RU2757922C2 - Carbon fiber polymer composite material based on polyesteresterketone and a method for its preparation - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to polymer composite materials and a method for their preparation intended for use as super-constructive polymer materials. Carbon fiber polymer composite material contains as a polymer matrix polyesteresterketone, which is a product of polycondensation of 1,4-dioxybenzene and 4,4'-difluorodiphenyl ketone, and as a filler a composition is used that includes following components: carbon fiber in the amount of 95-98 wt.%, dressed with polyesteresterketone based on 4,4'-dioxydiphenylpropane and 4,4'-difluorodiphenyl ketone in the amount of 2-5 wt.%, wherein the amount of the filler in the polymer matrix is 10 wt.%. A method for producing carbon fiber polymer composite material includes carbon fiber dressing by applying a dressing component from a solution followed by drying, characterized in that a dressing composition is applied from a solution with a mass fraction of 0.3-0.78 % in dichloromethane, and a stepwise temperature rise is carried out with simultaneous distillation of a solvent according to the following regime: 25°C - 30 min.; 30°C - 30 min.; 35°C - 30 min.; 40°C - 30 min.; 75°C - 30 min.

EFFECT: treatment of carbon fibers with the dressing component, namely polyesteresterketone based on 4,4'-dioxydiphenylpropane and 4,4'-difluorodiphenyl ketone, allows one to obtain polymer composite characterized by increased impact strength, tensile yield strength, elastic modulus during stretching and bending.

2 cl, 1 tbl, 5 ex

Description

The invention relates to polymer composite materials and a method for their production, intended as superstructure polymer materials, including PEEK and HC, finished with polyetheretherketone based on 4,4'-dioxydiphenylpropane and 4,4'-difluorodiphenylketone.

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 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 with 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 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 cover the filler surface evenly enough.

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 may 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 sizing component, which is a polyetheretherketone based on 4,4'-dioxydiphenylpropane and 4,4'-difluorodiphenylketone (DPEC) of the formula:

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

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

Carbon fiber 95 ÷ 98; DPEC 5 ÷ 2;

The amount of finished carbon fiber in the composite material corresponds to 10 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 chlorinated organic solvents, dioxane, N, N-dimethylacetamide, mainly in dichloromethane, then dried to constant weight.

The composite materials 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 blend is extruded using a laboratory twin screw extruder with three heating zones at processing temperature conditions ^of 200 C, 315 ^C, 355 ^C. The used carbon fiber brand RK-306 (IFI Technical Production) and industrial grade PEEK polyetheretherketone 450 from here viscosity 0.32 dl / g, measured for a 1% solution in concentrated sulfuric acid.

Examples are presented below to illustrate 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, 24.0 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 (2.0 wt.%) DPEC in 120 ml of dichloromethane (0.3% 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 dichloromethane is distilled off according to the mode: 25 ° С - 30 min .; 30 ° С - 30 minutes; 35 ° C - 30 min; 40 ° С - 30 minutes; 75 ° C - 30 min.

A coated fiber is dried in an oven under vacuum at 85-95 ^{° C} 2 hour.

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, 24.25 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.%) DPEC in 120 ml of dichloromethane (0.47% 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 dichloromethane is distilled off according to the mode: 25 ° С - 30 min .; 30 ° С - 30 minutes; 35 ° C - 30 min; 40 ° С - 30 minutes; 75 ° C - 30 min.

A coated fiber is dried in an oven under vacuum at 85-95 ^{° C} 2 hour.

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, 24.125 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.%) DPEC in 120 ml of dichloromethane (0.55% 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 dichloromethane is distilled off according to the mode: 25 ° С - 30 min .; 30 ° С - 30 minutes; 35 ° C - 30 min; 40 ° С - 30 minutes; 75 ° C - 30 min.

A coated fiber is dried in an oven under vacuum at 85-95 ^{° C} 2 hour.

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, 24.0 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.%) DPEC in 120 ml of dichloromethane (0.62% 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 dichloromethane is distilled off according to the mode: 35 ° C - 30 min .; 40 ° С - 30 minutes; 45 ° C - 30 min; 55 ° C - 30 min; 75 ° C - 30 min.

A coated fiber is dried in an oven under vacuum at 85-95 ^{° C} 2 hour.

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, 23.75 g (95.0 wt.%) Of discrete HC with a fiber length of 0.2 mm is placed and the solution obtained by dissolving 1, 25 g (5.0 wt.%) DPEC in 120 ml of dichloromethane (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 dichloromethane is distilled off according to the mode: 35 ° C - 30 min .; 40 ° С - 30 minutes; 45 ° C - 30 min; 55 ° C - 30 min; 75 ° C - 30 min.

A coated fiber is dried in an oven under vacuum at 85-95 ^{° C} 2 hour.

From the finished hydrocarbons and PEEK, PCMs containing 10 wt. % HC (table 1).

Table 1

Properties of polyetheretherketone carbon fiber composites

Composition PTR,
r / 10 min A _p , kJ / m2
11 J
s / n E _exile ,
MPa E _rast , GPa σ _rast ,
MPa σ _tech ,
MPa PEEK 450 + 10% HC 0.2 mm 4.46 8.65 5.9 4.74 105 110.3 Following example 1 4.45 9.3 6.1 4.79 110 114.4 Following example 2 4.44 10.4 6.2 5.16 115 118.7 Following example 3 4.43 eleven 6.32 5.3 120 124 Following example 4 4.42 10.1 6.25 5.23 116 121.5 Following example 5 4.42 9.2 6.15 5.1 112 116.8

where, MFR is the melt flow rate, A _p is the impact strength, E ex is the modulus of elasticity in bending, σ _rast and E _rast are the breaking stress and modulus of elasticity in tension; σ _tech - tensile yield strength.

The data given in the table show that composite materials containing sizing HC (examples No. 1-5) have higher values of impact strength, breaking stress at tensile strength, tensile yield strength, tensile and bending moduli compared to unapplied sample (first line).

The technical result of the present invention is to increase the impact strength, breaking stress in tension, yield strength in tension, elastic moduli in tension and bending of the created polyetheretherketone carbon fiber composite by introducing a finishing component - polyetheretherketone based on 4,4'-dioxydiphenylpropane and 4.4 ' -difluorodiphenyl ketone of the formula:

,

,

which increases the wettability of the carbon fiber and increases the intermolecular interactions between the filler and the polyetheretherketone matrix.

Claims (9)

1. Carbon fiber polymer composite material based on polyetheretherketone, intended for use as a superstructure polymer material, characterized in that polyetheretherketone based on 1,4-dioxybenzene and 4,4'-difluorodiphenyl ketone is used as a polymer matrix, and in the amount of 10 wt.%, a composition is used that includes the following components: carbon fiber 95-98 wt.%; DPEC 2-5 wt%, while DPEC is a structure:

and the polymer matrix has the structural formula:

2. A method of producing a carbon fiber polymer composite material according to claim 1 based on polyetheretherketone, intended for use as a superstructure polymer material, including sizing carbon fiber by applying a sizing component, which is:

from a solution followed by drying, characterized in that the sizing composition is applied from a solution with a mass fraction of 0.3-0.78% in dichloromethane, and a stepwise rise in temperature is carried out with simultaneous distillation of the solvent according to the mode: 25 ° C - 30 min; 30 ° С - 30 min; 35 ° C - 30 min; 40 ° С - 30 min; 75 ° C - 30 min, after which the finished fiber is dried under vacuum at 85-95 ° C for 2 hours and mixed with a polymer matrix, which is:

using a high-speed homogenizer, and the amount of finished fiber is 10 wt. % of the composition of the mixture.