A water-soluble core mold material, a method for preparing the same, and use thereof

Abstract

The present application belongs to the field of advanced material forming manufacturing, and particularly relates to a water-soluble core mold material, a preparation method and use thereof. By introducing multifunctional polar small molecules and nano fillers, a polymer adhesive component system is obtained, which is then mixed with quartz sand to prepare a polymer-based water-soluble core mold material. The thermal, mechanical and bonding properties of the composite adhesive are synergistically enhanced, and the polymer-based water-soluble core mold material prepared therefrom exhibits simultaneous enhancement of high-temperature mechanical properties, dimensional stability and water-soluble disintegration performance, and can be widely applied in the composite material manufacturing industry, especially for integrated forming manufacturing of complex hollow structure composite parts, and has good application prospects.

Description

A water-soluble core mold material, its preparation method and uses Technical Field

[0001] This invention belongs to the field of advanced composite material molding and manufacturing, specifically relating to a water-soluble mandrel material, its preparation method, and its applications. Background Technology

[0002] In the modern technology manufacturing field, with the continuous development and progress of molding, processing, and materials technologies, parts are increasingly moving towards high performance and lightweight design. Composite materials, due to their superior properties, are widely used in various manufacturing industries. Currently, a major cost in the molding and manufacturing of carbon fiber resin-based composite materials comes from mold manufacturing. For composite parts with complex geometric features such as hollow irregularities or longitudinal and transverse stiffening, traditional metal molds suffer from high manufacturing costs and difficulties in demolding, limiting the development and progress of composite material molding and manufacturing technology. Rubber airbag auxiliary mandrels have problems with poor dimensional accuracy and surface flatness, failing to meet the requirements of some high-precision manufacturing. Water-soluble mandrels can effectively solve the above problems. They have advantages such as easy molding, economic and environmental protection, high molding accuracy, and easy demolding, and are therefore widely used in the manufacturing of various high-value-added hollow variable cross-section and complex cavity structure parts.

[0003] Among water-soluble core mold types, compared to salt cores, ceramic cores, gypsum cores, and urea cores, polymer-based water-soluble core molds offer advantages such as easier molding, lower cost, environmental friendliness, and strong adjustability of water-soluble adhesive properties. They are widely used in the molding of resin-based carbon fiber composites. Furthermore, the main water-soluble polymer adhesives used include polyvinyl alcohol, polyethylene glycol, and polyvinylpyrrolidone. Due to the advantages of polymers, such as good molecular structure designability, adjustable mechanical properties and water solubility, high toughness and strength, good adhesion, significant potential for improved temperature resistance, low cost, and safety and environmental friendliness, polymer-based water-soluble core molds have excellent application prospects.

[0004] However, the currently used water-soluble polymer-based core mold materials also face some challenges and difficulties. The main problems are that the mechanical properties, high-temperature mechanical properties and stability are difficult to meet the requirements of high-temperature composite material curing and molding processes, the water solubility is not high, and the high-temperature molding application is prone to aging and cross-linking, thus losing water solubility. The current common improvement methods are mainly divided into two categories: chemical modification and blending modification. Among them, blending modification refers to using secondary valence bond forces (hydrogen bond, Coulomb force, van der Waals force, etc.) to add water-soluble polymers and other modifiers containing polar functional groups together to form a mixed system, so as to change the functional group density and aggregate structure of water-soluble polymers. Common blending modification types include: (1) blending water-soluble polymers with polymers containing polar functional groups. By constructing a hydrogen bond network system, the mechanical strength, modulus, glass transition temperature and even adhesive properties of polymer composite systems can be improved by using polymers containing polar functional groups to blend and modify water-soluble polymers. (2) Blending water-soluble polymers with polar small molecules: Adding multifunctional polar small molecules allows them to form hydrogen bonds and other supramolecular forces with the water-soluble polymer chains, constructing a hydrogen-bonded complex network system, which can improve the strength, toughness, and thermal stability of the polymer material. (3) Blending water-soluble polymers with nanofillers: These nanofillers establish connections with the polymer through secondary valence forces such as hydrogen bonds, transferring physical energy such as stress, heat, and electricity along the polymer-nanofiller network. The added nanofillers can not only improve the mechanical strength and adhesion properties of the polymer material, but also enhance its thermal stability and oxidation resistance.

