A fiber composite lightweight and high-strength crosslinked polymer foam and its preparation method

Abstract

The present invention discloses a fiber-reinforced lightweight and high-strength crosslinked polymer foam and a preparation method thereof. By introducing a certain amount of fibers into a high-closed-cell-rate gel emulsion, the drying rate of the dispersed-phase moisture of the high-closed-cell-rate foam material can be significantly accelerated, the production efficiency can be remarkably improved, and the production cost can be reduced. In addition, the fiber-reinforced lightweight and high-strength polymer foam of the present invention has outstanding mechanical properties, especially impact toughness and bending properties. Generally speaking, the present invention can obtain a class of lightweight and high-strength crosslinked polymer foam materials with a wide density range, a high closed-cell rate, outstanding comprehensive mechanical properties, excellent medium resistance and heat resistance, and a relatively fast drying rate, which greatly promotes the industrialization process of preparing high-strength foam materials using gel emulsion as a soft template and the vigorous development of application fields with high requirements for "lightweight" and "high strength".

Description

Technical Field

[0001] The present invention belongs to the technical field of lightweight and high-strength porous materials, and particularly relates to a fiber-reinforced cross-linked polymer foam prepared by a gel emulsion soft template method and a preparation method thereof. Background Art

[0002] With the increasing requirements for the "energy-saving, environmental protection, lightweight, and high-strength" performance of materials in fields such as aerospace, marine ships, wind power, radar, transportation, electronic communication, and high-end sports goods, the research on materials with low density and high strength has become particularly important. The patent CN 110229263 B of this research group discloses a gel emulsion soft template-based lightweight and high-strength polymer material and its polymerization method. This lightweight and high-strength material is completed through three steps: the preparation of gel emulsion, the polymerization of gel emulsion, and the removal of dispersed-phase water. The density of this material can be adjusted within a wide range, it has a high closed-cell rate, and its comprehensive performance is excellent. However, during the gradual scale-up production process of this material, it is found that due to the high closed-cell rate being not conducive to the removal of dispersed-phase water in the material, the drying rate of the enlarged sample is slow. The slow drying rate will lead to a decrease in the production rate of the material, an increase in production energy consumption and costs, and seriously hinder the industrial scale-up and practical application process of this material. Summary of the Invention

[0003] The object of the present invention is to overcome the problems existing in the patent CN 110229263 B, and provide a fiber composite lightweight and high-strength cross-linked polymer foam with extremely high specific strength and specific modulus, good impact toughness, high bending and tensile properties, excellent resistance to media, a closed-cell rate of over 99%, and a relatively fast drying rate, as well as a preparation method thereof.

[0004] For the above object, the fiber composite lightweight and high-strength cross-linked polymer foam of the present invention is prepared by the following steps:

[0005] Step 1: Preparation of gel emulsion soft template

[0006] Under normal temperature and pressure, a gelling agent, a reactive monomer, a cross-linking agent, and an initiator are stirred evenly to form a continuous phase; then a dispersed phase is added to the continuous phase for emulsification to form a homogeneous, delicate, and non-flowing inverted gel emulsion; wherein, the gelling agent is any one or a mixture of multiple of cholesterol derivatives, iron tetroxide micro-nanoparticles, titanium dioxide micro-nanoparticles, silicon dioxide micro-nanoparticles, zinc oxide micro-nanoparticles, sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dibutylnaphthalene sulfonate, etc.; the reactive monomer is any one or a mixture of multiple of styrene, acrylonitrile, methyl methacrylate, tert-butyl methacrylate, etc.; the dispersed phase accounts for 10% - 75% of the total mass of the dispersed phase and the continuous phase.

[0007] Step 2: Preparation of fiber composite gel emulsion

[0008] The gel emulsion in Step 1 is compounded with the fibers treated with a silanizing agent to obtain a fiber composite gel emulsion; wherein, the addition amount of the fibers treated with the silanizing agent is 5% - 60% of the total mass of the continuous phase in the gel emulsion.

[0009] Step 3: Polymerization of the fiber composite gel emulsion

[0010] The mold filled with the fiber composite gel emulsion is placed in a water bath or an oven for initiation of polymerization. After the reaction is completed, demolding is carried out, and the demolded sample block is dried to a constant weight to obtain a fiber composite lightweight and high-strength cross-linked polymer foam.

[0011] Furthermore, in the above Step 1, when the reaction monomer is a mixture of styrene and acrylonitrile or methyl methacrylate or tert-butyl methacrylate, the addition amount of acrylonitrile or methyl methacrylate or tert-butyl methacrylate is 10% - 40% of the volume of styrene.

[0012] Furthermore, in the above Step 1, the cross-linking agent is any one or a combination of two of a difunctional cross-linking agent and a trifunctional cross-linking agent. The difunctional cross-linking agent is any one or a mixture of two of ethylene glycol dimethacrylate and hexanediol diacrylate. The trifunctional cross-linking agent is any one or a mixture of two of triallyl isocyanurate and trimethylolpropane trimethacrylate. The initiator is any one or a combination of multiple of azobisisobutyronitrile, azobisisoheptonitrile, benzoyl peroxide, cumene hydroperoxide, diisopropyl peroxydicarbonate, and tert-butyl peroxybenzoate.

