Preparation method of oxygen-blocking and water-blocking polystyrene material capable of normally permeating hydrogen based on molecular weight regulation and control

Abstract

The invention discloses a preparation method of an oxygen-blocking water-blocking polystyrene material capable of normally permeating hydrogen based on molecular weight regulation, and relates to the technical field of high polymer materials. The preparation method comprises the following steps: putting polystyrene particles into a metal mold with a polyimide film arranged at the bottom, flatly spreading the polystyrene particles, uniformly distributing the polystyrene particles, putting a polyimide film above the mold, carrying out thermocuring, standing, and stripping from the metal mold, so as to obtain the polystyrene composite material. The molecular weight regulation-based oxygen-resistant and water-resistant polystyrene material capable of normally permeating hydrogen is obtained. The molecular weight regulation-based polystyrene material capable of resisting oxygen and water and enabling hydrogen to normally permeate is prepared by adopting the method provided by the invention; the problems that in the prior art, PS materials with different molecular weights have influences on the barrier property of water vapor and oxygen, the high selectivity of oxygen and water resistance and normal permeation of hydrogen is insufficient, and the sample preparation uniformity is insufficient are effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a method for preparing a polystyrene material which is oxygen- and water-resistant and can normally permeate hydrogen based on molecular weight regulation. Background Art

[0002] Hydrogen is a small gas component with high permeability. It can easily penetrate and accumulate in a closed environment. It reacts with metal materials to form brittle hydrides, which can cause plastic loss or even cracking of metal materials. Hydrogen accumulation in a closed environment also poses a risk of explosion, threatening environmental safety. Placing hydrogen-absorbing materials in a closed environment can effectively reduce the accumulation of hydrogen in a closed environment. 1,4-Bis(phenylethynyl)benzene is a typical irreversible hydrogen-absorbing material that can react with hydrogen under the action of a palladium / carbon catalyst to achieve the effect of hydrogen absorption. However, oxygen in a closed environment will react with hydrogen under the action of a palladium / carbon catalyst to generate water, which will not only reduce the hydrogen absorption effect, but also have a negative impact on the environment. Therefore, it is necessary to coat the hydrogen-absorbing particles with a highly selective film that blocks oxygen, water and hydrogen to prevent such reactions from occurring.

[0003] Polystyrene (PS) polymer material is a commonly used packaging material with low cost, good processability and thermal stability. It also has certain oxygen and water vapor barrier capabilities and is expected to be a candidate for highly selective coating materials that block oxygen, water and hydrogen. An expert team prepared a nanocomposite packaging sheet formed by ZnO nanoparticles and nanomontmorillonite with PS. The results showed that the oxygen permeability of PS material decreased with the increase of the addition amount of ZnO nanoparticles. The oxygen permeability of PS / 4.47% OMMT / 1.16% ZnO decreased the most, and decreased by 60% compared with pure PS. There is also an existing technology that first grafts hydrophobic poly (4-vinylbenzyl chloride) (p(VBC)) to the surface of graphene oxide (GO) by an in-situ free radical polymerization method to obtain a graphene oxide / poly (4-vinylbenzyl chloride) (GP(VBC)) composite material. Then it is added to the PS substrate to prepare PS composite materials with different filler ratios (5, 10, 15, 20 and 25wt%). The results showed that the water vapor permeability of the PS composite material with 5 wt% GP (VBC) composite filler was reduced by about 70% compared with the pure PS material, and its water vapor barrier performance was improved. PS microspheres encapsulated by several layers of GO nanosheets can also be synthesized by Pickering suspension polymerization to control the dispersion and orientation of GO nanosheets in the film coating, thereby showing efficient barrier properties. The results showed that the oxygen permeability of the PS / GO composite film with 2 wt% GO was 526.02 ± 55.78 cm 3 m -2 24h -1Compared with the PS film of the control group, its oxygen permeability was reduced by 96%, thereby improving the oxygen barrier performance of the PS material. GO was added as a filler to the mixture of PS / polymethyl methacrylate (PMMA) to prepare PS / PMMA / GO composites with different proportions. The results showed that the hydrogen permeability of the composite material with GO filler was higher than that of the composite material without GO filler. In addition, H 2 / CO 2 , H 2 / N 2 and H 2 / CH 4 The selectivity of the gas pairs was tested and characterized. The test results showed that the composite material with GO filler had a good selectivity for H 2 Highly selective.