[0005] Water-soluble mandrels prepared from single water-soluble polymer matrix formulations often exhibit poor mechanical properties, high-temperature mechanical properties, and stability, failing to meet the requirements of high-temperature composite material curing and molding processes, and their water solubility is low. Therefore, it is necessary to develop new modification strategies for water-soluble mandrels to further improve their mechanical properties, high-temperature mechanical properties, stability, and water solubility. Summary of the Invention

[0006] To address the problems of existing technologies, this invention provides a water-soluble mandrel material, its preparation method, and its applications.

[0007] A synergistically modified polymer adhesive is obtained by drying and curing the following raw materials in parts by weight:

[0008] Water-soluble polymer adhesive 0-100 parts

[0009] Polymers containing polar functional groups, 0-100 parts

[0010] 1-9 parts of multifunctional polar small molecules

[0011] 1-12 parts of modified nanofiller;

[0012] The polar functional group is selected from at least one of carboxyl and hydroxyl groups;

[0013] The functional groups in the multifunctional polar small molecule are selected from at least one of hydroxyl, carboxyl, and ester groups.

[0014] Preferably, the synergistically modified polymer adhesive is obtained by drying and curing the following raw materials in parts by weight:

[0015] 70 parts of water-soluble polymer adhesive

[0016] 30 parts of polymers containing polar functional groups

[0017] Three portions of multifunctional polar small molecules

[0018] Four parts of modified nanofiller.

[0019] Preferably, the water-soluble polymer adhesive is selected from polyvinyl alcohol. 、 At least one of polyethylene glycol, polyacrylic acid, polyacrylamide, and polyvinylpyrrolidone;

[0020] Preferably, the polymer containing polar functional groups is selected from at least one of carboxymethyl cellulose, chitosan, dextran, and starch;

[0021] Preferably, the multifunctional polar small molecule is selected from at least one of tannic acid, salicylic acid, citric acid, lactic acid, and malic acid;

[0022] Preferably, the modified nanofiller is selected from at least one of polydopamine-coated halloysite nanotubes, polydopamine-coated carbon nanotubes, polydopamine-coated montmorillonite, polydopamine-coated titanium dioxide, and polydopamine-coated silica.

[0023] The present invention also provides a method for preparing the above-mentioned synergistically modified polymer adhesive, comprising the following steps:

[0024] Step 1: React the water-soluble polymer adhesive solution and the polymer aqueous solution containing polar functional groups to prepare blend solution 1;

[0025] Step 2: Add the nanofiller and polydopamine to water, disperse by ultrasonication, and dry to obtain the modified nanofiller;

[0026] Step 3: After dissolving the multifunctional polar small molecules, add the modified nanofiller, stir and disperse to prepare suspension 1;

[0027] Step 4: Add suspension 1 to blend solution 1, stir and let stand to obtain synergistically modified polymer adhesive.

[0028] Preferably, in step 1, the reaction temperature is 50-70℃;

[0029] And / or, in step 2, the ultrasonic dispersion time is 10-25 min;

[0030] And / or, in step 3, the stirring and dispersion time is 1-2 hours;

[0031] And / or, in step 4, the stirring temperature is 50-60℃, the stirring time is 1-2h, and the standing time is 24-36h.

[0032] The present invention also provides the use of the above-described synergistically modified polymer adhesive in the preparation of high-temperature resistant water-soluble mandrel materials.

[0033] A water-soluble mandrel material is made by mixing the above-mentioned synergistically modified polymer adhesive and quartz sand in a weight ratio of (4-8):(300-500).

[0034] The present invention also provides a method for preparing the above-mentioned water-soluble mandrel material, comprising the following steps: mixing the synergistically modified polymer adhesive and quartz sand, and hot-pressing the mixture to prepare the water-soluble mandrel material.