[0013] Furthermore, in the above Step 1, the addition amount of the gelling agent is 0.5% - 5% of the total mass of the reaction monomer and the cross-linking agent. The total addition amount of the cross-linking agent is 10% - 50% of the total mass of the reaction monomer and the cross-linking agent, wherein the addition amount of the difunctional cross-linking agent is 5% - 40% of the total mass of the reaction monomer and the cross-linking agent, and the addition amount of the trifunctional cross-linking agent is 1% - 30% of the total mass of the reaction monomer and the cross-linking agent. The addition amount of the initiator is 0.5% - 3% of the total mass of the reaction monomer and the cross-linking agent.

[0014] Furthermore, in the above Step 1, the dispersed phase is any one of water, inorganic salt solution, organic compound solution, acid solution, and alkali solution that does not react with and is immiscible with the continuous phase.

[0015] Further, in the above step 2, the fiber is any one of glass fiber, carbon fiber, aramid fiber, etc., and the fiber structure is any one of fiber filaments, fiber mats, fiber cloths, fiber three-dimensional frameworks, etc.; among them, when the fiber is a fiber filament, fiber mat or fiber cloth, the composite method is layer laying composite, casting composite or impregnation composite, and the arrangement method of the fiber filaments is all the arrangement methods of common fiber composite resins, including but not limited to the arrangement combinations of 0°, 45°, 90°, etc.; when the fiber is a fiber three-dimensional framework, the composite method is casting composite, and the specific operation is: placing the fiber three-dimensional framework in a mold, pouring the prepared gel emulsion into the mold, and gently oscillating.

[0016] Further, in the above step 2, the silanizing agent is any one or a mixture of KH550, KH560, and KH570. The method for treating the fiber with the silanizing agent is: using a spraying or immersion method to perform surface treatment on the fiber with a 0.5% - 3% mass concentration ethanol solution of the silanizing agent, and placing it at room temperature for more than 24 h and then drying it at 50 - 60°C.

[0017] Further, in the above step 3, when the initiator is azobisisobutyronitrile, azobis(2,4-dimethylvaleronitrile), or benzoyl peroxide, the temperature for initiating polymerization is 30 - 90°C, and the reaction time is 4 - 12 h; when the initiator is cumene hydroperoxide, diisopropyl peroxydicarbonate, or tert-butyl peroxybenzoate, the process for initiating polymerization is: first pre-polymerizing at 30 - 80°C for 4 - 10 h, and then continuing to react at 90 - 150°C for 6 - 12 h.

[0018] The present invention discovers that for high-closed-cell foam materials with gel emulsion as the soft template, the drying of the dispersed-phase moisture includes two processes of "heat transfer" and "mass transfer", and the "heat transfer" and "mass transfer" rates determine the drying rate of the high-closed-cell materials. After introducing a certain amount of composite fibers, the fibers are distributed in a form that penetrates the dispersed phase and the continuous phase, and there are nanoscale gaps between the single-filament fibers and the continuous phase. These nanoscale gaps can significantly accelerate the "heat transfer" and "mass transfer" rates during the drying process of the material, and have no adverse effect on the mechanical properties of the material. Generally speaking, by introducing fibers with a certain proportion and surface silanization treatment, while ensuring the excellent mechanical properties of the fiber composite cross-linked polymer foam material, the drying rate of the dispersed-phase moisture of the high-closed-cell foam material can be significantly accelerated, the production efficiency can be significantly improved, the production cost can be reduced, and the industrialization process of preparing high-strength foam materials with gel emulsion as the template can be greatly promoted; in addition, while having a fast drying rate, the mechanical properties of the fiber composite cross-linked polymer foam, especially the impact toughness and bending properties, are significantly improved, which can strongly promote the development of application fields with high requirements for "light weight" and "high strength". Description of the Drawings

[0019] Figure 1It is the overall appearance, top surface and side view of the material in Example 4.

[0020] Figure 2 It is the appearance diagram of the fiber composite cross-linked polystyrene foam material in Example 2.

[0021] Figure 3 It is the appearance diagram of the fiber composite cross-linked polystyrene foam material in Example 9.

[0022] Figure 4 It is the sample for testing the bending performance of the fiber three-dimensional framework composite cross-linked polystyrene foam material in Example 5.

[0023] Figure 5 It is the SEM photo of the material in Example 4.

[0024] Figure 6 It is the nano-gap (mass transfer channel) between the fiber and the continuous phase in Example 4.

[0025] Figure 7 It is the nano-gap (mass transfer channel) between the fiber and the continuous phase in Example 9.

[0026] Figure 8 It is the SEM photo of the material in Example 12.

[0027] Figure 9 It is the comparison curve of the drying rates of the materials in Examples 3, 4 and Comparative Example 1.

[0028] Figure 10 It is the comparison curve of the drying rates of Example 2 and Comparative Example 3.

[0029] Figure 11 It is the comparison curve of the drying rates of Comparative Example 4 and Example 12.

[0030] Figure 12 It is the comparison of the bending performance between Comparative Example 3 and Example 2.