[0004] However, in the prior art, there are still problems such as the influence of different molecular weight PS materials on their water vapor and oxygen barrier properties, insufficient high selectivity for oxygen and water barrier and normal hydrogen permeation, and insufficient uniformity of sample preparation. Existing research mainly focuses on improving the barrier properties of PS by adding nanomaterials, while ignoring the influence of PS molecular weight on its gas barrier properties, especially the influence of its oxygen barrier, water barrier and hydrogen permeation properties has hardly been reported. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for preparing a polystyrene material that is oxygen- and water-resistant and can pass hydrogen normally based on molecular weight regulation, which effectively solves the problems existing in the prior art of the influence of polystyrene materials with different molecular weights on the barrier properties of water vapor and oxygen, the lack of high selectivity for oxygen- and water-resistant and hydrogen-resistant materials, and the lack of uniformity in sample preparation.

[0006] To achieve the above object, the technical solution adopted by the present invention to solve the technical problem is: to provide a method for preparing a polystyrene material that is oxygen- and water-resistant and can normally permeate hydrogen based on molecular weight control, comprising the following steps: S1. Put polystyrene particles into a metal mold with a polyimide film at the bottom and spread them evenly, then place a piece of polyimide film on top of the mold; S2. Perform thermal curing, and peel off from the metal mold after standing to obtain a polystyrene material that is oxygen- and water-resistant based on molecular weight control and can transmit hydrogen normally.

[0007] Furthermore, in step S1, the molecular weight of the polystyrene is 192,000-350,000.

[0008] Furthermore, in step S1, the specification of the mold is 10-11 cm×10-11 cm.

[0009] Furthermore, in step S1, the specification of the mold is 10 cm×10 cm.

[0010] Furthermore, in step S1, the specification of the polyimide film is 12-13 cm×12-13 cm.

[0011] Furthermore, in step S1, the specification of the polyimide film is 12 cm×12 cm.

[0012] Further, in step S2, the film is placed on a hot press and heat cured at 210-230° C. and 5-7 MPa for 1.5-2.5 h.

[0013] Further, in step S2, the film is placed on a hot press and heat cured at 220° C. and 6 MPa for 2 h.

[0014] Further, in step S2, the mixture is allowed to stand at room temperature for 23-25 ​​hours.

[0015] Further, in step S2, the mixture is allowed to stand at room temperature for 24 hours.

[0016] The method for preparing the polystyrene material with oxygen and water barrier and hydrogen permeability based on molecular weight regulation produces the polystyrene material with oxygen and water barrier and hydrogen permeability based on molecular weight regulation.

[0017] The present invention has the following beneficial effects: 1. The present invention prepares polystyrene (PS) materials of different molecular weights by hot pressing, systematically characterizes their physical and chemical properties such as water contact angle, surface morphology, chemical composition and thermal stability, and analyzes the gas permeability of hydrogen, oxygen and water vapor. The water vapor barrier performance of the PS material initially decreases with the increase of molecular weight, and then increases. The oxygen permeability (OTR) increases with the increase of molecular weight, and low molecular weight polystyrene exhibits better oxygen barrier performance. Regarding hydrogen permeability (HTR), the change of molecular weight has little effect on polystyrene materials. Therefore, low molecular weight PS has better water barrier, oxygen barrier and hydrogen permeability high selectivity. In addition, the present invention also provides different composite material systems prepared by hot pressing of PS with different molecular weights and the same content of reduced graphene oxide (rGO), and further verifies the influence of its molecular weight on the water barrier, oxygen barrier and hydrogen permeability high selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Optical image of PS material at 200°C; Figure 2 Optical image of PS material at 240°C; Figure 3 Optical image of PS material at 220°C; Figure 4 This is the water contact angle test diagram; Figure 5 is the SEM image of PS1 prepared in Example 1; Figure 6 This is the SEM image of PS-R prepared in Comparative Example 4; Figure 7 This is the water vapor barrier test result diagram; Figure 8 This is the result diagram of oxygen barrier test; Fig. 9 This is a graph showing the results of the hydrogen barrier test. DETAILED DESCRIPTION

[0019] The principles and features of the present invention are described below, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. If no specific conditions are specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0020] Example 1 The method for preparing a polystyrene material that is oxygen- and water-resistant and can normally permeate hydrogen based on molecular weight regulation comprises the following steps: S1. Put polystyrene particles with a molecular weight of 192,000 into a 10×10 cm metal mold with a polyimide film at the bottom and spread them evenly, then place a piece of polyimide film on top of the mold; S2 was placed on a hot press and heat cured at 220°C and 6 MPa for 2 h. After standing for 24 h, it was peeled off from the metal mold to obtain a polystyrene material (PS1) that was oxygen- and water-resistant based on molecular weight control and could pass hydrogen normally.

