheretherketone, makes it possible to repeatedly carry out, if necessary, heat treatment of the resulting product without changing the properties of the sizing.

The carbon filler is coated with a sizing composition by treatment in chlorinated organic solvents, dioxane, N, N-dimethylacetamide, mainly in chloroform, and then dried to constant weight.

The composites of the present invention are prepared by premixing a polymer matrix and finished carbon fiber using a VLM-40B Multi function disintegrator high speed homogenizer. Then the polymer mixture is extruded using a laboratory twin-screw extruder with three heating zones at processing temperatures of 200 ° C, 315 ° C, 355 ° C. Used carbon fiber grade RK-306 (IFI Technical Production) and industrial polyetheretherketone grade PEEK 450 with a reduced viscosity of 0.32 dl / g, measured for a 1% solution in concentrated sulfuric acid.

Below are examples illustrating a method for producing finished carbon fibers.

Example 1

In a three-necked round-bottom flask equipped with a direct condenser, a device for supplying gaseous nitrogen, a heater and a mechanical stirrer, 24.5 g (98 wt.%) Of discrete HC with a fiber length of 0.2 mm is poured and a solution obtained by dissolving 0.5 g (2 wt%) PHE in 120 ml of chloroform (0.28% solution). Turn on the stirrer, supply nitrogen and stir for 30 minutes at room temperature. Next, the contents of the flask are heated and the chloroform is distilled off according to the following regime: 40 ° C - 30 min; 50 ° С - 30 min; 65 ° C - 30 min; 75 ° C - 30 min; 85 ° C - 30 min.

The sized fiber is dried in an oven under vacuum at 90-95 ° C for 2 hours.

Example 2

In a three-necked round-bottom flask equipped with a direct condenser, a device for supplying gaseous nitrogen, a heater and a mechanical stirrer, 24.375 g (97.5 wt.%) Of discrete HC with a fiber length of 0.2 mm is poured and the solution obtained by dissolving 0.625 g (2 , 5 wt.%) PGE in 120 ml of chloroform (0.35% solution). Turn on the stirrer, supply nitrogen and stir for 30 minutes at room temperature. Next, the contents of the flask are heated and the chloroform is distilled off according to the following regime: 40 ° C - 30 min; 50 ° С - 30 min; 65 ° C - 30 min; 75 ° C - 30 min; 85 ° C - 30 min.

The sized fiber is dried in an oven under vacuum at 90-95 ° C for 2 hours.

Example 3

In a three-necked round-bottom flask equipped with a direct condenser, a device for supplying gaseous nitrogen, a heater and a mechanical stirrer, 24.25 g (97.0 wt.%) Of discrete HC with a fiber length of 0.2 mm is poured, and the solution obtained by dissolving 0, 75 g (3 wt.%) PGE in 120 ml of chloroform (0.42% solution). Turn on the stirrer, supply nitrogen and stir for 30 minutes at room temperature. Next, the contents of the flask are heated and the chloroform is distilled off according to the following regime: 40 ° C - 30 min; 50 ° С - 30 min; 65 ° C - 30 min; 75 ° C - 30 min; 85 ° C - 30 min.

The sized fiber is dried in an oven under vacuum at 90-95 ° C for 2 hours.

Example 4

In a three-necked round-bottom flask equipped with a direct condenser, a device for supplying gaseous nitrogen, a heater and a mechanical stirrer, 24.125 g (96.5 wt.%) Of discrete HC with a fiber length of 0.2 mm is poured and the solution obtained by dissolving 0.875 g (3 , 5 wt%) PHE in 120 ml of chloroform (0.49% solution). Turn on the stirrer, supply nitrogen and stir for 30 minutes at room temperature. Next, the contents of the flask are heated and the chloroform is distilled off according to the following regime: 40 ° C - 30 min; 50 ° С - 30 min; 65 ° C - 30 min; 75 ° C - 30 min; 85 ° C - 30 min.

The sized fiber is dried in an oven under vacuum at 90-95 ° C for 2 hours.

Example 5

In a three-necked round-bottom flask equipped with a direct condenser, a device for supplying gaseous nitrogen, a heater and a mechanical stirrer, 24.0 g (96 wt.%) Of discrete HC with a fiber length of 0.2 mm is poured and a solution obtained by dissolving 1.0 g is poured (4 wt%) PGE in 120 ml of chloroform (0.56% solution). Turn on the stirrer, supply nitrogen and stir for 30 minutes at room temperature. Next, the contents of the flask are heated and the chloroform is distilled off according to the following regime: 40 ° C - 30 min; 50 ° С - 30 min; 65 ° C - 30 min; 75 ° C - 30 min; 85 ° C - 30 min.

The sized fiber is dried in an oven under vacuum at 90-95 ° C for 2 hours. PCMs containing 20 wt% HC were obtained from smoothed hydrocarbons and PEEK (Table 1).

Table 1

The data in the table show that composite materials containing sized HC (examples No. 1-5) have higher values of physical and mechanical properties compared to the uncoated sample (first line).

The technical result of the present invention is to improve the physical and mechanical properties of the created polyetheretherketone carbon fiber composite by introducing a finishing polymer that increases the wettability of the carbon fiber and increases intermolecular interactions between the filler and the polyetheretherketone matrix.

Claims (5)

1. Polyetheretherketone carbon fiber composite intended as a superstructural polymer material, including a polymer matrix and a filler, characterized in that polyetheretherketone is used as a polymer matrix; components, wt%: carbon fiber 96 ÷ 98 PSE 2 ÷ 4, while the carbon fiber composite contains 20 wt.% of the above filler, the amount of the finishing component to the carbon fiber is 2 ÷ 4 wt.%. 2. A method of obtaining a polyetheretherketone carbon fiber composite according to claim 1, which consists in the fact that the finishing of carbon fiber is carried out by mixing a solution of polyhydroxyether with a mass fraction of 0.28-0.56% in an organic solvent with carbon fiber, then a stepwise rise in temperature is carried out with simultaneous distilling off the solvent according to the mode: 40 ° С - 30 min; 50 ° С - 30 min; 65 ° C - 30 min; 75 ° C - 30 min; 85 ° C - 30 min, the sized carbon fiber is dried, then mixed with polyetheretherketone and extrusion of the polymer mixture is carried out. 3. A method according to claim 2, characterized in that the sizing component is applied from a chloroform solution.