[0031] Figure 13 It is the comparison of the bending performance between Comparative Example 4 and Example 12. Detailed implementation manners

[0032] The present invention will be further described in detail below in conjunction with the drawings and examples, but the protection scope of the present invention is not limited to these examples only. Example 1

[0033] Step 1: Preparation of the gel emulsion soft template

[0034] At normal temperature and pressure, 50 g of cholesterol derivative, 6 L of styrene, 4 L of hexanediol diacrylate, and 50 g of azobisisobutyronitrile were added to a 60 L stirring kettle, and stirred to make the emulsion uniform to form a continuous phase; then 30 L of water was added to the continuous phase under stirring until a uniform, delicate, milky white gel emulsion that did not flow when inverted was formed.

[0035] Step 2: Preparation of fiber composite gel emulsion

[0036] Using the impregnation method, the gel emulsion from Step 1 was compounded with 500 g of glass fiber filaments in a mold with dimensions of 1604 mm×804mm×50 mm to obtain a fiber composite gel emulsion.

[0037] Step 3: Polymerization of fiber composite gel emulsion

[0038] The mold containing the fiber composite gel emulsion in Step 2 was sealed, reacted in a water bath at 80°C for 6 h and then demolded, and dried to constant weight in an oven at 80°C to obtain a fiber composite lightweight and high-strength crosslinked polystyrene foam with a density of 0.27±0.01 g / cm 3 . The complete drying time of the foam with actual dimensions of 1600 mm×800 mm×30 mm is about 19 days, the flexural strength is about 12.5 MPa, the flexural modulus is about 430 MPa, and the notched impact strength is about 1.4 kJ / m 2 . Example 2

[0039] Step 1: Preparation of gel emulsion soft template

[0040] At normal temperature and pressure, 12.75 g of iron oxide nanoparticles, 1084 mL of styrene, 127.5 mL of triallyl isocyanurate, 63.75 mL of ethylene glycol dimethacrylate, and 38.2 g of benzoyl peroxide were added to a beaker and mixed evenly with an emulsifier to form a continuous phase; then 2474 mL of water was added to the continuous phase while emulsifying until a uniform, delicate, milky white gel emulsion that did not flow when inverted was formed.

[0041] Step 2: Preparation of fiber composite gel emulsion

[0042] Using the impregnation method, the gel emulsion from Step 1 was compounded with alkali-free glass fiber filaments with a monofilament diameter of 10 - 30 μm in a mold with dimensions of 502 mm×502 mm×40 mm. The addition amount of the alkali-free glass fiber filaments was 40% of the mass of the continuous phase in the gel emulsion to obtain a fiber composite gel emulsion.

[0043] Step 3: Polymerization of fiber composite gel emulsion

[0044] Seal the mold containing the fiber composite gel emulsion in Step 2, demold it after reacting in a water bath at 50 °C for 8 h, and dry it to a constant weight in a constant temperature oven at 80 °C to obtain a fiber composite lightweight and high-strength crosslinked polystyrene foam with a dry density of 0.55 ± 0.01 g / cm 3 The completely dry time of the foam with an actual size of 500 mm × 500 mm × 15 mm is about 12 days, the flexural strength is about 60 MPa, the flexural modulus is about 2.2 GPa, and the notched impact strength is about 36.4 kJ / m 2 . Example 3

[0045] Step 1: Preparation of the gel emulsion soft template

[0046] Under normal temperature and pressure, add 12.75 g of silica micro-nano particles, 1084 mL of styrene, 127.5 mL of triallyl isocyanurate, 63.75 mL of ethylene glycol dimethacrylate, and 38.2 g of benzoyl peroxide into a beaker and mix them evenly with an emulsifier to form a continuous phase; then add 2474 mL of water to the continuous phase while emulsifying until a uniform, delicate, and non-flowing inverted milky white gel emulsion is formed.

[0047] Step 2: Preparation of the fiber composite gel emulsion

[0048] Using the layer laying method, compound the gel emulsion in Step 1 with an alkali-free glass fiber mat with a model of 100 g / m 2 in a mold with dimensions of 502 mm × 502 mm × 40 mm. The addition amount of the alkali-free glass fiber mat is 40% of the mass of the continuous phase in the gel emulsion to obtain a fiber composite gel emulsion.

[0049] Step 3: Polymerization of the fiber composite gel emulsion

[0050] Seal the mold containing the fiber composite gel emulsion in Step 2, demold it after reacting in a water bath at 50 °C for 8 h, and dry it to a constant weight in a constant temperature oven at 80 °C to obtain a fiber composite lightweight and high-strength crosslinked polystyrene foam with a dry density of 0.55 ± 0.01 g / cm 3 The completely dry time of the foam with an actual size of 500 mm × 500 mm × 15 mm is about 13 days, the flexural strength is about 44 MPa, the flexural modulus is about 1.7 GPa, and the notched impact strength is about 35 kJ / m 2 . Example 4

[0051] Step 1: Preparation of the gel emulsion soft template

[0052] Under normal temperature and pressure, 12.75 g of silicon dioxide micro-nano particles, 1084 mL of styrene, 127.5 mL of triallyl isocyanurate, 63.75 mL of ethylene glycol dimethacrylate and 38.2 g of benzoyl peroxide were added to a beaker and mixed evenly with an emulsifier to form a continuous phase; then 2474 mL of water was added to the continuous phase while emulsifying until a uniform, delicate, milky white gel emulsion that did not flow when inverted was formed.