[0021] Example 2 The method for preparing a polystyrene material that is oxygen- and water-resistant and can normally permeate hydrogen based on molecular weight regulation comprises the following steps: S1. Put polystyrene particles with a molecular weight of 280,000 into a 10×10 cm metal mold with a polyimide film at the bottom and spread them evenly, then place a piece of polyimide film on top of the mold; S2 was placed on a hot press and heat cured at 220°C and 6 MPa for 2 h. After standing for 24 h, it was peeled off from the metal mold to obtain a polystyrene material (PS2) that was oxygen- and water-resistant based on molecular weight control and through which hydrogen could pass normally.

[0022] Example 3 The method for preparing a polystyrene material that is oxygen- and water-resistant and can normally permeate hydrogen based on molecular weight regulation comprises the following steps: S1. Put polystyrene particles with a molecular weight of 350,000 into a 10×10 cm metal mold with a polyimide film at the bottom and spread them evenly, then place a piece of polyimide film on top of the mold; S2 is placed on a hot press and heat cured at 220°C and 6 MPa for 2 h. After standing for 24 h, it is peeled off from the metal mold to obtain a polystyrene material (PS3) that is oxygen- and water-resistant based on molecular weight control and can transmit hydrogen normally.

[0023] Comparative Example 1 A method for preparing a polystyrene composite material comprises the following steps: S1. Add reduced graphene oxide to polystyrene particles and stir evenly to obtain a mixture 1, wherein the molecular weight of the polystyrene is 192000, and the amount of reduced graphene oxide added is 1 wt%; S2. Place the mixture obtained in step S1 into a 10×10 cm metal mold with a polyimide film on the bottom and flatten it to make it evenly distributed. Then place a piece of polyimide film on the top of the mold, and then place it on a hot press. Heat cure it at 220°C and 6 MPa for 2 h. After standing for 24 h, peel it off from the metal mold to obtain a polystyrene composite material (PS1-G).

[0024] Comparative Example 2 A method for preparing a polystyrene composite material comprises the following steps: S1. Add reduced graphene oxide to polystyrene particles and stir evenly to obtain mixture 1, wherein the molecular weight of the polystyrene is 280,000, and the amount of reduced graphene oxide added is 1 wt%; S2. The mixture obtained in step S1 was placed in a 11×11 cm metal mold with a polyimide film on the bottom and spread evenly. A piece of polyimide film was placed on the top of the mold. The mold was then placed on a hot press and thermally cured at 210°C and 5 MPa for 1.5 h. After standing for 23 h, the mixture was peeled off from the metal mold to obtain a polystyrene composite material (PS2-G).

[0025] Comparative Example 3 A method for preparing a polystyrene composite material comprises the following steps: S1. Add reduced graphene oxide to polystyrene particles and stir evenly to obtain a mixture 1, wherein the molecular weight of the polystyrene is 350,000, and the amount of reduced graphene oxide added is 1 wt%; S2. Place the mixture obtained in step S1 into a 10×10 cm metal mold with a polyimide film on the bottom and flatten it to make it evenly distributed. Then place a piece of polyimide film on the top of the mold, and then place it on a hot press. Heat cure it at 230°C and 7 MPa for 2.5 h. After standing for 25 h, peel it off from the metal mold to obtain a polystyrene composite material (PS3-G).

[0026] Comparative Example 4 A method for preparing a polystyrene material comprises the following steps: S1. Put polystyrene particles with a molecular weight of 192000 into a 10×10 cm metal mold and spread them evenly. Then place them on a hot press and heat cure them at 220°C and 6 MPa for 2 h. After standing for 24 h, peel them off from the metal mold to obtain a polystyrene material (PS-R).

[0027] Comparative Example 5 A method for preparing a polystyrene material comprises the following steps: S1. Put polystyrene particles with a molecular weight of 192,000 into a 10×10 cm metal mold with a polyimide film at the bottom and spread them evenly, then place a piece of polyimide film on top of the mold; S2. Place it on a hot press and heat cure it at 200°C and 6 MPa for 2 h. After standing for 24 h, peel it off from the metal mold to obtain a polystyrene material.

