Renewable phenolic resin for ablative composite material and preparation method thereof
By introducing a dynamic covalent cross-linked network to prepare phenolic resin, the problems of thermal performance and renewability of phenolic resin in ablation composites have been solved, achieving high efficiency in ablation resistance and recyclability, which is suitable for the aerospace field.
Patent Information
- Application Number
- CN202511415577.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-30
- Publication Date
- 2025-12-12
AI Technical Summary
The thermal properties of existing phenolic resins cannot meet the requirements of ablation composites, and modification strategies are difficult to balance ablation resistance, mechanical properties and renewability, resulting in materials that are prone to cracking and peeling under extreme high temperature environments. In addition, traditional modification methods have problems such as complex processes, high costs and non-renewability.
Renewable phenolic resin for ablation composites can be prepared by a one-pot or two-step method. Amino silicone oil and aromatic boric acid compounds are introduced to form a dynamic covalent cross-linked network. The reaction process does not require a catalyst, and a reversible cross-linked structure is constructed to achieve the renewability and excellent thermal properties of the material.
It improves the ablation resistance and thermal stability of phenolic resin, allows the material to be recycled multiple times, reduces resource consumption and environmental pollution, improves mechanical properties, and is suitable for large-scale production.
Smart Images
Figure CN121108495A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to resin matrices and their preparation methods, specifically to a renewable phenolic resin for ablation composite materials and its preparation method. Background Technology
[0002] When a spacecraft enters the atmosphere, aerodynamic heating causes temperatures exceeding 1000°C on its surface, leading to physical and chemical reactions that severely damage the aircraft. The emergence of ablative composite materials ensures that spacecraft can maintain their integrity and operate normally under extreme conditions such as high enthalpy and high heat flux. By covering the surface of the aircraft, these composites dissipate heat through their own ablation, thus protecting the aircraft. Therefore, ablative composite materials are of great significance to the development of aerospace. Based on different ablation mechanisms, ablative materials can be classified into sublimation, melting, and carbonization types. Fiber / phenolic resin-based composite materials belong to the carbonization type of ablative material. Due to their good processability, low cost, high quality stability, and moderate heat resistance and ablation resistance, they are widely used in the manufacture of heat-resistant and ablation-resistant components. The performance of ablation materials depends to some extent on the resin matrix. However, with the development of the aerospace field, the thermal properties of existing phenolic resins can no longer meet the requirements of ablation composite materials. Moreover, once cured, they are difficult to reprocess, resulting in huge waste of resources and environmental pollution. The development of renewable resin matrices for ablation composite materials is a hot topic in the field of thermal protection materials.
[0003] Currently, there are two main types of modification methods to improve the thermal properties of phenolic resins: one is to introduce other elements or functional components into the molecular structure of phenolic resins, such as metal elements (molybdenum, tungsten), heteroatoms (boron, silicon), or elastomers (such as rubber components), to enhance their heat resistance or toughness; the other is to modify the structure of phenolic resins by introducing aromatic groups (such as phenyl) to improve their aromaticity and thermal stability. While these methods have improved the high-temperature resistance of phenolic resins to some extent, they generally suffer from complex processes, high costs, and the possibility that the introduced components may lead to poor compatibility or structural decomposition at high temperatures. Furthermore, some modifiers are non-renewable, making it difficult to meet the needs of green and sustainable development. In addition, the traditional curing process of phenolic resins usually relies on acidic catalysts, which not only poses risks of equipment corrosion and environmental pollution but may also affect the purity and stability of the final material. More importantly, existing modification strategies often fail to balance the material's ablation resistance, mechanical properties, and renewability. Especially under extreme high-temperature ablation environments, the material is prone to defects such as cracking, peeling, and loose carbon layer structure, limiting its long-term reliable application in high-end fields such as aerospace. Summary of the Invention
[0004] The purpose of this invention is to provide a renewable phenolic resin for ablation composite materials and its preparation method. The reaction process does not require the addition of a catalyst, the process is simple, it can improve the ablation resistance of phenolic resin, improve the brittleness of phenolic resin, and take into account the recyclability of the material.
[0005] This invention is achieved through the following technical solution:
[0006] A method for preparing renewable phenolic resin for ablation composite materials, comprising a one-pot process and the following steps:
[0007] Step 1: Dissolve 100 parts by weight of thermoplastic phenolic resin in a low-boiling-point polar organic solvent to obtain solution A.
[0008] Step 2: Dissolve 15-30 parts by mass of monoaldehyde aromatic boric acid compound or 30-60 parts by mass of dialdehyde arylboronic acid compound in a low-boiling-point polar organic solvent to obtain solution B.
[0009] Step 3: Weigh out amino silicone oil with a molar ratio of amino (-NH2) to aldehyde (-CHO) of 1:1 and dissolve it in a low-boiling-point polar organic solvent to obtain solution C;
[0010] Step 4: Mix solutions A, B, and C and stir at room temperature until a homogeneous solution is formed. After removing about 80% of the solvent by rotary evaporation, vacuum cure at 180°C for 10 hours to obtain a renewable phenolic resin for ablation composite materials.