[0053] Step 2: Preparation of fiber composite gel emulsion

[0054] Using the layer laying method, the gel emulsion from Step 1 was compounded with an alkali-free glass fiber mat with a model of 100 g / m 2 in a mold with dimensions of 502 mm × 502 mm × 40 mm. The addition amount of the alkali-free glass fiber mat was 60% of the mass of the continuous phase in the gel emulsion to obtain a fiber composite gel emulsion.

[0055] Step 3: Polymerization of fiber composite gel emulsion

[0056] The mold containing the fiber composite gel emulsion from Step 2 was sealed, reacted in a water bath at 50 °C for 8 h and then demolded, and dried to constant weight in a constant temperature oven at 80 °C to obtain a fiber composite lightweight and high-strength crosslinked polystyrene foam with a dry density of 0.66 ± 0.01 g / cm 3 The complete drying time of the foam with actual dimensions of 500 mm × 500 mm × 15 mm was about 4 days, the flexural strength was about 69 MPa, the flexural modulus was about 4.4 GPa, and the notched impact strength was about 46 kJ / m 2 . Example 5

[0057] Step 1: Preparation of gel emulsion soft template

[0058] Under normal temperature and pressure, 70 g of titanium dioxide micro-nano particles, 1.4 g of sodium dodecyl sulfate, 995.7 mL of acrylonitrile, 110.6 mL of methyl methacrylate, 14 mL of triallyl isocyanurate, 280 mL of ethylene glycol dimethacrylate and 28 g of diisopropyl peroxydicarbonate were added to a beaker and mixed evenly with an emulsifier to form a continuous phase; then 1949 mL of water was added to the continuous phase while emulsifying until a uniform, delicate, milky white gel emulsion that did not flow when inverted was formed.

[0059] Step 2: Preparation of fiber composite gel emulsion

[0060] Using the casting method, the gel emulsion from Step 1 is compounded with an alkali-free glass fiber three-dimensional framework in a mold with dimensions of 502 mm × 502 mm × 40 mm. The addition amount of the alkali-free glass fiber three-dimensional framework is 35% of the mass of the continuous phase in the gel emulsion, obtaining a fiber composite gel emulsion.

[0061] Step 3: Polymerization of the fiber composite gel emulsion

[0062] Seal the mold containing the fiber composite gel emulsion from Step 2, react in a 40°C water bath for 5 h, then react at 120°C for 12 h and demold. After demolding, place the material in an 80°C constant temperature oven and dry to constant weight, obtaining a fiber composite lightweight and high-strength crosslinked polymer foam with a dry density of 0.67 ± 0.01 g / cm 3 The completely dry time for a foam with actual dimensions of 500 mm × 500 mm × 15 mm is about 18 days, the flexural strength is about 65 MPa, the flexural modulus is about 2.0 GPa, and the notched impact strength is about 34 kJ / m 2 . Example 6

[0063] Step 1: Preparation of the gel emulsion soft template

[0064] Under normal temperature and pressure, add 70 g of titanium dioxide micro-nano particles, 1.4 g of sodium dodecyl sulfonate, 995.7 mL of styrene, 110.6 mL of methyl methacrylate, 14 mL of triallyl isocyanurate, 280 mL of ethylene glycol dimethacrylate, and 28 g of diisopropyl peroxydicarbonate to a beaker and mix evenly with an emulsifier to form a continuous phase; then add 1949 mL of water to the continuous phase while emulsifying until a uniform, delicate, and non-flowing inverted milky white gel emulsion is formed.

[0065] Step 2: Preparation of the fiber composite gel emulsion

[0066] Using the casting method, the gel emulsion from Step 1 is compounded with an alkali-free glass fiber three-dimensional framework in a mold with dimensions of 502 mm × 502mm × 40 mm. The addition amount of the alkali-free glass fiber three-dimensional framework is 60% of the mass of the continuous phase in the gel emulsion, obtaining a fiber composite gel emulsion.

[0067] Step 3: Polymerization of the fiber composite gel emulsion

[0068] Seal the mold containing the fiber composite gel emulsion from Step 2, react in a 40°C water bath for 5 h, then react at 120°C for 12 h and demold. After demolding, place the material in an 80°C constant temperature oven and dry to constant weight, obtaining a fiber composite lightweight and high-strength crosslinked polymer foam with a dry density of 0.79 ± 0.01 g / cm 3Fiber-reinforced lightweight and high-strength crosslinked polystyrene foam. The complete drying time of a foam with actual dimensions of 500 mm × 500 mm × 15 mm is about 8 days, the flexural strength is about 76 MPa, the flexural modulus is about 4.54 GPa, and the notched impact strength is about 59 kJ / m 2 . Example 7

[0069] Step 1: Preparation of gel emulsion soft template

[0070] At normal temperature and pressure, 28.2 g of iron oxide nanoparticles, 2.82 g of sodium dibutylnaphthalenesulfonate, 986.4 mL of tert-butyl methacrylate, 422.7 mL of trimethylolpropane trimethacrylate, and 14.1 g of cumene hydroperoxide were added to a beaker and mixed evenly with an emulsifier to form a continuous phase; then 1276 mL of water was added to the continuous phase while emulsifying until a uniform, delicate, and non-flowing inverted milky white gel emulsion was formed.