[0028] Comparative Example 6 A method for preparing a polystyrene material comprises the following steps: S1. Put polystyrene particles with a molecular weight of 192,000 into a 10×10 cm metal mold with a polyimide film at the bottom and spread them evenly, then place a piece of polyimide film on top of the mold; S2. Place it on a hot press and heat cure it at 240°C and 6 MPa for 2 h. After standing for 24 h, peel it off from the metal mold to obtain a polystyrene material.

[0029] Test Example 1 The optical images of the polystyrene material with oxygen and water barrier and normal hydrogen permeability based on molecular weight control obtained in Example 1 and the polystyrene material obtained in Comparative Examples 5-6 are shown in FIG. Figure 1 As shown, the results of Comparative Example 6 are as follows Figure 2 As shown, the results of Example 1 are as follows Figure 3 shown.

[0030] Depend on Figure 1-Figure 3It can be seen that when the hot pressing temperature is 200°C, the polystyrene material is not completely melted, when the hot pressing temperature is 240°C, the polystyrene material appears yellow, and when the hot pressing temperature is 220°C, the polystyrene material appears white.

[0031] Test Example 2 The influence of different molecular weights on the wettability of the material surface was evaluated by testing the water contact angles of the oxygen- and water-blocking polystyrene materials PS1, PS2, and PS3 obtained in Examples 1-3 and the polystyrene composite materials PS1-G, PS2-G, and PS3-G obtained in Comparative Examples 1-3. The results are shown in FIG. Figure 4 As shown, Figure 4 Among them, (a) is the result of PS1, (b) is the result of PS2, (c) is the result of PS3, (d) is the result of PS1-G, (e) is the result of PS2-G, and (f) is the result of PS3-G.

[0032] Depend on Figure 4 It can be seen that since the surfaces of PS1, PS2 and PS3 materials and PS1-G, PS2-G and PS3-G composite materials all have a certain mirror reflection, the test graph of water contact angle also presents a mirror image. Figure 4 The solid-liquid-gas triple line is marked with a red dotted line. Compared with the static water contact angle of about 94° for the PS1 sample, the static water contact angles of the PS2 and PS3 samples decreased to about 88.7° and 86.6°, respectively, and the hydrophobicity was slightly reduced. The results show that the larger the molecular weight, the smaller the water contact angle of the PS sample, and the worse the hydrophobicity of the PS. Compared with the static water contact angle of about 95.5° for the PS1-G composite material, the static water contact angles of the PS2-G and PS3-G composite materials decreased to about 92.0° and 90.4°, respectively, and the hydrophobicity was also slightly reduced, confirming the above conclusion.

[0033] Test Example 3 The morphologies of the oxygen- and water-blocking and hydrogen-permeable polystyrene material PS1 obtained in Example 1 and the polystyrene material PS-R obtained in Comparative Example 4 were tested and characterized by SEM. The results are as follows: Figure 5 and Figure 6 shown.

[0034] Depend on Figure 5 and Figure 6 It can be seen that the surface of the polystyrene material PS1 obtained in Example 1, which is oxygen- and water-resistant and hydrogen-permeable based on molecular weight control, is relatively flat without obvious defects such as holes. However, the polystyrene material obtained in Comparative Example 4 has obvious hole defects on its surface because no polyimide film is placed during preparation.

[0035] Test Example 4 The water vapor permeability, oxygen permeability and hydrogen permeability of the polystyrene materials PS1, PS2, PS3 which are oxygen and water resistant and can normally permeate hydrogen based on molecular weight control obtained in Examples 1-3 and the polystyrene composite materials PS1-G, PS2-G, PS3-G obtained in Comparative Examples 1-3 were tested.

[0036] (1) Water vapor transmission rate The water vapor transmission rate test system (WVTR, C360M) provided by Labthink in China was used to evaluate the water vapor barrier performance of PS materials, which complies with the GB / T 1037-2021 standard. The test was carried out at a temperature of 23.0°C and a relative humidity of 51% RH. The results are as follows: Figure 7 shown.

