High-molecular polymer foam material and preparation method and application thereof
阅读说明：本技术 一种高分子聚合物发泡材料及其制备方法和应用 (High-molecular polymer foam material and preparation method and application thereof ) 是由 王超 孙慧婷 王廷梅 王齐华 于 2021-07-26 设计创作，主要内容包括：本发明涉及发泡材料技术领域,提供了一种高分子聚合物发泡材料及其制备方法和应用。本发明首先在聚合物中引入孔隙,然后将所得多孔聚合物进行超临界CO-2发泡,利用多孔聚合物自身的高比表面积,增加CO-2的扩散速率,加快气体溶解至聚合物达到饱和的时间。本发明提供的方法不仅适用于薄膜发泡,也适用于片材聚合物发泡,且适用于多种不同种类的聚合物,适应范围广泛。本发明制备的聚合物发泡材料内部为多级孔形貌,具有环境与内部互联性强、表面能低、比表面积大、传质效率高等优点,其中多级孔聚醚酰亚胺能够应用于摩擦润滑领域,多级孔的存在能够显著提高其含油率和高转速下的含油保持率。(The invention relates to the technical field of foaming materials, and provides a high molecular polymer foaming material and a preparation method and application thereof. The invention firstly introduces pores into the polymer, and then the obtained porous polymer is subjected to supercritical CO 2 Foaming, using the high specific surface area of the porous polymer itself to increase CO 2 The diffusion rate of (a) increases the time for the gas to dissolve until the polymer reaches saturation. The method provided by the invention is not only suitable for film foaming, but also suitable for sheet polymer foaming, and is suitable for various polymers, and the application range is wide. The polymer foam material prepared by the invention has the appearance of hierarchical pores inside, and has the advantages of strong environment and internal interconnectivity, low surface energy, large specific surface area, high mass transfer efficiency and the like, wherein the hierarchical pore polyetherimide can be applied to the field of friction lubrication, and the existence of the hierarchical pores can obviously improve the oil content and the oil content retention rate at high rotating speed.)
1. A preparation method of a high molecular polymer foaming material is characterized by comprising the following steps:
sintering high-molecular polymer powder after cold pressing to obtain a porous polymer;
subjecting the porous polymer to supercritical CO2Foaming to obtain the high molecular polymer foaming material.
2. The method of claim 1, wherein the high molecular weight polymer comprises polyphenylene sulfide, polysulfone, polymethyl methacrylate, polytetrafluoroethylene, polycarbonate, polystyrene, or polyetherimide.
3. The preparation method of claim 1, wherein the cold pressing time is 30-60 min, and the pressure is the forming pressure of the high polymer powder.
4. The method according to claim 1, wherein the sintering temperature is 20 to 100 ℃ or higher than the glass transition temperature of the high molecular polymer, and the sintering time is 1.5 to 3 hours.
5. The method of claim 1, wherein the porous polymer is subjected to supercritical CO2Before foaming, the method also comprises slicing the porous polymer, wherein the thickness of the slices is 1 mm-1 cm.
6. According to claimThe method of production described in 1, characterized in that supercritical CO2The foaming method comprises the following steps:
adsorbing the porous polymer with supercritical CO2And then foaming by a pressure relief method or a temperature rise method.
7. The method according to claim 2 or 6, wherein when the high molecular polymer is polysulfone, supercritical CO is adsorbed2The temperature is 140-200 ℃, the pressure is 8-15 MPa, and a pressure relief method is adopted for foaming;
when the high molecular polymer is polymethyl methacrylate, supercritical CO is adsorbed2The temperature is 70-120 ℃, the pressure is 8-15 MPa, and a pressure relief method is adopted for foaming;
when the high molecular polymer is polycarbonate, supercritical CO is adsorbed2Foaming at the temperature of 100-150 ℃ and under the pressure of 8-15 MPa, and foaming by a pressure relief method;
when the high molecular polymer is polystyrene, supercritical CO is adsorbed2Foaming at 70-100 ℃ and 10-30 MPa by adopting a pressure relief method;
when the high molecular polymer is polyetherimide, supercritical CO is adsorbed2Foaming temperature is 25-95 ℃, pressure is 9-30 MPa, and a heating method is adopted for foaming.
