Disclosure of Invention
In order to solve the defects in the prior art, the invention prepares the novel wood morph-genetic fiber water-lubricated composite material. Based on the academic concept of 'genetic state', the natural structure of wood is effectively inherited by an artificial method, and the chemical components are changed, so that the biological natural fine three-dimensional structure is prepared, and the special characteristics and functions are endowed by the selective composite material, so that the method has been intensively studied in the field of bionics, such as genetic material and the like. The term "genetic fiber" in the present invention is defined as a wood fiber which is inherited by the natural fine three-dimensional structure and is left after the lignin, hemicellulose and other components of the wood are removed. The fiber of wood is utilized, and mechanical properties such as strength, toughness and the like of the composite material can be improved through the three-dimensional structure of the fiber. The method comprises the steps of selectively removing adhesives such as lignin, hemicellulose and the like and parenchyma cells through bacteria treatment, alkali treatment and the like, so that wood fibers are separated in a large scale under the condition of almost no mechanical damage, and the fibers consist of cellulose nanofibers which are closely arranged and have strong hydrogen bonds and Van der Waals forces, and have high-strength and high-toughness properties. The invention fully utilizes the antifriction performance of the wood laser-induced graphene and the high-strength and high-toughness characteristics of the wood fiber to prepare the water-lubricated epoxy resin composite material with the self-lubricating characteristic, has important practical significance for development and utilization of novel water-lubricated composite materials, and is a brand new application for 'ecdysis' of plant fibers into high-end technological new materials.
The invention provides a water-lubricated composite material, which comprises a resin matrix and a fiber reinforcement, wherein the fiber reinforcement is wood morph-genetic fiber. The morph-genetic fiber is wood fiber with a natural three-dimensional structure of wood, and mainly plays a role in reinforcing and toughening.
Preferably, the resin matrix is epoxy resin, and graphene is distributed on the surface of the morph-genetic fiber material.
Any one of the above is preferable that the graphene is obtained by irradiating the surface of natural wood with laser light. In the prior art, graphene powder is mainly mixed with an epoxy resin material, and when the existing market micron-sized or nano-sized graphene powder is added into the epoxy resin and other materials, the problems of agglomeration and poor dispersibility are easy to occur. The wood laser-induced graphene disclosed by the invention does not relate to the problem of dispersion, is prepared on the surface of the wood, and is low in cost.
The water lubrication composite material provided by the invention preferably comprises graphene, a genetic fiber and epoxy resin, wherein the graphene is distributed on the surface of the genetic fiber material, and the graphene-genetic fiber is immersed in the epoxy resin. The wood surface modified graphene of the water-lubricated composite material provided by the invention plays a role in antifriction, and the mechanical properties of epoxy resin are improved by utilizing natural wood fibers and natural fine three-dimensional structures thereof, namely morph-genetic fibers. The novel environment-friendly water lubrication composite material with high strength, high toughness and low friction performance is prepared by using the natural wood fiber, and is a brand new application for 'sloughing' the plant fiber into a new high-end technological material.
The invention also provides a preparation method of the water-lubricated composite material, which comprises the following steps:
step 1: obtaining a laser-induced graphene material on the surface of the natural wood to obtain surface graphene wood;
step 2: performing delignification extraction treatment on the surface graphene wood obtained in the step 1 to obtain graphene-genetic fibers;
step 3: carrying out surface modification on the graphene-genetic fiber obtained in the step 2 through a coupling agent;
step 4: preparing an epoxy resin solution;
step 5: and (3) dipping the graphene-genetic fiber obtained in the step (3) into the epoxy resin solution obtained in the step (4) to obtain the graphene/genetic fiber/epoxy resin water lubrication composite material.
Preferably, in step 1, the natural wood is subjected to a drying treatment, and then the surface of the wood is irradiated with laser light under a gas-shielded environment to obtain the laser-induced graphene material on the surface of the wood.
The preferred scheme of step 1 comprises: firstly, drying natural wood at 100 ℃, and then irradiating the surface of the wood by laser in a gas protection environment to obtain the laser-induced graphene material on the surface of the wood.
Any of the above is preferred, the laser is CO selectable 2 The laser, near infrared picosecond and nanosecond laser, etc., the preferable laser feeding speed is 3-20 cm/s, the laser power is 1-30W, and the laser energy density is 100-1000J/cm 2 。
Any of the above is preferred by Ar and H 2 The gas is subjected to environmental protection, the flow rate of Ar shielding gas is 100-150 ml/min, and the flow rate of H2 shielding gas is 100-200 ml/min. Preventing oxidation of wood surface.
In any one of the above steps, in step 2, the surface graphene wood obtained in step 1 is preferably subjected to delignification extraction treatment by a sodium hydroxide aqueous solution.