[0011] A method for preparing a renewable phenolic resin for ablation composite materials, comprising a two-step process and the following steps:
[0012] Step 1: Dissolve 15-30 parts by mass of a monoaldehyde aromatic boric acid compound or 30-60 parts by mass of a dialdehyde arylboronic acid compound in a low-boiling-point organic solvent to obtain solution A.
[0013] Step 2: Weigh out a measured amount of amino silicone oil with a molar ratio of n(-NH2):n(-CHO) = 1:1, dissolve it in a low-boiling-point organic solvent, and use it as solution B.
[0014] Step 3: Mix solutions A and B and stir for 4-6 hours. After removing about 80% of the solvent by rotary evaporation, dry under vacuum at 60°C for 6-10 hours to obtain an intermediate containing an imine bond for later use.
[0015] Step 4: By mass, 100 parts of thermoplastic phenolic resin and the imine-containing intermediate synthesized in step 3 are dissolved together in a low-boiling-point organic solvent. The mixture is stirred at room temperature until a homogeneous solution is formed. After removing about 80% of the solvent by rotary evaporation, the mixture is vacuum cured at 180°C for 10 hours to obtain a regenerable phenolic resin for ablation composite materials.
[0016] Furthermore, the phenolic resin is one or more of the following in any proportion: high ortho-position thermoplastic phenolic resin, atactic thermoplastic phenolic resin, bisphenol A type thermoplastic phenolic resin, bisphenol F type thermoplastic phenolic resin, catechol type thermoplastic phenolic resin, naphthol type thermoplastic phenolic resin, and cashew phenol-based thermoplastic phenolic resin.
[0017] Furthermore, the monoaldehyde aromatic boric acid compound is one of 2-formylphenylboronic acid (2-PBA), 3-formylphenylboronic acid (3-PBA), or 4-formylphenylboronic acid (4-PBA); the dialdehyde aromatic boric acid compound is 3,5-diformylphenylboronic acid (3,5-PBA).
[0018] Furthermore, the amino silicone oil is an amino-terminated polydimethylsiloxane.
[0019] Furthermore, the low-boiling-point polar organic solvent is one or more of acetone, ethanol, and tetrahydrofuran mixed in any proportion.
[0020] This invention also provides a renewable phenolic resin for ablation composite materials, wherein in the renewable phenolic resin for ablation composite materials, an aldehyde-based aromatic boric acid compound reacts with the hydroxyl groups of the phenolic resin and the amino groups of polydimethylsiloxane to form a polymeric cross-linked network containing dynamic covalent bonds; the thermal decomposition temperature (T) of the renewable phenolic resin is... 10％ The maximum temperature can reach 396.2℃, and the char yield can reach up to 62.0%.
[0021] Compared with the prior art, the present invention has the following beneficial effects:
[0022] The renewable phenolic resin of this invention can be prepared by a one-pot or two-step method. The one-pot method is simple and easy to operate, suitable for large-scale preparation; the two-step method makes it easier to characterize the successful preparation of intermediates. First, amino silicone oil and aldehyde-based aromatic borate compounds undergo a condensation reaction to generate an intermediate containing dynamic imine bonds and borate ester groups. Subsequently, this intermediate reacts further with thermoplastic phenolic resin to construct a resin system with a reversible crosslinking network. Using aryl borate compounds with aldehyde functional groups as co-crosslinking agents, they undergo condensation reactions with the hydroxyl groups of the phenolic resin and the amino groups of the amino silicone oil, respectively, to jointly form a dense three-dimensional crosslinking network. The introduced high-bond-energy siloxane bonds give the phenolic resin a high thermal decomposition temperature; the dynamic borate ester and imine bonds allow for repeated processing and reuse, and the reaction process requires no catalyst, resulting in a simple process flow. The obtained polymer material exhibits excellent thermal properties and recyclability.
[0023] This invention introduces dynamic borate ester bonds and imine bonds as reversible crosslinking points in the crosslinking network. Under external stimuli (such as heating or acidic conditions), the dynamic covalent bonds can break, achieving dissociation of the network structure. When the stimulus is removed, the bonded structure can spontaneously reclose and reorganize, thus endowing the material with good reprocessability and remodeling properties. This strategy overcomes the limitations of traditional thermosetting phenolic resins, which are permanently crosslinked and non-recyclable, enabling multiple recycling of polymer materials and significantly reducing resource consumption and negative environmental impact.
[0024] The amino silicone oil introduced in this invention has high bond energy Si-O (460 kJ / mol) bonds, which is much higher than the bond energy of C-C bonds (350 kJ / mol), enabling the modified phenolic resin to maintain a high char residue while also having a high thermal decomposition temperature. Furthermore, the silicone oil segments are flexible, which can overcome the brittleness and poor mechanical properties of phenolic resins caused by their excessively high crosslinking density.