8. The foamed high molecular weight polymer material produced by the production process according to any one of claims 1 to 7, wherein the foamed high molecular weight polymer material has a hierarchical pore morphology.
9. The use of the foamed high molecular weight polymer material according to claim 8 in the field of friction lubrication, wherein the foamed high molecular weight polymer material is a hierarchical porous polyetherimide.
Technical Field
The invention relates to the technical field of foaming materials, in particular to a high molecular polymer foaming material and a preparation method and application thereof.
Background
The polymer foam material is a resin material with a large number of micropores in the matrix, compared with an unfoamed polymer, the density of the foam material can be reduced by 2-98%, the strength ratio and the rigidity ratio are improved by 3-6 times, and the polymer foam material has the advantages of high tensile strength, high impact modulus, low dielectric constant and the like. The material is widely applied to the fields of daily article packaging, industry and agriculture, automobile manufacturing industry, military aviation and aerospace, energy storage materials and the like.
Foaming of polymers typically requires the use of chemical blowing agents such as azobisisobutyronitrile, azobisformamide, and the like. However, chemical blowing agents are generally toxic and produce by-products which are detrimental to subsequent operations and are unsuitable for use in high temperature resistant polymers due to their low decomposition temperature.
Supercritical CO with inert gas2The foaming technology is a green preparation technology which is nontoxic, pollution-free and simple to operate, does not produce byproducts and basically does not change the mechanical properties of the polymer. Supercritical CO2Has high diffusivity and solubility of gas and liquid and CO2Are less polar and are capable of dissolving in non-polar or less polar polymers. Introduced supercritical CO2Dissolved in the polymerIn the material, a polymer-gas homogeneous system is formed, the glass transition temperature of the polymer can be reduced due to the plasticizing capacity of the polymer-gas homogeneous system, and the polymer porous material with excellent bubble appearance and uniform distribution is prepared through a quick pressure relief foaming or temperature rise oil bath foaming mode.
However, the supercritical CO is currently used2In the presence of CO in the foaming process2The problem of too long saturation time limits most of research to film foaming, and the research on sheet foaming is less, especially on high-performance special engineering plastics is less, so that the application in industrial production is greatly limited.
Furthermore, conventional supercritical CO is used2The polymer foaming material prepared by the foaming method has single pore diameter, when the polymer foaming material is used as a porous self-lubricating polymer in the field of friction lubrication, the circular supply and the suck-back of lubricating oil can be realized only at one rotating speed, once the centrifugal force is changed, the continuous oil supply can not be realized, and a lubricating oil film can not be continuous and stable, so that the friction wear is enhanced.
Disclosure of Invention
In view of this, the invention provides a high molecular polymer foam material, a preparation method and an application thereof. The method provided by the invention is suitable for various polymers, is not only suitable for film foaming, but also suitable for sheet polymer foaming, and the obtained high polymer foaming material has hierarchical pores, so that when the method is applied to the field of friction lubrication, the oil content and the oil retention rate are high.
In order to achieve the above object, the present invention provides the following technical solutions:
a preparation method of a high molecular polymer foaming material comprises the following steps:
sintering high-molecular polymer powder after cold pressing to obtain a porous polymer;
subjecting the porous polymer to supercritical CO2Foaming to obtain the high molecular polymer foaming material.
Preferably, the high molecular polymer includes polyphenylene sulfide, polysulfone, polymethyl methacrylate, polytetrafluoroethylene, polycarbonate, polystyrene, or polyetherimide.