The preferable scheme of the step 2 is as follows: and (3) carrying out delignification extraction treatment on the surface graphene wood obtained in the step (1) through a sodium hydroxide aqueous solution so as to achieve the purpose of removing substances such as lignin, hemicellulose and the like, and obtaining the surface graphene wood with a graphene layer and natural wood morph-genetic fiber material inside.
Preferably, any one of the above steps is that the concentration of the sodium hydroxide aqueous solution is 5% -12%, lignin and hemicellulose are extracted from wood under the boiling condition of the sodium hydroxide aqueous solution, the time is controlled to be 7-20 hours, then purified water is repeatedly cleaned for 2-4 times, and finally the wood is dried under the condition of 100 ℃ to obtain the graphene layer on the surface, wherein the graphene layer is the natural wood genetic fiber material, namely the graphene-genetic fiber.
The preferable scheme of the step 3 is as follows: and (3) carrying out surface modification on the graphene-genetic fiber obtained in the step (2) through a coupling agent, and enhancing interface combination of the surface of the genetic fiber and the epoxy resin.
In the step 3, the coupling method is that the graphene-morph-genetic fiber is soaked in a coupling agent-ethanol solution at the temperature of 45 ℃ for 4-8 hours; the coupling agent is a silane coupling agent or an anhydride coupling agent, and the mass fraction of the coupling agent is 0.1-1%. After the surface of the graphene and the surface of the genetic fiber are modified by the coupling agent, the problem of poor interfacial compatibility between the graphene and the resin is solved, so that the compatibility between the surface of the graphene and the genetic fiber and the resin is better.
In step 4, the viscosity of the epoxy resin solution is preferably 200 to 600 mPas at 30 ℃.
The preferable scheme of the step 4 is that the epoxy resin, the curing agent, the diluent, the antioxidant and the like are mixed and stirred to prepare the epoxy resin solution.
In any one of the above preferred processes, the preparation process is that the diluent, the antioxidant and the like are fully mixed and stirred with the epoxy resin in the room temperature environment, and then mixed with the curing agent for high-temperature curing to prepare the epoxy resin solution. The viscosity of the epoxy resin solution is 200-600 mPas at 30 ℃, wherein the viscosity of the epoxy resin is 5000-15000 mPas at 30 ℃ and the viscosity of the curing agent is 50-150 mPas at 30 ℃. The addition amount of the silane coupling agent or the anhydride coupling agent is 0.1-0.3%, and the addition amount of the diluent is determined according to the viscosity of the epoxy resin, so that the viscosity of the epoxy resin is adjusted to a proper viscosity range. The proper viscosity range refers to the viscosity of the epoxy resin solution at the temperature of 30 ℃ ranging from 200 mPa.s to 600 mPa.s.
The reagents used to prepare the epoxy resin solution are all conventional in the art, such as butanediol dioxygen diluent, antioxidant 1076.
The preferable scheme of the step 5 is that the graphene-genetic fiber obtained in the step 3 is subjected to vacuum negative pressure impregnation, and the epoxy resin solution obtained in the step 4 is cured at high temperature, so that the wood laser-induced graphene/genetic fiber/epoxy resin water lubrication composite material is obtained.
In any one of the above steps, preferably, in step 5, the graphene-genetic fiber obtained in step 3 is subjected to vacuum negative pressure impregnation with the epoxy resin solution obtained in step 4, the epoxy resin solution is impregnated at a vacuum degree of 200-1000 Pa and a temperature of 30-60 ℃ for 5-8 hours, the step is repeated for 2-4 times, and then the epoxy resin solution is cured for 24 hours in a heat treatment furnace at 80-120 ℃. The wood laser-induced graphene/genetic fiber/epoxy resin self-lubricating composite material is obtained. The composite material can realize the use of friction working conditions such as dry friction, water lubrication or oil lubrication.
The invention also provides the application of the water lubrication composite material and the preparation method thereof in at least one friction working condition of dry friction, water lubrication or oil lubrication.
Compared with the prior art, the wood laser-induced graphene/genetic fiber/epoxy resin water lubrication composite material and the preparation method thereof provided by the invention have the following advantages:
(1) The invention provides a wood laser-induced graphene, which is used for modifying the surface of wood by laser irradiation. During laser irradiation, the wood starts to be converted into amorphous carbon, which is converted into graphene after selectively absorbing laser energy. In the wood laser induction process, the selection of laser wavelength, power and shielding gas is critical to the formation of graphene, and the lignin content also directly influences the formation of graphene. The more lignin content of wood, the easier laser-induced graphene is formed. The graphene is modified on the surface of the wood in situ, so that the problems of easy agglomeration and poor dispersibility of the traditional graphene powder in epoxy resin are solved.
(2) The invention provides a wood morph-genetic fiber, which is a natural wood fiber and a natural three-dimensional structure thereof formed by removing substances such as lignin, hemicellulose and the like by using sodium hydroxide aqueous solution. The natural timber has simple components, but has mechanical properties of high strength, high toughness, impact resistance and the like through fine combination of complex structures. Therefore, the genetic fiber is used for impregnating the low-viscosity epoxy resin, so that the epoxy resin is fully filled into the inner pore canal of the genetic fiber to prepare the composite material, and the surface morphology and the natural three-dimensional structure of the fiber increase the mechanical properties such as the toughness and the like of the composite material.