[0025] This invention controls the crosslinking density of polymer materials by changing the content of arylboronic acid compounds, thereby adjusting the thermal and mechanical properties of the polymer materials to meet the requirements of ablation-resistant materials in different environments. Attached Figure Description
[0026] Figure 1 PDMS, the intermediate prepared in Example 13 248.52 / 4-PBA 15 The 1H NMR spectrum under acidic conditions;
[0027] Figure 2 PDMS, the intermediate prepared in Example 13 248.52 / 4-PBA 15 The proton and carbon NMR spectra, among which Figure 2 (a) is PDMS248.52 / 4-PBA 15 The 1H NMR spectrum of the solvent dissolved in deuterated methanol. Figure 2 (b) is PDMS 248.52 / 4-PBA 15 Carbon NMR spectrum of the solution in deuterated methanol;
[0028] Figure 3 PDMS in Example 1 248.52 4-PBA, thermoplastic phenolic resin NR, and the prepared intermediate PDMS 248.52 / 4-PBA 15 and PDMS 248.52 / 4-PBA 15 / NR infrared spectrum;
[0029] Figure 4 Thermogravimetric curves of the renewable phenolic resins prepared in Comparative Example 1 and Example 3;
[0030] Figure 5 The PDMS prepared in Example 3 248.52 / 4-PBA 25 Dynamic thermomechanical curves of / NR;
[0031] Figure 6 To implement the PDMS developed in Implementation 3 248.52 / 4-PBA 25 Image of solid-state reprocessing of / NR. Detailed Implementation
[0032] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.
[0033] Example 1
[0034] A method for preparing renewable phenolic resin for ablation composite materials, comprising a one-pot process and the following steps:
[0035] Step 1: Dissolve 100 parts by weight of random thermoplastic phenolic resin in tetrahydrofuran to obtain solution A.
[0036] Step 2: Dissolve 15 parts by mass of 4-formylphenylboronic acid (4-PBA) in tetrahydrofuran to obtain solution B;
[0037] Step 3: Weigh out amino-terminated polydimethylsiloxane at a molar ratio of 1:1 for amino (-NH2) to aldehyde (-CHO) groups and dissolve it in tetrahydrofuran to obtain solution C.
[0038] Step 4: Mix solutions A, B, and C, and stir at room temperature until a uniform orange transparent solution is formed, thus obtaining the resin solution. Remove approximately 80% of the solvent from the resin solution by rotary evaporation, and then vacuum cure at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 4-PBA for ablation composites. 15 / NR.
[0039] Example 2
[0040] A method for preparing renewable phenolic resin for ablation composite materials, comprising a one-pot process and the following steps:
[0041] Step 1: Dissolve 100 parts by weight of random thermoplastic phenolic resin in ethanol to obtain solution A.
[0042] Step 2: Dissolve 20 parts by mass of 4-formylphenylboronic acid (4-PBA) in ethanol to obtain solution B;
[0043] Step 3: Weigh out amino-terminated polydimethylsiloxane at a molar ratio of amino (-NH2) to aldehyde (-CHO) of 1:1 and dissolve it in ethanol to obtain solution C;
[0044] Step 4: Mix solutions A, B, and C and stir at room temperature until a uniform orange transparent solution is formed, thus obtaining the resin solution. After removing approximately 80% of the solvent by rotary evaporation, the resin solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 4-PBA for ablation composite materials. 20 / NR.
[0045] Example 3
[0046] A method for preparing renewable phenolic resin for ablation composite materials, comprising a one-pot process and the following steps:
[0047] Step 1: Dissolve 100 parts by weight of random thermoplastic phenolic resin in tetrahydrofuran to obtain solution A.
[0048] Step 2: Dissolve 25 parts by mass of 4-formylphenylboronic acid (4-PBA) in tetrahydrofuran to obtain solution B;
[0049] Step 3: Weigh out amino-terminated polydimethylsiloxane at a molar ratio of 1:1 for amino (-NH2) to aldehyde (-CHO) groups and dissolve it in tetrahydrofuran to obtain solution C.
[0050] Step 4: Mix solutions A, B, and C and stir at room temperature until a uniform orange transparent solution is formed, thus obtaining the resin solution. After removing approximately 80% of the solvent by rotary evaporation, the resin solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 4-PBA for ablation composite materials. 25 / NR.
[0051] Example 4
[0052] A method for preparing renewable phenolic resin for ablation composite materials, comprising a one-pot process and the following steps:
[0053] Step 1: Dissolve 100 parts by weight of random thermoplastic phenolic resin in tetrahydrofuran to obtain solution A.
[0054] Step 2: Dissolve 30 parts by mass of 4-formylphenylboronic acid (4-PBA) in tetrahydrofuran to obtain solution B;
[0055] Step 3: Weigh out amino-terminated polydimethylsiloxane at a molar ratio of 1:1 for amino (-NH2) to aldehyde (-CHO) groups and dissolve it in tetrahydrofuran to obtain solution C.