Preferably, the cold pressing time is 30-60 min, and the pressure is the molding pressure of the high polymer powder.
Preferably, the sintering temperature is 20-100 ℃ above the glass transition temperature of the high molecular polymer, and the time is 1.5-3 h.
Preferably, the porous polymer is subjected to supercritical CO2Before foaming, the method also comprises slicing the porous polymer, wherein the thickness of the slices is 1 mm-1 cm.
Preferably, supercritical CO2The foaming method comprises the following steps:
adsorbing the porous polymer with supercritical CO2And then foaming by a pressure relief method or a temperature rise method.
Preferably, when the high molecular polymer is polysulfone, supercritical CO is adsorbed2The temperature is 140-200 ℃, the pressure is 8-15 MPa, and a pressure relief method is adopted for foaming;
when the high molecular polymer is polymethyl methacrylate, supercritical CO is adsorbed2The temperature is 70-120 ℃, the pressure is 8-15 MPa, and a pressure relief method is adopted for foaming;
when the high molecular polymer is polycarbonate, supercritical CO is adsorbed2Foaming at the temperature of 100-150 ℃ and under the pressure of 8-15 MPa, and foaming by a pressure relief method;
when the high molecular polymer is polystyrene, supercritical CO is adsorbed2Foaming at 70-100 ℃ and 10-30 MPa by adopting a pressure relief method;
when the high molecular polymer is polyetherimide, supercritical CO is adsorbed2Foaming temperature is 25-95 ℃, pressure is 9-30 MPa, and a heating method is adopted for foaming.
The invention also provides the high molecular polymer foam material prepared by the preparation method in the scheme, and the high molecular polymer foam material has a hierarchical pore morphology.
The invention also provides application of the high molecular polymer foam material in the scheme in the field of friction lubrication, wherein the high molecular polymer foam material is hierarchical porous polyetherimide.
The invention provides a preparation method of a high molecular polymer foaming material, which comprises the following steps: sintering high-molecular polymer powder after cold pressing to obtain a porous polymer; subjecting the porous polymer to supercritical CO2Foaming to obtain the high molecular polymer foaming material. The invention firstly introduces pores into the polymer, and then the polymer containing the pores is subjected to supercritical CO2Foaming, the high specific surface area of the porous polymer material is utilized, and CO is greatly increased2Diffusion rate of (A) so that CO2The gas can enter and be absorbed into the polymer material matrix more easily, the time from the gas dissolution to the polymer saturation is shortened, and a multi-level pore morphology is formed in the polymer, so that the coupling of large pores and small pores is realized; the results of the examples show that the cellular polymer sheet CO is obtained under the same thickness and the same microcellular foaming conditions2The adsorption amount of the porous polymer is far higher than that of a solid polymer sheet, and because the pores in the porous polymer exist, the relatively thick polymer foamed sheet can be prepared in a relatively short time under suitable foaming conditions, and the porous polymer has great significance in industrial production.
The method provided by the invention is not only suitable for film foaming, but also suitable for sheet polymer foaming, and is suitable for various molded polymers, such as polyphenylene sulfide, polysulfone, polymethyl methacrylate, polytetrafluoroethylene, polycarbonate, polystyrene, polyetherimide and the like, and the method has wide adaptability.
Furthermore, the aperture and the porosity of the high molecular polymer foam material can be changed by controlling the parameters of the preparation process, so that the high molecular polymer foam material with different apertures and porosities can be conveniently prepared according to actual needs.
The invention also provides the high molecular polymer foam material prepared by the preparation method in the scheme. The high molecular polymer foaming material prepared by the invention has a multi-stage pore morphology and has wide application prospects in the fields of biomedical treatment, catalysis, adsorption, mechanical engineering and the like.