[0037] Depend on Figure 7 It can be seen that the water vapor transmission rate of PS1 material is 1.50 g / m 2 ·Daily increase to 1.59 g / m for PS2 material 2 ·day, its water vapor barrier performance decreased. However, the water vapor permeability of PS3 material decreased to 1.27 g / m 2 The results show that with the increase of molecular weight, the water vapor barrier performance of PS material shows a trend of first decreasing and then increasing. Similarly, the water vapor barrier performance of PS1-G, PS2-G and PS3-G composite materials also shows the same trend of change, with the water vapor transmission rate increasing from 0.54 g / m2 of PS1-G composite material to 0.64 g / m2 of PS2-G composite material. 2 ·day first increased to 0.61 g / m for PS2-G composite 2 day, and then decreased to 0.48 g / m for PS3-G composite material 2 ·day.

[0038] (2) Oxygen permeability The oxygen barrier properties of PS materials were tested using an oxygen transmission rate tester (OTR) according to GB / T 19789-2005 standard. The test was conducted at a temperature of 23.0°C and a relative humidity of 51% RH. The results are as follows: Figure 8 shown.

[0039] Depend on Figure 8 It can be seen that the change law of the oxygen permeability of PS materials is that the oxygen permeability of PS1 material is 509.41 g / m 2 ·Daily increase to 1119.8 g / m2 for PS2 material 2 day, and then continued to increase to 4586.11 g / m 2·day. The results show that the oxygen permeability of PS material increases with the increase of molecular weight. The smaller the molecular weight, the better the oxygen barrier property of PS material. It can also be observed that the oxygen permeability of PS1-G, PS2-G and PS3-G composite materials are 40.72 g / m 2 day, 58.09 g / m 2 day and 138.32 g / m 2 ·day, its oxygen barrier performance also showed the same trend.

[0040] (3) Hydrogen permeability The hydrogen transmission rate (HTR) of PS materials was evaluated using the advanced flammable and explosive gas permeameter (GPT-H21) manufactured by China Saicheng. The results are as follows: Fig. 9 shown.

[0041] Depend on Fig. 9 It can be seen that the hydrogen permeability of PS1, PS2, and PS3 materials is 830 cm 2 / (m 2 ·day·0.1 MPa)、842 cm 2 / (m 2 ·day·0.1 MPa) and 907 cm 2 / (m 2 ·day·0.1 MPa). When the molecular weight of PS material changes, its hydrogen permeability does not change much overall, and PS material has almost no effect on hydrogen barrier. The hydrogen permeability of PS1-G, PS2-G, and PS3-G composite materials is 920 cm 2 / (m 2 ·day·0.1 MPa)、857 cm 2 / (m 2 ·day·0.1 MPa) and 912 cm 2 / (m 2 ·day·0.1 MPa), after adding rGO nanofiller, the hydrogen barrier properties of PS composites with three molecular weights did not change significantly.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a polystyrene material that is oxygen- and water-resistant and can pass hydrogen normally based on molecular weight control, characterized in that: The following steps are involved: S1. Put polystyrene particles into a metal mold with a polyimide film at the bottom and spread them evenly, then place a piece of polyimide film on top of the mold; S2. Perform thermal curing, and peel off from the metal mold after standing to obtain a polystyrene material that is oxygen- and water-resistant based on molecular weight control and can transmit hydrogen normally.

2. The method for preparing a polystyrene material that is oxygen- and water-resistant and hydrogen-permeable based on molecular weight control according to claim 1, characterized in that: In step S1, the molecular weight of the polystyrene is 192000-350000.

3. The method for preparing a polystyrene material that is oxygen- and water-resistant and can normally permeate hydrogen based on molecular weight control according to claim 1, characterized in that: In step S1, the size of the mold is 10-11 cm×10-11 cm.

4. The method for preparing a polystyrene material that is oxygen- and water-resistant and can normally permeate hydrogen based on molecular weight control according to claim 1, characterized in that: In step S1, the specification of the polyimide film is 12-13 cm×12-13 cm.

5. The method for preparing a polystyrene material that is oxygen- and water-resistant and can normally permeate hydrogen based on molecular weight control according to claim 1, characterized in that: In step S2, the film is placed on a hot press and heat cured at 210-230° C. and 5-7 MPa for 1.5-2.5 h.

6. The method for preparing a polystyrene material that is oxygen- and water-resistant and hydrogen-permeable based on molecular weight control as claimed in claim 1, characterized in that: In step S2, the mixture is allowed to stand at room temperature for 23-25 ​​hours.

7. A polystyrene material with oxygen and water barrier and hydrogen permeability based on molecular weight regulation, prepared by the method for preparing a polystyrene material with oxygen and water barrier and hydrogen permeability based on molecular weight regulation as described in any one of claims 1 to 6.

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