RU2744893C1 - Polymer carbon fiber composition and method for its production - Google Patents

Abstract

FIELD: polymers.

SUBSTANCE: invention relates to polymer composite materials and a method for their production, intended as superstructure polymer materials. A polymer composition based on polyetheretherketone reinforced with a sized carbon fiber is intended as a superstructural polymer material, characterized in that a polyetheretherketone containing 20 wt. % filler, and as a filler, carbon fiber finished with hydroquinone is used, consisting of components, wt%: carbon fiber 96-98, hydroquinone 4-2. Also a method is described for producing a polymer composition based on polyetheretherketone intended as a superstructure polymer material, including sizing carbon fiber by applying a sizing component from a solution followed by drying, characterized in that the sizing component - hydroquinone - is applied from a solution with a mass fraction of 0.63- 1.25% hydroquinone in an organic solvent, then heating and distillation of the organic solvent are carried out according to the mode: 30°C - 30 min; 35°C - 30 min; 40°С - 30 min; 50°С - 30 min; 60°C - 30 min.

EFFECT: increased impact strength, breaking tensile stresses and relative elongation of the created polyetheretherketone carbon fiber composition due to the introduction of a finishing component - hydroquinone, which increases wettability of carbon fiber and increases intermolecular interactions between the filler and the polyetheretherketone matrix.

2 cl, 1 tbl, 5 ex

Description

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

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 composite materials 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 discloses 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, bull. No. 17 shows the compositions used for chain linking. 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 the carbon fibers are treated with it.

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 the invention of the Russian Federation No. 2057767 is given a polymer composite material, 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 an amount of 0.52-5.0% of the mass of the fiber at the following ratio of components, wt%: carbon reinforcing fibers containing the 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 deteriorate the dielectric properties of materials.

According to RF patent No. 2201423, polymer compositions are 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 carbon fiber with a 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 for 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 for wetting hydrophobic surfaces of 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 tensile strength values based on a matrix polymer of polyetheretherketone (PEEK) reinforced with sized carbon fiber (CF) 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 - hydroquinone (HQ), 1,4-dioxybenzene:

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

n = 140 ÷ 150

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

Carbon fiber 96 ÷ 98; Hydroquinone 4 ÷ 2;

The amount of finished carbon fiber in the composite material corresponds to 20 mass. %. 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 acetone, chlorinated organic solvents, dioxane, N, N-dimethylacetamide, mainly in acetone, then dried to constant weight.

The composites of the present invention are prepared by premixing a polymer matrix and a 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.

The following 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 the solution obtained by dissolving 0.5 g is poured (2 wt.%) HCN in 100 ml of acetone (0.63% 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 acetone is distilled off according to the mode: 30 ° С - 30 min .; 35 ° C - 30 min; 40 ° С - 30 minutes; 50 ° С - 30 minutes; 60 ° C - 30 min.

The sized fiber is dried in an oven under vacuum at 75-85 ° 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.%) HCN in 100 ml of acetone (0.78% 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 acetone is distilled off according to the mode: 30 ° С - 30 min .; 35 ° C - 30 min; 40 ° С - 30 minutes; 50 ° С - 30 minutes; 60 ° C - 30 min.

The sized fiber is dried in an oven under vacuum at 75-85 ° 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.%) HCN in 100 ml of acetone (0.94% 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 acetone is distilled off according to the mode: 30 ° С - 30 min .; 35 ° C - 30 min; 40 ° С - 30 minutes; 50 ° С - 30 minutes; 60 ° C - 30 min.

The sized fiber is dried in an oven under vacuum at 75-85 ° 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.%) HCN in 100 ml of acetone (1.1% 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 acetone is distilled off according to the mode: 30 ° С - 30 min .; 35 ° C - 30 min; 40 ° С - 30 minutes; 50 ° С - 30 minutes; 60 ° C - 30 min.

The sized fiber is dried in an oven under vacuum at 75-85 ° 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 the solution obtained by dissolving 1.0 g is poured (4 wt.%) HCN in 100 ml of acetone (1.25% 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 acetone is distilled off according to the mode: 30 ° С - 30 min .; 35 ° C - 30 min; 40 ° С - 30 minutes; 50 ° С - 30 minutes; 60 ° C - 30 min.

The sized fiber is dried in an oven under vacuum at 75-85 ° C for 2 hours.

From the finished hydrocarbons and PEEK, PCMs were obtained containing 20 wt. % HC (table 1).

Table 1

Properties of polyetheretherketone carbon fiber composites

Composition A _p , kJ / m
11 J, s / n σ rast,
MPa ε,% PEEK 450 + 20% HC 0.2 mm 7.0 132.2 3.7 Following example 1 7.1 133.6 3.72 Following example 2 7.3 135.7 3.78 Following example 3 7.6 137.8 4.3 Following example 4 7.5 137.5 3.75 Following example 5 7.4 136.2 3.73

where, A _p notched impact strength; σ _rast - tensile breaking stress; ε - relative elongation.

The data shown in the table show that composite materials containing sizing HC (examples No. 1-5) have higher values of impact strength, breaking tensile stresses and relative elongation compared to the unapplied sample (first line).

The technical result of the proposed invention is to increase the impact strength, breaking tensile stresses and elongation of the created polymer carbon fiber composition due to the introduction of a finishing compound - hydroquinone, which increases the wettability of carbon fiber and increases intermolecular interactions between the filler and the polyetheretherketone matrix.

Claims (3)

1. Polymer composition based on polyetheretherketone reinforced with finished carbon fiber, intended as a superstructure polymer material, characterized in that polyetheretherketone containing 20 wt% of a filler is used as a polymer matrix, and carbon fiber, finished with hydroquinone, consisting of components , wt%: Carbon fiber 96 - 98 Hydroquinone 4 - 2 2. A method of obtaining a polymer composition based on polyetheretherketone intended as a superstructure polymer material according to claim 1, comprising sizing carbon fiber by applying a sizing component from a solution followed by drying, characterized in that the sizing composition is applied from a solution with a mass fraction of 0.63 -1.25% in an organic solvent, then heating and distillation of the organic solvent are carried out according to the mode: 30 ° C - 30 min; 35 ° C - 30 min; 40 ° C - 30 min; 50 ° С - 30 min; 60 ° C - 30 min.