The invention also provides application of the high molecular polymer foam material prepared by the preparation method in the scheme in the field of friction lubrication, in particular application of the hierarchical porous polyetherimide in the field of friction lubrication. Compared with the polyetherimide with a single pore diameter, the prepared multi-pore polyetherimide has the advantages of high environmental and internal interconnectivity, low surface energy, large specific surface area, high mass transfer efficiency and the like, has higher oil content, and lubricating oil in large pores is thrown out at first under a large centrifugal force, but the multi-pore polyetherimide still can keep certain oil content at a high rotating speed due to the existence of the nano-scale pores, so that the oil content retention rate of a material is increased, the service life of a bearing retainer is prolonged, and the multi-pore polyetherimide has a wide application prospect.
Drawings
FIG. 1 is a representation of the CO of the porous polyetherimide and solid polyetherimide of example 12A graph of adsorption amount versus time;
FIG. 2 is an SEM image of a multi-hole polyetherimide made according to example 1;
FIG. 3 is a graph showing the CO of the porous polyetherimide and the solid polyetherimide of example 22A graph of adsorption amount versus time;
FIG. 4 is a graph of the CO of the porous polyetherimide and the solid polyetherimide of example 32A graph of adsorption amount versus time;
FIG. 5 is a graph of the pore size test results for the porous polyetherimide of example 3;
FIG. 6 is a graph of the pore size test results for the hierarchical pore polyetherimide in example 3;
FIG. 7 is a graph showing the results of pore size measurement of porous polystyrene in example 4;
FIG. 8 is an SEM photograph of a multi-cellular polystyrene of example 4;
FIG. 9 is a graph showing the results of the oil retention test of multi-well PEI and single-well PEI in example 5 at different rotational speeds.
Detailed Description
The invention provides a preparation method of a high molecular polymer foaming material, which comprises the following steps:
sintering high-molecular polymer powder after cold pressing to obtain a porous polymer;
subjecting the porous polymer to supercritical CO2Foaming to obtain the high molecular polymer foaming material.
According to the invention, high-molecular polymer powder is sintered after being cold-pressed, so that the porous polymer is obtained. In the present invention, the high molecular polymer preferably includes polyphenylene sulfide, polysulfone, polymethyl methacrylate, polytetrafluoroethylene, polycarbonate, polystyrene, or polyetherimide.
In the present invention, the high molecular polymer powder is preferably dried and sieved before cold pressing; the invention has no special requirement on the aperture of the sieving, and the selection is carried out according to the type of the specific high molecular polymer, in the specific embodiment of the invention, the larger the particle size of the high molecular polymer powder is, the larger the aperture of the obtained porous polymer is; specifically, the particle size of the polystyrene powder is preferably 40-58 μm, and the particle size of the polyetherimide powder is preferably 130-180 μm; the particle size is the particle size of the sieved high molecular polymer powder.
In the invention, the cold pressing temperature is preferably room temperature, the time is preferably 30-60 min, the cold pressing pressure is the molding pressure of the high molecular polymer, and an appropriate molding pressure is set according to the type of the high molecular polymer, in a specific embodiment of the invention, the molding pressure of the polyetherimide powder is preferably 3-10 MPa, and the molding pressure of the polystyrene powder is preferably 1.5 MPa. In the present invention, the cold pressing is preferably performed by putting the high molecular polymer powder into a mold and performing cold pressing in a press vulcanizer.
In the invention, the sintering temperature is preferably 20-100 ℃ above the glass transition temperature of the high molecular polymer, and the time is preferably 1.5-3 h; in a specific embodiment of the invention, the temperature of the polyetherimide is preferably 250-350 ℃. In the sintering process, the mutually contacted parts among the high molecular polymer powder particles are fused together, and the pores among the powder particles are gradually connected to form mutually penetrated pore channels, so that the porous polymer with a certain pore diameter and porosity is obtained.
After sintering is completed, the present invention preferably cools the sintered product to room temperature, and then sequentially performs ethanol washing and drying to obtain a porous polymer.