[0035] Preferably, the hot pressing conditions are to maintain the temperature at 90-110°C for 0.8-1.5 hours, then raise the temperature to 120-135°C and maintain it at this temperature for 1.5-2.5 hours.

[0036] The present invention also provides the use of the above-mentioned water-soluble mandrel material in the field of advanced composite material molding and manufacturing.

[0037] This invention studies the modification of water-soluble polymer adhesive component systems from three perspectives: polymer blending modification, polar small molecule blending modification, and nanofiller blending modification. The thermal, mechanical, and adhesive properties of the composite adhesive are synergistically enhanced; the mechanical properties, high-temperature mechanical properties, dimensional stability, and water-soluble dispersion properties of the water-soluble mandrel material are improved, meeting the requirements of high-temperature composite material molding and manufacturing processes.

[0038] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0039] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Attached Figure Description

[0040] Figure 1 shows the thermogravimetric analysis (TGA) curve, the thermogravimetric rate (DTG) curve, and the initial thermal decomposition temperature (T).i and the temperature of maximum thermal weight loss rate T max a) PCMC30@TA composite system; b) PCMC30@HNT composite system; c) PCMC30@TA3@PDA-HNT4 composite system.

[0041] Figure 2 shows the mechanical property analysis (tensile strength, Young's modulus, and tensile stress-strain curves). a) PCMC30@TA composite system; b) PCMC30@HNT composite system; c) PCMC30@TA3@PDA-HNT4 composite system.

[0042] Figure 3 shows the bonding performance analysis of the adhesives by tensile shear strength. a) PCMC30@TA composite system; b) PCMC30@HNT composite system; c) PCMC30@TA3@PDA-HNT4 composite system.

[0043] Figure 4 shows the comparison of solubility (WS%) in water at pH 7. a) PCMC30@TA composite system; b) PCMC30@HNT composite system; c) PCMC30@TA3@PDA-HNT4 composite system.

[0044] Figure 5 shows the compression performance analysis of PCMC30@TA3@PDA-HNT4 water-soluble mandrel material at 160℃. a) Compressive strength; b) Compressive modulus; c) Compressive stress-strain curve.

[0045] Figure 6 shows the dimensional stability analysis of PCMC30@TA3@PDA-HNT4 water-soluble mandrel material. a) Static thermomechanical analysis curves in the temperature range of 30 to 200℃; b) Creep curves after continuous compression at 130℃ and 1.5MPa pressure for 10h.

[0046] Figure 7 shows a comparison of the water solubility and disintegration properties of PCMC30@TA3@PDA-HNT4 water-soluble core mold materials at 50℃. a) Water flow penetration rate at 50℃; b) Macroscopic morphology of the scouring surface of core molds with different formulation systems after testing; c) Schematic diagram of the mechanism by which PDA-coated HNTs promote the water solubility of adhesives as hydrophilic fillers. Detailed Implementation

[0047] In the following examples and experimental cases, reagents and raw materials not specifically described are all commercially available products.

[0048] Example 1: Preparation of PVA / CMC@TA3@PDA-HNT4 composite adhesive and film