[0071] Step 2: Preparation of fiber-reinforced gel emulsion

[0072] Using the impregnation method, the gel emulsion from Step 1 was compounded with 1313 aramid fiber filaments with a monofilament diameter of 10 - 20 μm in a mold with dimensions of 502 mm × 502 mm × 40 mm. The addition amount of the 1313 aramid fiber filaments was 40% of the mass of the continuous phase in the gel emulsion, and the laying direction of the fiber filaments was 0°. A fiber-reinforced gel emulsion was obtained.

[0073] Step 3: Polymerization of fiber-reinforced gel emulsion

[0074] The mold containing the fiber-reinforced gel emulsion from Step 2 was sealed and reacted in a 30°C water bath for 10 h, then reacted at 140°C for 6 h and demolded. After demolding, the material was placed in an 80°C constant temperature oven and dried to a constant weight to obtain a fiber-reinforced lightweight and high-strength crosslinked polymer foam with a dry density of 0.62 ± 0.01 g / cm 3 The complete drying time of a foam with actual dimensions of 500 mm × 500 mm × 15 mm is about 15.5 days, the flexural strength is about 61 MPa, the flexural modulus is about 2.3 GPa, and the notched impact strength is about 47 kJ / m 2 . Example 8

[0075] Step 1: Preparation of gel emulsion soft template

[0076] At normal temperature and pressure, 28.2 g of iron oxide nanoparticles, 2.82 g of sodium dibutylnaphthalenesulfonate, 690.5 mL of styrene, 295.9 mL of acrylonitrile, 422.7 mL of trimethylolpropane trimethacrylate, and 14.1 g of cumene hydroperoxide were added to a beaker and mixed evenly with an emulsifier to form a continuous phase. Then, 1275 mL of water was added to the continuous phase while emulsifying until a uniform, delicate, and non-flowing inverted milky white gel emulsion was formed.

[0077] Step 2: Preparation of fiber composite gel emulsion

[0078] Using the impregnation method, the gel emulsion from Step 1 was compounded with 1313 aramid fiber filaments with a monofilament diameter of 10 - 20 μm in a mold with dimensions of 502 mm × 502 mm × 40 mm. The addition amount of the 1313 aramid fiber filaments was 10% of the mass of the continuous phase in the gel emulsion, and the fiber filaments were laid alternately in the 0° and 90° directions to obtain a fiber composite gel emulsion.

[0079] Step 3: Polymerization of fiber composite gel emulsion

[0080] The mold containing the fiber composite gel emulsion from Step 2 was sealed and reacted in a water bath at 30°C for 10 h, then reacted at 140°C for 6 h and demolded. After demolding, the material was placed in an oven at 80°C and dried to a constant weight to obtain a fiber composite cross-linked polystyrene foam with a dry density of 0.55 ± 0.01 g / cm 3 . The complete drying time of the foam with actual dimensions of 500 mm × 500 mm × 15 mm was about 26 days, the flexural strength was about 36 MPa, the flexural modulus was about 1.7 GPa, and the notched impact strength was about 23 kJ / m 2 . Example 9

[0081] Step 1: Preparation of gel emulsion soft template

[0082] At normal temperature and pressure, 140.9 g of zinc oxide nanoparticles, 1972.9 mL of styrene, 854.52 mL of trimethylolpropane trimethacrylate, and 28.2 g of cumene hydroperoxide were added to a beaker and mixed evenly with an emulsifier to form a continuous phase. Then, 329 mL of water was added to the continuous phase while emulsifying until a uniform, delicate, and non-flowing inverted milky white gel emulsion was formed.

[0083] Step 2: Preparation of fiber composite gel emulsion

[0084] Using the layer laying method, the gel emulsion from Step 1 was compounded with a model of 80 g / m 2The 1414 aramid fiber woven fabric is compounded in a mold with dimensions of 502 mm×502 mm×40 mm. The addition amount of the 1414 aramid fiber woven fabric is 20% of the mass of the continuous phase in the gel emulsion, and a fiber composite gel emulsion is obtained.

[0085] Step 3: Polymerization of the fiber composite gel emulsion

[0086] Seal the mold containing the fiber composite gel emulsion in Step 2, react in a water bath at 30°C for 10 h, then react at 140°C for 6 h and demold. After demolding, place the material in an oven at 80°C and dry it to a constant weight to obtain a fiber composite cross-linked polystyrene foam with a dry density of 0.98±0.01 g / cm 3 The completely dry time of the foam with actual dimensions of 500 mm×500 mm×15 mm is about 13 days, the flexural strength is about 95 MPa, the flexural modulus is about 3.5 GPa, and the notched impact strength is about 70 kJ / m 2 . Example 10

[0087] Step 1: Preparation of the gel emulsion soft template

[0088] Under normal temperature and pressure, add 4.5 g of cholesterol derivative, 540 mL of styrene, 360 mL of ethylene glycol dimethacrylate, and 27 g of azobisisobutyronitrile to a beaker and mix them evenly with an emulsifier to form a continuous phase; then add 2700 mL of water to the continuous phase while emulsifying until a uniform, delicate, and non-flowing inverted milky white gel emulsion is formed.