After the porous polymer is obtained, the invention carries out supercritical CO on the porous polymer2Foaming to obtain the high molecular polymer foaming material. In the present invention, the porous polymer is subjected to supercritical CO2Before foaming, the method also comprises slicing the porous polymer, wherein the thickness of the slices is preferably 1 mm-1 cm, and more preferably 2 mm-8 mm.
In the present invention, the supercritical CO2The foaming process preferably comprises: adsorbing the porous polymer with supercritical CO2Until saturation, then foaming by adopting a pressure relief method or a temperature rise method; the invention has no special requirements on the specific operating conditions of the pressure relief method or the temperature rise method, and the conditions well known by the technicians in the field can be adopted; in a specific embodiment of the invention, the pressure relief foaming is specifically to release pressure to normal pressure within 2 s; the heating foaming method is specifically characterized in that the polymer subjected to pressure relief (pressure relief to normal pressure within 2 s) is subjected to oil bath foaming for 1-15 min at the temperature close to the glass transition temperature; after the foaming is completed, the obtained porous material is preferably placed in an ice-water bath for cooling and shaping. In the embodiment of the present invention, the high molecular weight polymer having a glass transition temperature of 200 ℃ or higher is preferably foamed by an elevated temperature method, and the high molecular weight polymer having a glass transition temperature of less than 200 ℃ is preferably foamed by a pressure-releasing method.
In the present invention, it is preferable that the porous polymers are all placed in supercritical CO2Introducing 0.5MPa CO into the autoclave2Purging to remove excessive water and air in the kettle, and performing supercritical CO under foaming condition2After the adsorption is saturated, foaming is carried out by adopting a pressure relief or temperature rise method, and the supercritical CO is used2The adsorption conditions and the specific foaming method of (2) are preferably set in accordance with the type of the high molecular polymer, and specifically: when the high molecular polymer is polysulfone, supercritical CO is adsorbed2At a temperature of 140 to 200 ℃ and a pressure of 8 to 1Foaming at 5MPa by adopting a pressure relief method; when the high molecular polymer is polymethyl methacrylate, supercritical CO is adsorbed2The temperature is 70-120 ℃, the pressure is 8-15 MPa, and a pressure relief method is adopted for foaming; when the high molecular polymer is polycarbonate, supercritical CO is adsorbed2Foaming at the temperature of 100-150 ℃ and under the pressure of 8-15 MPa by adopting a pressure relief method; when the high molecular polymer is polystyrene, supercritical CO is adsorbed2Foaming at 70-100 ℃ and 10-30 MPa by adopting a pressure relief method; when the high molecular polymer is polyetherimide, supercritical CO is adsorbed2Foaming temperature is 25-95 ℃, pressure is 9-30 MPa, and a heating method is adopted for foaming.
In supercritical CO2In the foaming process, the specific surface area is large due to the existence of the plurality of pores, and CO is generated2The diffusion rate into the polymer matrix becomes fast, and compared with a solid non-porous sheet, the saturation time is greatly shortened; CO 22After entering the polymer matrix, the polymer is adsorbed not only on the nonporous polymer matrix but also around the wall of the macroporous hole, and as the gas nuclei grow, the driving force disappears, and the gas nuclei stop growing to form the appearance of alternately arranged small holes and large holes.
The invention also provides the high molecular polymer foam material prepared by the preparation method in the scheme, and the high molecular polymer foam material has a hierarchical pore morphology.