[0056] Step 4: Mix solutions A, B, and C and stir at room temperature until a uniform orange transparent solution is formed, which is the resin solution. After removing about 80% of the solvent by rotary evaporation, the resin solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 4-PBA for ablation composite materials. 30 / NR.
[0057] Example 5
[0058] A method for preparing renewable phenolic resin for ablation composite materials, comprising a one-pot process and the following steps:
[0059] Step 1: Dissolve 100 parts by weight of high ortho-position thermoplastic phenolic resin in tetrahydrofuran to obtain solution A.
[0060] Step 2: Dissolve 15 parts by mass of 4-formylphenylboronic acid (4-PBA) in tetrahydrofuran to obtain solution B;
[0061] Step 3: Weigh out amino-terminated polydimethylsiloxane at a molar ratio of 1:1 for amino (-NH2) to aldehyde (-CHO) groups and dissolve it in tetrahydrofuran to obtain solution C.
[0062] Step 4: Mix solutions A, B, and C, and stir at room temperature until a uniform orange transparent solution is formed, thus obtaining the resin solution. Remove approximately 80% of the solvent from the resin solution by rotary evaporation, and then vacuum cure at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 4-PBA for ablation composites. 15 / NR.
[0063] Example 6
[0064] A method for preparing renewable phenolic resin for ablation composite materials, comprising a one-pot process and the following steps:
[0065] Step 1: Dissolve 100 parts by weight of bisphenol A type thermoplastic phenolic resin in ethanol to obtain solution A;
[0066] Step 2: Dissolve 20 parts by mass of 4-formylphenylboronic acid (4-PBA) in ethanol to obtain solution B;
[0067] Step 3: Weigh out amino-terminated polydimethylsiloxane at a molar ratio of amino (-NH2) to aldehyde (-CHO) of 1:1 and dissolve it in ethanol to obtain solution C;
[0068] Step 4: Mix solutions A, B, and C and stir at room temperature until a uniform orange transparent solution is formed, thus obtaining the resin solution. After removing approximately 80% of the solvent by rotary evaporation, the resin solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 4-PBA for ablation composite materials. 20 / NR.
[0069] Example 7
[0070] A method for preparing renewable phenolic resin for ablation composite materials, comprising a one-pot process and the following steps:
[0071] Step 1: Dissolve 100 parts by weight of catechol-type thermoplastic phenolic resin in tetrahydrofuran to obtain solution A;
[0072] Step 2: Dissolve 25 parts by mass of 4-formylphenylboronic acid (4-PBA) in tetrahydrofuran to obtain solution B;
[0073] Step 3: Weigh out amino-terminated polydimethylsiloxane at a molar ratio of 1:1 for amino (-NH2) to aldehyde (-CHO) groups and dissolve it in tetrahydrofuran to obtain solution C.
[0074] Step 4: Mix solutions A, B, and C and stir at room temperature until a uniform orange transparent solution is formed, thus obtaining the resin solution. After removing approximately 80% of the solvent by rotary evaporation, the resin solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 4-PBA for ablation composite materials. 25 / NR.
[0075] Example 8
[0076] A method for preparing renewable phenolic resin for ablation composite materials, comprising a one-pot process and the following steps:
[0077] Step 1: Dissolve 100 parts by weight of bisphenol F thermoplastic phenolic resin in tetrahydrofuran to obtain solution A.
[0078] Step 2: Dissolve 30 parts by mass of 2-formylphenylboronic acid (2-PBA) in tetrahydrofuran to obtain solution B;
[0079] Step 3: Weigh out amino-terminated polydimethylsiloxane at a molar ratio of 1:1 for amino (-NH2) to aldehyde (-CHO) groups and dissolve it in tetrahydrofuran to obtain solution C.
[0080] Step 4: Mix solutions A, B, and C and stir at room temperature until a uniform orange transparent solution is formed, thus obtaining the resin solution. After removing approximately 80% of the solvent by rotary evaporation, the resin solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 2-PBA for ablation composites. 30 / NR.
[0081] Example 9
[0082] A method for preparing renewable phenolic resin for ablation composite materials, comprising a one-pot process and the following steps:
[0083] Step 1: Dissolve 100 parts by weight of naphthol-type thermoplastic phenolic resin in tetrahydrofuran to obtain solution A.
[0084] Step 2: Dissolve 30 parts by mass of 3-formylphenylboronic acid (3-PBA) in tetrahydrofuran to obtain solution B;
[0085] Step 3: Weigh out amino-terminated polydimethylsiloxane at a molar ratio of 1:1 for amino (-NH2) to aldehyde (-CHO) groups and dissolve it in tetrahydrofuran to obtain solution C.
[0086] Step 4: Mix solutions A, B, and C and stir at room temperature until a uniform orange transparent solution is formed, which is the resin solution. After removing about 80% of the solvent by rotary evaporation, the resin solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 3-PBA for ablation composite materials. 30 / NR.