[0049] According to the formula in Table 1, a certain amount of 10wt% PVA (brand: 2488; Maclean's reagent) aqueous solution and 4wt% carboxymethyl cellulose (CMC) (MW=90000 (DS=0.7), 50-100mPa.s; Aladdin's reagent) aqueous solution are first mixed evenly at 60℃ according to the solid content mixing ratio of (PVA2488:CMC=7:3) to obtain PVA / CMC blend adhesive solution. Halloysite nanotubes (H431905, Aladdin reagent) were coated with dopamine hydrochloride. 1 g of halloysite nanotubes (HNT) and 0.5 g of dopamine hydrochloride were added to 200 mL of deionized water and ultrasonically dispersed for 15 min. Then, 0.1 mol / L sodium hydroxide solution was added dropwise while stirring to adjust the pH to 8.5. The mixture was then stirred at room temperature for 24 h until the dispersion turned dark black. Finally, the dispersion was centrifuged, washed, dried, and ground multiple times to obtain polydopamine-coated HNT (PDA-HNT) powder. Tannic acid TA (98%, Aladdin reagent) (3 wt% of PCMC30 solid content) was dissolved in 20 mL of deionized water, and PDA-HNT powder (4 wt% of PCMC30 solid content) was added. The mixture was sealed and stirred for 2 h to obtain a TA-PDA-HNT suspension. Next, the PCMC30 blend solution was slowly added dropwise using a peristaltic pump while stirring at 50°C. After the addition was complete, stirring continued for 2 hours. Finally, the mixture was ultrasonically treated and allowed to stand for 24 hours to remove air bubbles, resulting in the PCMC30@TA3@PDA-HNT4 composite solution. The bubble-free PCMC30@TA3@PDA-HNT4 composite solution was then cast onto a glass plate and allowed to dry naturally at room temperature for 24 hours. Finally, it was dried again in a vacuum oven at 60°C for 6 hours to remove residual moisture, yielding the PCMC30@TA3@PDA-HNT4 composite film.

[0050] Example 2: Preparation of PVA / CMC@TA3@PDA-HNT4 water-soluble mandrel material

[0051] According to the formula in Table 1, the prepared PCMC30@TA3@PDA-HNT4 composite film and 160-mesh quartz sand were mixed at a solid content ratio of 6 phr:400 phr (equivalent to a mortar ratio of 1.5:10 for 10 wt% pure PVA solution and quartz sand). The mixture was then used to prepare PVA / CMC@TA3@PDA-HNT4 water-soluble core mold material under hot pressing process conditions of 100℃ / 1h→130℃ / 2h.

[0052] Table 1 Formulation composition of PVA / CMC@TA3@PDA-HNT4 water-soluble core mold composite adhesive

[0053]

[0054] The following is the method for preparing the control sample.

[0055] Comparative Example 1: Preparation of PCMC30 Adhesive and Film

[0056] The PCMC30 adhesive and film were obtained by the same method as the preparation of the PVA / CMC blend adhesive solution (PCMC30) in Example 1.

[0057] Comparative Example 2: Preparation of PVA / CMC@TA Composite Adhesive and Film

[0058] Following the formulation in Table 2, after obtaining the PCMC30 blend solution according to the method in Comparative Example 1, a certain amount of TA (mass fraction of PCMC30 solid content = 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 9wt%) was dissolved in 20ml of deionized water for later use. Then, it was slowly added dropwise to the PCMC30 composite adhesive solution using a peristaltic pump. The subsequent experimental steps were the same as in Example 1, resulting in the PCMC30@TA composite adhesive solution and film.

[0059] Comparative Example 3: Preparation of PVA / CMC@HNT Composite Adhesive and Film

[0060] According to the formulation in Table 2, a PCMC30 blend solution was prepared using the preparation method in Comparative Example 1. Then, HNT nanoclay powder (mass fraction of PCMC30 solid content = 1wt%, 2wt%, 3wt%, 4wt%, 8wt%, 12wt%) was added to 20 ml of deionized water, sealed, stirred, and dispersed for 2 h to obtain an HNT suspension. This suspension was then slowly added dropwise to the PCMC30 composite adhesive solution using a peristaltic pump. Subsequent experimental steps were the same as in Example 1, resulting in a PCMC30@HNT composite adhesive solution and a film.

[0061] Comparative Example 4: Preparation of PVA / CMC@PDA-HNT4 Composite Adhesive and Film

[0062] HNT was coated with polydopamine. 1 g of HNT and 0.5 g of dopamine hydrochloride were added to 200 mL of deionized water and ultrasonically dispersed for 15 min. Then, 0.1 mol / L sodium hydroxide solution was added dropwise while stirring to adjust the pH to 8.5. Stirring continued at room temperature for 24 h until the dispersion turned dark black. Finally, the dispersion was subjected to multiple centrifugations, washing, drying, and grinding to obtain polydopamine-coated HNT (PDA-HNT) powder. 4 wt% PDA-HNT powder was added to 20 mL of deionized water, sealed, and stirred for 2 h to obtain a PDA-HNT suspension. The remaining steps were the same as in Control Example 3, yielding a PCMC30@PDA-HNT4 composite adhesive solution and film.