The invention also provides application of the high molecular polymer foam material prepared by the preparation method in the scheme in the friction lubrication field, and particularly relates to application of the hierarchical pore polyetherimide prepared by the preparation method in the scheme in the friction lubrication field. The polyetherimide material is an excellent special engineering material, has excellent mechanical property and thermal property and good wear resistance, has a great application prospect in the field of friction lubrication, but the existing porous polyetherimide has a single pore diameter, the glass transition temperature of the polyetherimide is higher, and the processing of a hierarchical pore polyetherimide sheet is difficult. The invention passes supercritical CO2Foaming introduces new materials into porous polyetherimide with certain porosityCompared with polyetherimide with single pore diameter before foaming, the introduced nano-scale pore does not change the porosity of the polyetherimide basically, so that the influence on the thermal property and the mechanical property is small, and the application of the polyetherimide in the mechanical field is not influenced. In addition, compared with the polyetherimide with a single pore diameter, the multi-level pore polyetherimide with the large pore-small pore coupling pore structure provided by the invention has higher oil content, and lubricating oil in large pores is firstly thrown out under a larger centrifugal force, but the multi-level pore polyetherimide still can keep a certain oil content at a high rotating speed due to the existence of the nano-level pore, so that continuous oil supply is realized, a lubricating oil film is continuous and stable, and the service life of a bearing retainer is prolonged.
In the present invention, the method of application is preferably: and (2) dipping the hierarchical-pore polyetherimide in lubricating oil until saturation to obtain a hierarchical-pore oily material, and using the hierarchical-pore oily material as an oily bearing. In the invention, the impregnation is preferably carried out under vacuum conditions, the temperature of the impregnation is preferably 120 ℃, the pressure is preferably less than 0.08MPa, the time is preferably 10-60 h, and the lubricating oil is preferably PAO10, PAO4 or amino silicone oil.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention.
Example 1
(1) And (3) putting the dried polyetherimide powder with the particle size of 130-180 mu m into a mold, and maintaining the pressure in a flat vulcanizing machine at 5MPa and room temperature for 30min to be pressed into a flaky solid. The resulting porous polyetherimide (designated porous PEI) was then sintered in a sintering furnace at 300 ℃ for 2.5 hours to yield a porous polyetherimide and mercury intrusion analysis of the porous polyetherimide revealed a porous PEI with an average pore size of 9.6 microns and a porosity of 20%.
Meanwhile, a solid nonporous PEI sheet is prepared for comparison, and the preparation method comprises the following steps: and (3) putting the PEI powder into a die, sintering at 280 ℃ and 10MPa, and cooling to obtain the solid non-porous PEI.
(2) The resulting porous PEI was cut into 2mm and 7mm thin slices, designated 2mm-porous and 7mm-porous, respectively, and solid, non-porous PEICut into 2mm sheets, designated 2mm-non-porous, placed in an autoclave and charged with 0.5MPa of CO2And (4) purging to remove excessive water and air in the kettle.
(3) Setting foaming conditions at 25 ℃ and 15MPa, subjecting 2mm-porous, 7mm-porous and 2mm-non-porous to supercritical CO2Adsorbing, taking out at intervals, weighing and calculating CO of different PEI samples2The adsorption quantity is calculated by the formula shown in formula I;
in formula I: m isiFor adsorbing CO2Weight of the latter sample, m0Is the original weight of the sample.
2 mm-and 7 mm-and 2mm-non-porousCO at different times2As shown in FIG. 1, it can be seen from FIG. 1 that the adsorption amount of 2mm porous PEI is much higher than that of solid PEI, and that the adsorption amount of 2mm porous polyetherimide is CO2The highest adsorption amount of the catalyst reaches 12.5 percent; meanwhile, the adsorption capacity of 7mm porous PEI is much higher than that of solid nonporous PEI, because the existence of internal pores greatly increases CO2Diffusion rate of (A) so that CO2More readily enter and adsorb inside the polymeric material matrix.
(3) When CO is present2And when the adsorption capacity reaches the maximum value, quickly unloading and taking out the high-pressure kettle, quickly transferring the high-pressure kettle into a high-temperature oil bath at the temperature of 220 ℃ within 2s, foaming the high-temperature oil bath for 1min, taking out the high-temperature oil bath, and placing the high-temperature oil bath for cooling and shaping to obtain the multi-hole polyetherimide.