[0087] Example 10
[0088] A method for preparing renewable phenolic resin for ablation composite materials, comprising a one-pot process and the following steps:
[0089] Step 1: Dissolve 100 parts by weight of cashew phenol-based thermoplastic phenolic resin in tetrahydrofuran to obtain solution A.
[0090] Step 2: Dissolve 30 parts by mass of 3,5-dicarboxyphenylboronic acid (3,5-PBA) in tetrahydrofuran to obtain solution B;
[0091] Step 3: Weigh out amino-terminated polydimethylsiloxane at a molar ratio of 1:1 for amino (-NH2) to aldehyde (-CHO) groups and dissolve it in tetrahydrofuran to obtain solution C.
[0092] Step 4: Mix solutions A, B, and C and stir at room temperature until a uniform orange transparent solution is formed, which is the resin solution. After removing about 80% of the solvent by rotary evaporation, the resin solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 3,5-PBA for ablation composites. 30 / NR.
[0093] Example 11:
[0094] This embodiment is the same as that of Embodiment 10, except that, by mass, 60 parts of 3,5-dicarboxyphenylboronic acid (3,5-PBA) are dissolved in tetrahydrofuran to form solution B.
[0095] Example 12:
[0096] This embodiment is the same as that of Embodiment 10, except that 50 parts by mass of 3,5-dicarboxyphenylboronic acid (3,5-PBA) are dissolved in tetrahydrofuran to form solution B.
[0097] Example 13
[0098] A method for preparing a renewable phenolic resin for ablation composite materials, comprising a two-step process and the following steps:
[0099] Step 1: Dissolve 15 parts by mass of 4-formylphenylboronic acid (4-PBA) in tetrahydrofuran to obtain solution A;
[0100] Step 2: Weigh out amino-terminated polydimethylsiloxane in tetrahydrofuran at a molar ratio of n(-NH2):n(-CHO) = 1:1 to obtain solution B;
[0101] Step 3: Mix solutions A and B and stir for 6 hours. After removing approximately 80% of the solvent by rotary evaporation, dry under vacuum at 60°C for 10 hours to obtain the intermediate PDMS / 4-PBA containing imine bonds. 15 ,spare;
[0102] Step 4: By mass, 100 parts of random thermoplastic phenolic resin and the imine-containing intermediate synthesized in Step 3 are dissolved together in tetrahydrofuran. The mixture is stirred at room temperature until a homogeneous solution is formed. After removing approximately 80% of the solvent by rotary evaporation, the solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 4-PBA for ablation composites. 15 / NR.
[0103] Example 14
[0104] A method for preparing a renewable phenolic resin for ablation composite materials, comprising a two-step process and the following steps:
[0105] Step 1: Dissolve 20 parts by mass of 2-formylphenylboronic acid (2-PBA) in ethanol to obtain solution A;
[0106] Step 2: Weigh out amino-terminated polydimethylsiloxane with a molar ratio of n(-NH2):n(-CHO) = 1:1 and dissolve it in ethanol to obtain solution B;
[0107] Step 3: Mix solutions A and B and stir for 4 hours. After removing approximately 80% of the solvent by rotary evaporation, dry under vacuum at 60°C for 6 hours to obtain the intermediate PDMS / 2-PBA containing imine bonds. 20 ,spare;
[0108] Step 4: By mass, 100 parts of high ortho-position thermoplastic phenolic resin and the imine-containing intermediate synthesized in Step 3 are dissolved together in ethanol. The mixture is stirred at room temperature until a homogeneous solution is formed. After removing approximately 80% of the solvent by rotary evaporation, the solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 2-PBA for ablation composites. 20 / NR.
[0109] Example 15
[0110] A method for preparing a renewable phenolic resin for ablation composite materials, comprising a two-step process and the following steps:
[0111] Step 1: Dissolve 25 parts by mass of 3-formylphenylboronic acid (3-PBA) in acetone to obtain solution A;
[0112] Step 2: Weigh out amino-terminated polydimethylsiloxane with a molar ratio of n(-NH2):n(-CHO) = 1:1 and dissolve it in acetone to obtain solution B;
[0113] Step 3: Mix solutions A and B and stir for 5 hours. After removing approximately 80% of the solvent by rotary evaporation, dry under vacuum at 60°C for 8 hours to obtain the intermediate PDMS / 3-PBA containing imine bonds. 25 ,spare;
[0114] Step 4: By mass, 100 parts of bisphenol A type thermoplastic phenolic resin and the imine-containing intermediate synthesized in Step 3 are dissolved together in acetone. The mixture is stirred at room temperature until a homogeneous solution is formed. After removing approximately 80% of the solvent by rotary evaporation, the solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 3-PBA for ablation composites. 25 / NR.