[0089] Step 2: Preparation of the fiber composite gel emulsion

[0090] Adopt the layer paving method to compound the gel emulsion in Step 1 with carbon fiber filaments with a monofilament diameter of 10 - 20 μm in a mold with dimensions of 502 mm×502 mm×40 mm. The addition amount of the carbon fiber filaments is 5% of the mass of the continuous phase in the gel emulsion, and the laying directions of the fiber filaments are alternately laid at 0° and 45°, and a fiber composite gel emulsion is obtained.

[0091] Step 3: Polymerization of the fiber composite gel emulsion

[0092] Seal the mold containing the fiber composite gel emulsion in Step 2, react in a water bath at 80°C for 10 h and then demold. After demolding, place the material in an oven at 80°C and dry it to a constant weight to obtain a fiber composite cross-linked polystyrene foam with a dry density of 0.26 g / cm 3Fiber composite cross-linked polystyrene foam. The complete drying time of the foam with an actual size of 500 mm × 500 mm × 15 mm is about 6 days, the flexural strength is about 11.5 MPa, the flexural modulus is about 415 MPa, and the notched impact strength is about 2.0 kJ / m 2 . Example 11

[0093] Step 1: Preparation of gel emulsion soft template

[0094] At normal temperature and pressure, 73.5 g of silica micro-nano particles, 24.5 g of sodium dibutylnaphthalenesulfonate, 1960 mL of styrene, 245 mL of trimethylolpropane trimethacrylate, 245 mL of hexanediol diacrylate, and 12.25 g of tert-butyl peroxybenzoate were added to a beaker and mixed evenly with an emulsifier to form a continuous phase; then 1092 mL of water was added to the continuous phase while emulsifying until a uniform, delicate, and non-flowing inverted milky white gel emulsion was formed.

[0095] Step 2: Preparation of fiber composite gel emulsion

[0096] Using the layer laying method, the gel emulsion from Step 1 was compounded with a carbon fiber felt with a model of 100 g / m 2 in a mold with dimensions of 502 mm × 502 mm × 40 mm. The addition amount of the carbon fiber felt was 10% of the mass of the continuous phase in the gel emulsion to obtain a fiber composite gel emulsion.

[0097] Step 3: Polymerization of fiber composite gel emulsion

[0098] The mold containing the fiber composite gel emulsion from Step 2 was sealed and reacted in a 35°C water bath for 10 h, then reacted at 140°C for 6 h and demolded. After demolding, the material was placed in an 80°C constant temperature oven and dried to a constant weight to obtain a fiber composite cross-linked polystyrene foam with a dry density of 0.76 ± 0.01 g / cm 3 The complete drying time of the foam with an actual size of 500 mm × 500 mm × 15mm is about 29 days, the flexural strength is about 66 MPa, the flexural modulus is about 2.05 GPa, and the notched impact strength is about 19 kJ / m 2 . Example 12

[0099] Step 1: Preparation of gel emulsion soft template

[0100] Under normal temperature and pressure, 73.5 g of silicon dioxide micro-nano particles, 40 g of sodium dodecyl sulfate, 1600 mL of styrene, 200 mL of trimethylolpropane trimethacrylate, 200 mL of hexanediol diacrylate, and 10 g of azodiisobutyronitrile were added to a beaker and mixed evenly with an emulsifier to form a continuous phase; then, while emulsifying, 1874 mL of water was added to the continuous phase until a uniform, delicate, and non-flowing inverted milky white gel emulsion was formed.

[0101] Step 2: Preparation of fiber composite gel emulsion

[0102] Using the impregnation method, the gel emulsion from Step 1 was compounded with carbon fiber filaments with a monofilament diameter of 10 - 20 μm in a mold with dimensions of 502 mm × 502 mm × 40 mm. The addition amount of the carbon fiber filaments was 30% of the mass of the continuous phase in the gel emulsion, and the fiber filaments were laid alternately in the 0° and 90° directions to obtain a fiber composite gel emulsion.

[0103] Step 3: Polymerization of fiber composite gel emulsion

[0104] The mold containing the fiber composite gel emulsion from Step 2 was sealed and reacted in a water bath at 60°C for 10 h, then demolded. After demolding, the material was placed in an oven at 80°C and dried to a constant weight to obtain a fiber composite cross-linked polystyrene foam with a dry density of 0.65 ± 0.01 g / cm 3 The foam with actual dimensions of 500 mm × 500 mm × 15 mm took about 19.5 days to completely dry, had a flexural strength of about 57 MPa, a flexural modulus of about 3.5 GPa, and a notched impact strength of about 41 kJ / m 2 .