The porosity of the obtained hierarchical porous polyetherimide is 23% through testing, and the hierarchical porous polyetherimide can be observed to have the hierarchical porous morphology through SEM; FIG. 2 is an SEM image of a multi-pore polyetherimide.
Example 2
Steps (1) to (3) are the same as in example 1, and steps (4) to (5) are as follows:
(4) setting the foaming conditions at 35 ℃ and 15MPa, and adding 2mm-and 7 mm-and 2mm-non-porous for supercritical CO2Adsorbing, taking out at intervals, weighing and calculating CO of different PEI samples2The adsorption capacity is calculated by the formula I, and CO is obtained at different times2The adsorption amount of (b) is shown in FIG. 3;
as can be seen from FIG. 3, the temperature is higher and CO is higher in this example than in example 12Has a fast diffusion rate, 2mm porous PEI and 7mm porous PEI CO2The adsorption capacity reaches a maximum at the same time rapidly, but the temperature increases and CO is discharged2The density of (2) is reduced, so the adsorption capacity is about 9.2% at most; and the adsorption capacity of the porous PEI is much higher than that of the solid PEI.
(5) When CO is present2When the adsorption capacity reaches the maximum value, quick pressure relief is taken out from the high-pressure kettle, the pressure relief time is within 2S, then the high-temperature oil bath is quickly transferred into the high-temperature oil bath, the foaming time is taken out for 1min, the high-temperature oil bath is placed for cooling and shaping, the multi-stage hole polyetherimide is obtained, and the multi-stage hole morphology can be observed through SEM.
Example 3
Steps (1) to (3) are the same as in example 1, and steps (4) to (5) are as follows:
(4) setting foaming conditions at 55 deg.C and 15MPa, subjecting 2mm-porous, 7mm-porous and 2mm-non-porous to supercritical CO2Adsorbing, taking out at intervals, weighing and calculating CO of different PEI samples2The adsorption capacity is calculated by the formula I, and CO is obtained at different times2The adsorption amount of (b) is shown in FIG. 4;
as can be seen from FIG. 4, the temperature is higher and CO is higher in this example than in examples 1 to 22The fastest diffusion rates of 2mm porous materials polyetherimide and 7mm porous polyetherimide of CO2The adsorption capacity reaches a maximum at the same time rapidly, but the temperature increases and CO is discharged2The adsorption amount is about 7.8% at the maximum because of the decrease in the density of (2). Due to the high temperature, the desorption rate is also higher, but the adsorption capacity of the porous polyetherimide is still much higher than that of the solid polyetherimide.
(5) When CO is present2When the adsorption capacity reaches the maximum value, the pressure is quickly removed from the high pressureTaking out the kettle, enabling the pressure relief time to be within 2S, then quickly transferring the kettle into a high-temperature oil bath pan, foaming the kettle for 1min, taking out the kettle, placing the kettle in an ice water bath for cooling and shaping to obtain the multi-stage hole polyetherimide, and observing the appearance of the multi-stage hole through SEM; the porosity of the obtained hierarchical porous polyetherimide is 23% through testing, two pore diameter peaks exist at the positions of 9.05 micrometers and 13.73 nanometers, a pore diameter test result graph of the obtained porous polyetherimide before foaming is shown in figure 5, a pore diameter test result graph of the obtained hierarchical porous polyetherimide after foaming is shown in figure 6, and according to figures 5-6, the fact that supercritical CO is adopted can be seen2After foaming, the coupling of big holes and small holes is realized in the polymer.
Example 4
(1) And (3) placing the dried polystyrene powder with the aperture of 40-58 mu m into a mold, and maintaining the pressure in a flat vulcanizing machine at room temperature and 1.5MPa for 30min to be pressed into a flaky solid. And then placing the polystyrene into a sintering furnace to be sintered for 2.5 hours at 120 ℃ to obtain porous polystyrene, wherein the obtained porous polystyrene is a blocky solid with certain pore diameter and porosity, and mercury intrusion analysis is carried out on the porous polystyrene, and the result shows that: the pore diameter of the porous polystyrene was 2.52 μm, the porosity was 21%, and the pore diameter test result of the porous polystyrene is shown in fig. 7.