(3) The water-lubricated composite material provided by the invention comprehensively utilizes the wood laser-induced graphene technology, the alkali liquor lignin removal technology and the vacuum impregnation epoxy technology, and utilizes low-cost wood and epoxy resin materials, so that the novel environment-friendly water-lubricated composite material is prepared, and the novel environment-friendly water-lubricated composite material is a brand new application of 'ecdysis' of plant fibers into a new high-end technological material.
Detailed Description
The present invention will be more clearly and fully described by the following examples, which are intended to be illustrative of only some, but not all, of the examples. The examples are presented to aid in understanding the invention and should not be construed to limit the scope of the invention in any way.
Unless defined otherwise, technical terms used in the following examples have the same meaning as commonly understood by one of ordinary skill in the art to which the inventive concepts pertain. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods are conventional methods unless otherwise specified.
Example 1
As shown in fig. 1, the preparation process of the wood laser-induced graphene/morph-genetic fiber/epoxy resin water-lubricated composite material is shown. Step 1, firstly drying wood at 100 ℃, and then irradiating the surface of the wood by laser in a gas protection environment to obtain the laser-induced graphene material on the surface of the wood. Laser selection of CO 2 Laser with laser feeding speed of 5cm/s, laser power of 6W, laserEnergy density 200J/cm 2 . By Ar and H 2 The gas is subjected to environmental protection, the flow rate of Ar protecting gas is 130ml/min, H 2 The flow rate of the shielding gas is 150ml/min.
And 2, performing lignin removal extraction treatment on the surface graphene wood obtained in the step 1 through a sodium hydroxide aqueous solution so as to achieve the purpose of removing substances such as lignin, hemicellulose and the like, and obtaining a surface graphene layer with natural wood morph-genetic fiber material inside. The concentration of the sodium hydroxide aqueous solution is 10%, lignin and hemicellulose are extracted from the wood bamboo under the boiling condition of the sodium hydroxide aqueous solution, the time is controlled to be 8 hours, deionized water is repeatedly cleaned for 2 times, and finally the wood bamboo is dried under the condition of 100 ℃ to obtain the natural wood genetic fiber material with the graphene layer on the surface.
And 3, carrying out surface modification on the graphene-genetic fiber obtained in the step 2 by using a coupling agent, and enhancing interface combination of the graphene and the genetic fiber surface and the epoxy resin. The mass fraction of the silane coupling agent is 0.1%, and the graphene-genetic fiber is soaked in the coupling agent-ethanol solution at 45 ℃ for 5 hours.
And 4, preparing an epoxy resin solution by using epoxy resin, a curing agent, a diluent, an antioxidant and the like. The preparation process includes mixing coupling agent, diluent, antioxidant, etc. with epoxy resin, and mixing with curing agent to prepare epoxy resin solution. The viscosity of the epoxy resin solution is 500 mPas at 30 ℃, wherein the viscosity of the epoxy resin is 10000 mPas at 30 ℃ and the viscosity of the curing agent is 100 mPas at 30 ℃. The addition amount of the diluent was 1%.
The preparation of the epoxy resin solution is a conventional technical scheme in the art, and reagents such as epoxy resin, curing agent, diluent, antioxidant and the like which can be used for preparing the epoxy resin solution in the prior art are suitable for the invention.
And 5, carrying out vacuum negative pressure impregnation on the graphene-genetic fiber obtained in the step 3 to obtain the epoxy resin solution obtained in the step 4, and curing to obtain the wood laser-induced graphene/genetic fiber/epoxy resin water lubrication composite material. And (3) immersing the wood in an epoxy resin solution at the vacuum degree of 500Pa and the temperature of 30 ℃ for 5 hours, repeating the step for 2 times, and curing for 24 hours in a heat treatment furnace at the temperature of 120 ℃ to obtain the wood laser-induced graphene/genetic fiber/epoxy resin water lubrication composite material.
The tribological performance of the composite material is tested by a UMT frictional wear testing machine in a room temperature environment, a ball-surface contact mode is adopted, the ball is made of GCr15 steel, the diameter is 8mm, the amplitude of reciprocating motion is 4mm, the load is 40N, the frequency is 10Hz, and the lubricating medium is deionized water. The results show that under the conditions of dry friction and water lubrication, the friction coefficient is smaller than 0.1, and a typical friction coefficient curve is shown in fig. 2. The water lubrication composite material provided by the invention provides technical support for developing novel environment-friendly low-friction high-wear-resistance water lubrication bearings for marine equipment, hydroelectric equipment and the like; is also a brand new search for 'metamorphic' wood into a new material for high-end science and technology.
The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.