[0063] Comparative Example 5: Preparation of PVA / CMC@TA3@HNT4 Composite Adhesive and Film

[0064] According to the formulation in Table 2, a PCMC30 blend solution was prepared using the preparation method in Comparative Example 1. Then, 0.309 g of TA (3 wt% of PCMC30 solid content) was dissolved in 20 ml of deionized water, and 0.417 g of HNT powder (4 wt% of PCMC30 solid content) was added. The mixture was sealed and stirred for 2 h to obtain a TA-HNT suspension. This suspension was then slowly added dropwise to the PCMC30 blend solution using a peristaltic pump. Subsequent experimental steps were the same as in Example 1, resulting in a PCMC30@TA3@HNT4 composite adhesive solution and a film.

[0065] Table 2. Composition of the control sample

[0066]

[0067]

[0068] The following experimental examples demonstrate the beneficial effects of the present invention.

[0069] Experimental Example 1: Thermal Performance Analysis of PVA / CMC@TA / HNT

[0070] The @TA3@PDA-HNT4-Mold and PCMC30-Mold used in this experimental example

[0071] @TA1-Mold, @TA2-Mold, @TA3-Mold, @HNT1-Mold, @HNT2-Mold, @HNT4-Mold, @HNT8-Mold, @HNT12-Mold, @PDA-HNT4-Mold,

[0072] The @TA3@HNT4-Mold samples were all prepared according to the methods of the examples or control examples.

[0073] I. Experimental Methods

[0074] Thermogravimetric analysis was performed on PVA and PVA composite films using a TG209F1 thermogravimetric analyzer to characterize their thermal stability. The temperature was increased from 30℃ to 800℃ at a rate of 10℃ / min under N2 atmosphere, and the thermogravimetric curves were recorded.

[0075] The glass transition temperature T of the thin film sample was determined using a Q800 dynamic thermomechanical analyzer in tensile mode. gThe test was characterized by a frequency of 1 Hz, an amplitude of 15 μm, and a heating rate of 3 °C / min. Temperature scan tests were performed in the range of 20 °C to 170 °C.

[0076] II. Experimental Results

[0077] As shown in Figure 1a, with the increase of TA content, the T of the PCMC30@TA composite system... i and T max All showed varying degrees of increase. T i The temperature increased from 276.3℃ (PCMC30) to 284.2℃ (PCMC30@TA3), an increase of 7.9℃; T max The temperature range increased from 303.6℃ (PCMC30) to 308.2℃ (PCMC30@TA3), an increase of 4.6℃. Furthermore, the dehydration weight loss rate (the mass loss rate corresponding to the first peak around 120℃ on the DTG curve) decreased to 8.63%.

[0078] Secondly, as shown in Figure 1b, with the increase of HNT content, the dehydration weight loss rate continuously decreases, and the T of PCMC30@HNT... i and T max All values ​​first increased and then decreased, with the maximum value occurring when the HNT content was 4 wt% (T). i =287.8℃, T max =321.1℃, dehydration weight loss = 7.26%). Its thermal stability is comparable to PCMC30 (T i =276.3℃, T max =303.6℃, ​​dehydration loss rate =9.60%), a significant improvement, T i and T max The temperatures increased by 11.5°C and 17.5°C, respectively.