(2) Cutting the obtained blocky porous polystyrene into slices, putting the slices into a high-pressure kettle, saturating for 2h under the conditions of 100 ℃ and 20MPa (namely, saturating for 2h after the temperature and the pressure in the kettle meet the requirements), then quickly relieving pressure within 2s, and placing the slices in a cold water bath to shape the cells to obtain the multi-level-pore polystyrene; the obtained hierarchical porous polystyrene has two pore size peaks at 0.28 μm and 91.23 μm and porosity of 76.87% through testing, and an SEM image of the hierarchical porous polystyrene is shown in FIG. 8, and as can be seen from FIG. 8, the hierarchical porous polystyrene has obvious hierarchical pore morphology.
Example 5
(1) The multi-pore polyetherimide prepared in example 3 was vacuum-impregnated with PAO10 lubricant oil at 120 ℃ and 0.08MPa respectively until the quality of the multi-pore polyetherimide did not change any more, and the lubricant oil on the surface of the material was wiped off with cotton cloth to obtain a multi-pore oil-containing polymer material.
(2) Testing the oil content of the multi-level hole oil-containing material by using a high-speed desk type centrifuge, centrifuging and throwing oil for 10min at 3000r, 5000r, 7000r and 10000r/min respectively, and then testing the oil content retention rate; the oil-containing time, the temperature and the vacuum degree are kept consistent at each rotating speed.
And (2) dipping the porous polyetherimide (namely the single-stage pore polyetherimide) obtained before foaming in the example 3 into lubricating oil, wherein the dipping conditions are the same as those in the step (1), so as to obtain a single-stage pore oil-containing material, and performing the same oil content and oil throwing tests on the single-stage pore oil-containing material, wherein the specific conditions are the same as those in the step (2).
The test results show that the oil content of the multi-stage pore polyetherimide is 12 percent, while the oil content of the single-stage pore polyetherimide is 10 percent.
The results of the oil retention after oil slinging are shown in FIG. 9, and it can be seen from FIG. 9 that at low rotation speed, due to the hierarchical porous polyetherimide in supercritical CO2The ratio of macropores is slightly increased under the treatment of (1), so the oil retention of the multi-stage porous polyetherimide is lower than that of the single-stage porous polyetherimide at low rotation speed, but the oil retention of the multi-stage porous polyetherimide is higher than that of the porous polyetherimide due to the existence of nanopores at high rotation speed.
Example 6
According to the mode of example 5, the hierarchical pore polyetherimide is dipped into PAO4 lubricating oil for 10-60 h at 120 ℃ under vacuum (below 0.08 MPa), until the quality of the hierarchical pore polymer material is not changed, the lubricating oil on the surface of the material is wiped off by cotton cloth, and the hierarchical pore oil-containing material is obtained. And (3) centrifuging and throwing oil for 10min at 3000r, 5000r, 7000r and 10000r/min, and testing the oil-containing retention rate after oil throwing.
The results show that due to the presence of nanopores, the oil retention of the multi-stage pore polyetherimides is higher at high rotational speeds than that of the single-stage pore polyetherimides.
Example 7
Other conditions were the same as in example 5, and only the lubricating oil was changed to amino silicone oil to obtain a multi-pore oil-containing material and a single-pore oil-containing material. And (3) centrifuging and throwing oil for 10min at 3000r, 5000r, 7000r and 10000r/min, and testing the oil-containing retention rate after oil throwing. The results show that due to the presence of nanopores, the oil retention of the multi-stage pore polyetherimides is higher at high rotational speeds than that of the single-stage pore polyetherimides.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.