[0105] Comparative Example 1

[0106] 3.4 g of titanium dioxide micro-nano particles, 289 mL of styrene, 34 mL of triallyl isocyanurate, 17 mL of ethylene glycol dimethacrylate, and 10 g of benzoyl peroxide were added to a beaker and mixed evenly with an emulsifier. While emulsifying, 660 mL of water was added to the mixed oil phase, and finally a uniform and delicate, non-flowing inverted gel emulsion was formed. The gel emulsion was poured into a mold with dimensions of 502×502×40 mm, and the sealed mold was reacted in a water bath at 50 o °C for 8 h to obtain a cross-linked styrene foam with a dry density of 0.34 ± 0.01 g / cm 3 The cross-linked polystyrene foam with actual dimensions of 500×500×15 mm took about 24 days to completely dry in an 80°C oven, had a flexural strength of 12 MPa, a flexural modulus of 490 MPa, and a notched impact strength of 1.0 kJ / m2 。

[0107] Comparative Example 2

[0108] In Step 2 of Example 1, no glass fiber filaments were added, and the other steps were the same as those in Example 1, obtaining a cross-linked polystyrene foam with a density of 0.25 ± 0.01 g / cm 3 . The completely drying time of the foam with an actual size of 1600 mm × 800 mm × 30 mm was about 22 days, the flexural strength was about 6.5 MPa, the flexural modulus was about 290 MPa, and the notched impact strength was about 0.6 kJ / m 2 。

[0109] Comparative Example 3

[0110] 22 g of Fe₃O₄ micro-nano particles, 1870 mL of styrene, 220 mL of triallyl isocyanurate, 110 mL of ethylene glycol dimethacrylate, and 66 g of benzoyl peroxide were added to a beaker and mixed evenly with an emulsifier. While emulsifying, 1800 mL of water was added to the mixed oil phase. Finally, a uniform, delicate, and non-flowing inverted gel emulsion was formed. The prepared gel emulsion was poured into a predetermined mold and sealed. After reacting in a 50°C water bath for 8 h, it was demolded and dried to a constant weight in an 80°C constant-temperature oven to obtain a cross-linked polystyrene foam with a dry density of 0.55 ± 0.01 g / cm 3 . The completely drying time of the cross-linked polystyrene foam with an actual size of 500×500×15 mm was about 43 days, the flexural strength was about 30 MPa, the flexural modulus was about 1.1 GPa, and the notched impact strength was about 4.1 kJ / m 2 。

[0111] Comparative Example 4

[0112] 75 g of SiO₂ micro-nano particles, 2000 mL of styrene, 250 mL of trimethylolpropane trimethacrylate, 250 mL of ethylene glycol dimethacrylate, and 12.5 g of azobisisoheptonitrile were added to a beaker and mixed evenly with an emulsifier. While emulsifying, 1386 mL of water was added to the mixed oil phase. Finally, a uniform, delicate, and non-flowing inverted gel emulsion was formed. The prepared gel emulsion was poured into a predetermined mold and sealed. After reacting in a 50°C water bath for 8 h, it was demolded and dried to a constant weight in an 80°C constant-temperature oven, obtaining a cross-linked polystyrene foam with a dry density of 0.65 ± 0.01 g / cm 3 . The completely drying time of the cross-linked polystyrene foam with an actual size of 500×500×15 mm was about 72 days, the flexural strength was about 37 MPa, the flexural modulus was about 1.3 GPa, and the notched impact strength was about 4.9 kJ / m2 。

[0113] As can be seen from Figure 1 、 2 and 3, the fiber composite cross-linked polystyrene foam in the present invention has regular appearance and smooth surface.

[0114] As can be seen from Figure 5 and Figure 6 : In the fiber composite cross-linked polystyrene foam of Example 4, the fibers cross through the dispersed phase and the continuous phase, and there is a gap of about 60 nm between the fibers and the continuous phase, providing a channel for the "mass transfer" process in the drying of the dispersed phase moisture (the size of water molecules is about 0.4 nm), and accelerating the drying rate. As can be seen from Figure 7 : There is a gap of about 15 nm between the fibers and the continuous phase of the cross-linked polystyrene foam in Example 9. As can be seen from Figure 8 : It can be seen that the interfacial adhesion between the fibers and the polymer foam in Example 12 is good. Therefore, while the drying speed of the foam material of the present invention is accelerated, the mechanical properties are also significantly improved.

[0115] As can be seen from Figure 9 the drying curve trends of the three materials of Example 3, Example 4 and Comparative Example 1: After introducing the fibers, the dry density of the material increases and the drying rate of the material accelerates. As can be seen from Figure 10 and Figure 11 : It can be concluded that on the premise of the same dry density, the drying rate of the material prepared by using the fiber composite gel emulsion is significantly improved.

[0116] It can be seen from Figure 10 and Figure 12 that the actual densities of the materials in Example 2 and Comparative Example 3 are both about 0.55 g / cm 3 , but the drying time of the material in Example 2 is shortened by nearly 2.6 times compared with that of the material in Comparative Example 3, the flexural strength and flexural modulus are increased by about 1 time compared with those of the material in Comparative Example 3, and the notched impact strength is increased by nearly 8 times compared with that of the material in Comparative Example 3. It can be seen from Figure 11 and Figure 13 that the actual densities of the materials in Example 12 and Comparative Example 4 are both about 0.65 g / cm 3 , but the drying time of the material in Example 12 is shortened by nearly 2.7 times compared with that of the material in Comparative Example 4, the flexural strength is increased by about 0.55 times compared with that of the material in Comparative Example 4, the flexural modulus is increased by nearly 1.7 times compared with that of the material in Comparative Example 4, and the notched impact strength is increased by nearly 7.4 times compared with that of the material in Comparative Example 4. Therefore, generally speaking, the drying rate of the fiber composite cross-linked polystyrene foam material prepared by using the fiber composite gel emulsion is significantly faster than that of the cross-linked polystyrene foam, and the flexural performance and impact performance are significantly increased.