[0115] Example 16
[0116] A method for preparing a renewable phenolic resin for ablation composite materials, comprising a two-step process and the following steps:
[0117] Step 1: Dissolve 30 parts by mass of 4-formylphenylboronic acid (4-PBA) in tetrahydrofuran to obtain solution A;
[0118] Step 2: Weigh out amino-terminated polydimethylsiloxane in tetrahydrofuran at a molar ratio of n(-NH2):n(-CHO) = 1:1 to obtain solution B;
[0119] Step 3: Mix solutions A and B and stir for 4 hours. After removing approximately 80% of the solvent by rotary evaporation, dry under vacuum at 60°C for 6 hours to obtain the intermediate PDMS / 4-PBA containing imine bonds. 30 ,spare;
[0120] Step 4: By mass, 100 parts of bisphenol F type thermoplastic phenolic resin and the imine-containing intermediate synthesized in Step 3 are dissolved together in tetrahydrofuran. The mixture is stirred at room temperature until a homogeneous solution is formed. After removing approximately 80% of the solvent by rotary evaporation, the solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 4-PBA for ablation composites. 30 / NR.
[0121] Example 17
[0122] A method for preparing a renewable phenolic resin for ablation composite materials, comprising a two-step process and the following steps:
[0123] Step 1: Dissolve 30 parts by mass of 3,5-dicarboxyphenylboronic acid (3,5-PBA) in tetrahydrofuran to obtain solution A;
[0124] Step 2: Weigh out amino-terminated polydimethylsiloxane in tetrahydrofuran at a molar ratio of n(-NH2):n(-CHO) = 1:1 to obtain solution B;
[0125] Step 3: Mix solutions A and B and stir for 4 hours. After removing approximately 80% of the solvent by rotary evaporation, dry under vacuum at 60°C for 6 hours to obtain the intermediate PDMS / 3,5-PBA containing imine bonds. 30 ,spare;
[0126] Step 4: By mass, 100 parts of catechol-type thermoplastic phenolic resin and the imine-containing intermediate synthesized in Step 3 are dissolved together in tetrahydrofuran. The mixture is stirred at room temperature until a homogeneous solution is formed. After removing approximately 80% of the solvent by rotary evaporation, the solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 3,5-PBA for ablation composites. 30 / NR.
[0127] Example 18
[0128] A method for preparing a renewable phenolic resin for ablation composite materials, comprising a two-step process and the following steps:
[0129] Step 1: Dissolve 60 parts by mass of 3,5-dicarboxyphenylboronic acid (3,5-PBA) in tetrahydrofuran to obtain solution A;
[0130] Step 2: Weigh out amino-terminated polydimethylsiloxane in tetrahydrofuran at a molar ratio of n(-NH2):n(-CHO) = 1:1 to obtain solution B;
[0131] Step 3: Mix solutions A and B and stir for 4 hours. After removing approximately 80% of the solvent by rotary evaporation, dry under vacuum at 60°C for 6 hours to obtain the intermediate PDMS / 3,5-PBA containing imine bonds. 60 ,spare;
[0132] Step 4: By mass, 100 parts of naphthol-type thermoplastic phenolic resin and the imine-containing intermediate synthesized in Step 3 are dissolved together in tetrahydrofuran. The mixture is stirred at room temperature until a homogeneous solution is formed. After removing approximately 80% of the solvent by rotary evaporation, the solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 3,5-PBA for ablation composites. 60 / NR.
[0133] Example 19
[0134] A method for preparing a renewable phenolic resin for ablation composite materials, comprising a two-step process and the following steps:
[0135] Step 1: Dissolve 50 parts by mass of 3,5-dicarboxyphenylboronic acid (3,5-PBA) in tetrahydrofuran to obtain solution A;
[0136] Step 2: Weigh out amino-terminated polydimethylsiloxane in tetrahydrofuran at a molar ratio of n(-NH2):n(-CHO) = 1:1 to obtain solution B;
[0137] Step 3: Mix solutions A and B and stir for 4 hours. After removing approximately 80% of the solvent by rotary evaporation, dry under vacuum at 60°C for 6 hours to obtain the intermediate PDMS / 3,5-PBA containing imine bonds. 50 ,spare;
[0138] Step 4: By mass, 100 parts of cashew phenol-based thermoplastic phenolic resin and the imine-containing intermediate synthesized in Step 3 are dissolved together in tetrahydrofuran. The mixture is stirred at room temperature until a homogeneous solution is formed. After removing approximately 80% of the solvent by rotary evaporation, the solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PDMS / 3,5-PBA for ablation composites. 50 / NR.
[0139] Comparative Example 1:
[0140] A method for preparing a renewable phenolic resin for an ablation composite material without amino silicone oil, comprising the following steps:
[0141] Step 1: Dissolve 100 parts by weight of random thermoplastic phenolic resin in tetrahydrofuran to obtain solution A.
[0142] Step 2: Dissolve 25 parts by mass of phenylboronic acid (PBA) without aldehyde groups in tetrahydrofuran to obtain solution B.
[0143] Step 4: Mix solutions A and B and stir at room temperature until a uniform orange transparent solution is formed, which is the resin solution. After removing about 80% of the solvent by rotary evaporation, the resin solution is vacuum cured at 180°C for 10 hours to obtain the renewable phenolic resin PBNR25 for ablation composite materials.
[0144] The PDMS prepared in Example 13 248.52 / 4-PBA 15 The 1H NMR spectrum under acidic conditions is as follows: Figure 1 As shown, in a strongly acidic environment with pH=1, the characteristic proton peak of the aldehyde group (-CHO) in the spectrum is greatly enhanced, while the characteristic proton peak corresponding to the imine bond (-C=N-) is greatly weakened, indicating that the imine bond inside the system is broken and an aldehyde group is generated.
[0145] The PDMS prepared in Example 13 248.52 / 4-PBA 15 The 1H NMR spectrum was obtained by dissolving the sample in deuterated methanol solvent, and the resulting spectrum is shown below. Figure 2 As shown in (a), the characteristic chemical shift peak corresponding to the proton of the imine bond (-C=N-) appears at δ = 8.22-8.41 ppm, which proves that the prepolymer containing the imine bond has been successfully prepared. PDMS 248.52 / 4-PBA 15 The solution was dissolved in deuterated methanol and subjected to carbon NMR spectroscopy. The resulting spectrum is shown below. Figure 2 As shown in (b), the successful preparation of the imine-containing intermediate is further confirmed.
[0146] The reaction raw materials of Example 1 (PDMS with a molecular weight of 248.52 g / mol, 4-PBA, thermoplastic phenolic resin, and intermediate PDMS) 248.52 / 4-PBA 15 and PDMS 248.52 / 4-PBA 15 / NR was used for infrared spectroscopy testing, and the resulting spectrum is as follows: Figure 3 As shown, the stretching vibration peak of the phenolic hydroxyl group (Ar-OH) in the thermoplastic phenolic resin NR is significantly weakened, indicating that the phenolic hydroxyl group of the thermoplastic phenolic resin NR participates in the reaction; at the same time, PDMS 248.52 / 4-PBA 15 and PDMS 248.52 / 4-PBA 15 The infrared spectra of / NR all showed a new absorption peak at 1610 cm⁻¹, which can be attributed to the characteristic vibration peak of the imine bond (C=N), confirming the formation of the imine bond.
[0147] Thermogravimetric analysis was performed on the regenerable phenolic resins prepared in Example 3 and Comparative Example 1. The tests were conducted under a nitrogen atmosphere, with a temperature range of room temperature to 800°C and a heating rate of 10°C / min. The obtained thermogravimetric curves are shown below. Figure 4 As shown, the addition of silicone oil gives the modified phenolic resin a higher thermal decomposition temperature, PDMS 248.52 / 4-PBA 25 / NR initial decomposition temperature (T) 5％ The temperature at which weight loss occurs is 288.5℃, and the temperature at which weight loss occurs at 10% (T). 10％ The temperature was 379.4℃, which is higher than that of PBNR25, demonstrating excellent thermal stability and high temperature resistance.
[0148] The PDMS prepared in Example 3 248.52 / 4-PBA 25 / NR performs dynamic thermomechanical analysis, and the resulting dynamic thermomechanical curves are as follows: Figure 5 As shown, the glass transition temperature (Tg) of the modified resin is 141.43℃, indicating that it has good heat resistance.
[0149] The PDMS prepared in Example 3 248.52 / 4-PBA 25 / NR conducted solid-state reprocessing experiments, such as Figure 6 As shown, PDMS 248.52 / 4-PBA 25 The resin powder was pulverized and then reprocessed through compression molding: the molding temperature was 150℃~250℃, the molding pressure was 1MPa~100MPa, and the molding time was 0.5h~6h. It can be seen that the sample after multiple pulverization and hot pressing exhibits a uniform and transparent appearance, proving that the resin has reprocessability.
[0150] The thermal decomposition temperature and char residue at 800°C of the PDMS248.52 / 4-PBA / NR with different crosslinking densities prepared in Examples 1-4 and the PBNR25 cured resin prepared in Comparative Example 1 were compared. The results are shown in Table 1.