Claims

1. A preparation method of a fiber composite lightweight and high-strength crosslinked polymer foam, characterized in that, It includes the following steps: Step 1: Preparation of a gel emulsion soft template Under normal temperature and pressure, a gelling agent, a reaction monomer, a crosslinking agent, and an initiator are stirred evenly to form a continuous phase; then a dispersion phase is added to the continuous phase for emulsification to form a uniform, delicate, and non-flowing inverted gel emulsion; wherein, the gelling agent is any one or a combination of cholesterol derivatives, iron tetroxide micro-nano particles, titanium dioxide micro-nano particles, silicon dioxide micro-nano particles, zinc oxide micro-nano particles, or the gelling agent is any one or a combination of cholesterol derivatives, iron tetroxide micro-nano particles, titanium dioxide micro-nano particles, silicon dioxide micro-nano particles, zinc oxide micro-nano particles and any one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, and sodium dibutylnaphthalene sulfonate; the reaction monomer is any one or a mixture of styrene, acrylonitrile, methyl methacrylate, and tert-butyl methacrylate; the dispersion phase accounts for 10% - 75% of the total mass of the dispersion phase and the continuous phase; the dispersion phase is any one of water, inorganic salt solution, acid solution, and alkali solution that does not react with and is immiscible with the continuous phase; Step 2: Preparation of a fiber composite gel emulsion The gel emulsion in Step 1 is compounded with fibers treated with a silanizing agent to obtain a fiber composite gel emulsion; wherein, the addition amount of the fibers treated with the silanizing agent is 5% - 60% of the total mass of the continuous phase in the gel emulsion; the fibers are any one of glass fibers, carbon fibers, and aramid fibers, and the fiber structure is any one of fiber filaments, fiber felts, fiber cloths, and fiber three-dimensional frameworks; when the fibers are fiber filaments, fiber felts, or fiber cloths, the compounding method is layer laying compounding, casting compounding, or impregnation compounding; when the fibers are fiber three-dimensional frameworks, the compounding method is casting compounding; Step 3: Polymerization of the fiber composite gel emulsion The mold filled with the fiber composite gel emulsion is placed in a water bath or an oven for initiation polymerization. After the reaction is completed, demolding is carried out, and the demolded sample block is dried to a constant weight to obtain a fiber composite lightweight and high-strength crosslinked polymer foam.

2. The preparation method of the fiber composite lightweight and high-strength crosslinked polymer foam according to claim 1, characterized in that, In Step 1, when the reaction monomer is a mixture of styrene and acrylonitrile or methyl methacrylate or tert-butyl methacrylate, the addition amount of acrylonitrile or methyl methacrylate or tert-butyl methacrylate is 10% - 40% of the volume of styrene.

3. The preparation method of the fiber composite lightweight and high-strength crosslinked polymer foam according to claim 1, characterized in that, In Step 1, the crosslinking agent is any one or a combination of a difunctional crosslinking agent and a trifunctional crosslinking agent. The difunctional crosslinking agent is any one or a mixture of ethylene glycol dimethacrylate and hexanediol diacrylate, and the trifunctional crosslinking agent is any one or a mixture of triallyl isocyanurate and trimethylolpropane trimethacrylate; the initiator is any one or a mixture of azobisisobutyronitrile, azobisisoheptonitrile, benzoyl peroxide, cumene hydroperoxide, diisopropyl peroxydicarbonate, and tert-butyl peroxybenzoate.

4. The preparation method of the fiber composite lightweight and high-strength crosslinked polymer foam according to claim 1, wherein, In Step 1, the addition amount of the gelling agent is 0.5% to 5% of the total mass of the reaction monomer and the crosslinking agent; the total addition amount of the crosslinking agent is 10% to 50% of the total mass of the reaction monomer and the crosslinking agent, wherein the addition amount of the difunctional crosslinking agent is 5% to 40% of the total mass of the reaction monomer and the crosslinking agent, and the addition amount of the trifunctional crosslinking agent is 1% to 30% of the total mass of the reaction monomer and the crosslinking agent; the addition amount of the initiator is 0.5% to 3% of the total mass of the reaction monomer and the crosslinking agent.

5. The preparation method of the fiber composite lightweight and high-strength crosslinked polymer foam according to claim 1, characterized in that, In Step 2, the silanization reagent is any one or a mixture of more than one of KH550, KH560, and KH570.

6. The preparation method of the fiber composite lightweight and high-strength crosslinked polymer foam according to claim 1, characterized in that, In Step 3, when the initiator is azobisisobutyronitrile, azobisisoheptonitrile, or dibenzoyl peroxide, the temperature for initiating polymerization is 30 to 90 °C, and the reaction time is 4 to 12 h; when the initiator is cumene hydroperoxide, diisopropyl peroxydicarbonate, or tert-butyl peroxybenzoate, the process of initiating polymerization is as follows: first pre-polymerize at 30 to 80 °C for 4 to 10 h, and then continue to react at 90 to 150 °C for 6 to 12 h.

7. A fiber composite lightweight and high-strength crosslinked polymer foam prepared by the method according to any one of claims 1 to 6.

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