[0151] Table 1 Comparison of thermal decomposition temperature and residual carbon rate at 800℃ of recyclable phenolic resin
[0152] name T 5％ (°C) T 10％ (°C) R 800℃ (%)]] PDMS 248.52 / 4-PBA 15 / NR]]> 308.4 356.7 53.7 <![CDATA[PDMS 248.52 / 4-PBA 20 / NR]]> 314.5 396.2 57.9 <![CDATA[PDMS 248.52 / 4-PBA 25 / NR]]> 288.5 379.4 62.0 <![CDATA[PDMS 248.52 / 4-PBA 30 / NR]]> 277.6 355.2 56.0 PBNR25 176.0 298.6 61.1
[0153] Table 1 shows that by introducing a certain amount of amino silicone oil with a high temperature resistance to phenolic resin to form a dynamic covalent crosslinking network, the thermal decomposition temperature and char formation rate at high temperatures of the resulting regenerable phenolic resin are significantly improved, exhibiting good heat resistance and thermal stability. Among them, PDMS... 248.52 / 4-PBA20 / NR thermal decomposition temperature (T) 10％ ) can reach 396.2℃, PDMS 248.52 / 4-PBA 25 The char residue of / NR at 800℃ was 62%. This indicates that the construction of the dynamic cross-linking network not only endows the phenolic resin with regenerable properties, but the phenyl borate ester structure formed during the curing process also significantly improves the thermal properties of the material. Furthermore, as the ratio of PDMS to 4-PBA is adjusted, the cross-linking density changes, and the char residue exhibits a regular variation, indicating that the ablation resistance of the material can be optimized by controlling the composition.
Claims
1. A method for preparing a renewable phenolic resin for ablation composite materials, characterized in that, The preparation is carried out by a one-pot method, including the following steps: Step 1: Dissolve 100 parts by weight of thermoplastic phenolic resin in a low-boiling-point polar organic solvent to obtain solution A. Step 2: Dissolve 15-30 parts by mass of monoaldehyde aromatic boric acid compound or 30-60 parts by mass of dialdehyde arylboronic acid compound in a low-boiling-point polar organic solvent to obtain solution B. Step 3: Weigh out amino silicone oil with a molar ratio of amino (-NH2) to aldehyde (-CHO) of 1:1 and dissolve it in a low-boiling-point polar organic solvent to obtain solution C; Step 4: Mix solutions A, B, and C and stir at room temperature until a homogeneous solution is formed. After removing about 80% of the solvent by rotary evaporation, vacuum cure at 180°C for 10 hours to obtain a renewable phenolic resin for ablation composite materials.
2. A method for preparing a renewable phenolic resin for ablation composite materials, characterized in that, The preparation is carried out in two steps, including the following steps: Step 1: Dissolve 15-30 parts by mass of a monoaldehyde aromatic boric acid compound or 30-60 parts by mass of a dialdehyde arylboronic acid compound in a low-boiling-point organic solvent to obtain solution A. Step 2: Weigh out amino silicone oil with a molar ratio of n(-NH2):n(-CHO) = 1:1, dissolve it in a low-boiling-point organic solvent, and use it as solution B; Step 3: Mix solutions A and B and stir for 4-6 hours. After removing about 80% of the solvent by rotary evaporation, dry under vacuum at 60°C for 6-10 hours to obtain an intermediate containing imine bonds for later use. Step 4: By mass, 100 parts of thermoplastic phenolic resin and the imine-containing intermediate synthesized in step 3 are dissolved together in a low-boiling-point organic solvent. The mixture is stirred at room temperature until a homogeneous solution is formed. After removing about 80% of the solvent by rotary evaporation, the mixture is vacuum cured at 180°C for 10 hours to obtain a regenerable phenolic resin for ablation composite materials.
3. The method for preparing renewable phenolic resin for ablation composite materials according to any one of claims 1-2, characterized in that, The phenolic resin is one or more of the following in any proportion: high ortho-position thermoplastic phenolic resin, atactic thermoplastic phenolic resin, bisphenol A type thermoplastic phenolic resin, bisphenol F type thermoplastic phenolic resin, catechol type thermoplastic phenolic resin, naphthol type thermoplastic phenolic resin, and cashew phenol-based thermoplastic phenolic resin.
4. The method for preparing renewable phenolic resin for ablation composite materials according to claim 3, characterized in that, The monoaldehyde aromatic boric acid compound is one of 2-formylphenylboronic acid (2-PBA), 3-formylphenylboronic acid (3-PBA), or 4-formylphenylboronic acid (4-PBA); the dialdehyde aromatic boric acid compound is 3,5-diformylphenylboronic acid (3,5-PBA).
5. The method for preparing renewable phenolic resin for ablation composite materials according to claim 4, characterized in that, The amino silicone oil is an amino-terminated polydimethylsiloxane.
6. The method for preparing renewable phenolic resin for ablation composite materials according to claim 5, characterized in that, The low-boiling-point polar organic solvent is one or more of acetone, ethanol, and tetrahydrofuran mixed in any proportion.
7. A renewable phenolic resin for ablation composite materials prepared by the preparation method according to any one of claims 1-6, characterized in that, In the regenerable phenolic resin used in the ablation composite material, aldehyde-based aromatic boric acid compounds react with the hydroxyl groups of the phenolic resin and the amino groups of polydimethylsiloxane to form a polymeric cross-linked network containing dynamic covalent bonds; the thermal decomposition temperature (T) of the regenerable phenolic resin... 10％ The maximum temperature can reach 396.2℃, and the char yield can reach up to 62.0%.