[0079] Next, 3 wt% TA, 4 wt% HNT, and 4 wt% PDA-HNT were added to the PCMC30 system to study their synergistic effect on the thermal stability of the PCMC30 matrix. As shown in Figure 1c, compared with the PCMC30@TA and PCMC30@HNT composite systems, the T4 of PCMC30@TA3@HNT4 was significantly improved. iThe temperature was increased to 289.1℃, and the dehydration weight loss rate further decreased to 6.02%, indicating that the addition of 3wt% TA and 4wt% HNT to the PCMC30 system has a synergistic effect on enhancing its thermal stability. Furthermore, after adding 3wt% TA and 4wt% PDA-HNT to the PCMC30 system, its thermal degradation curve and initial thermal decomposition temperature were almost identical to those of the PCMC30@TA3@HNT4 complex, indicating that coating HNT with PDA (whose thermal decomposition temperature is around 180℃) does not affect its synergistic effect with TA on enhancing the thermal stability of the PCMC30 system.

[0080] Experimental results show that the addition of TA and HNT can improve the thermal stability of the PCMC30 system to a certain extent, and the addition of 3wt% TA and 4wt% PDA-HNT to the PCMC30 system has a synergistic effect on its thermal stability.

[0081] Experimental Example 2: Mechanical Property Analysis of PVA / CMC@TA / HNT

[0082] The @TA3@PDA-HNT4-Mold and PCMC30-Mold used in this experimental example

[0083] @TA1-Mold, @TA2-Mold, @TA3-Mold, @TA4-Mold, @TA5-Mold,

[0084] The samples @HNT1-Mold, @HNT2-Mold, @HNT4-Mold, @HNT8-Mold, @HNT12-Mold, @TA3, and @HNT4-Mold were all prepared according to the methods of the examples or control examples.

[0085] I. Experimental Methods

[0086] Tensile testing was conducted on the film samples using an Instron 5966 universal testing machine in tensile mode. Dumbbell-shaped standard samples (total length 115 mm, neck width 6 mm) were prepared according to GB / T1040—2006. The tensile speed was 50 mm / min, and each sample was tested 5 times, with the average value taken.

[0087] II. Experimental Results

[0088] First, we compared typical tensile properties of PCMC30@TA composite films that could be cast at 0–5 wt% TA addition levels, including tensile strength, Young's modulus, and elongation at break. As shown in Figure 2a, with the addition of TA, the tensile strength and modulus of the PCMC30@TA composite film first increased and then decreased, reaching their maximum values ​​of 137 MPa and 7.7 GPa at 3 wt% TA addition, representing increases of 26% and 13% respectively compared to PCMC30. The elongation at break also first increased and then decreased.

[0089] As shown in Figure 2b, with increasing HNT content (0-12 wt%), the mechanical strength and Young's modulus of the PCMC30@HNT composite film first increased and then decreased, reaching maximum values ​​of 145 MPa and 8.6 MPa at a HNT content of 4 wt% (representing increases of 33% and 27%, respectively). However, the elongation at break only showed a decreasing trend. These results indicate that an appropriate HNT loading has a good effect on improving the mechanical properties of the PCMC30 system.

[0090] As shown in Figure 2c, when 3 wt% TA and 4 wt% HNT are added together to the PCMC30 system, the tensile strength and elongation at break are further increased compared to the PCMC30@TA3 composite film and the PCMC30@HNT4 composite film. The tensile strength and elongation at break increase to 147 MPa and 4.15%, respectively, indicating that TA and HNT have a synergistic effect in the PCMC30 system. Compared to PCMC@TA3@HNT4, PCMC30@TA3@PDA-HNT4 shows a slight increase in tensile strength (2 MPa increase) and modulus (0.4 GPa increase).

[0091] Experimental results show that 3wt% TA and 4wt% HNT can improve the mechanical strength and modulus of the PCMC30 system. When both are added to the PCMC30 system, the tensile strength and elongation at break are further increased, indicating that TA and HNT have a synergistic effect in the PCMC30 system, and the synergistic effect of PDA-HNT and TA is stronger.

[0092] Experimental Example 3: Bonding Performance Analysis of PVA / CMC@TA / HNT

[0093] The @TA3@PDA-HNT4-Mold and PCMC30-Mold used in this experimental example

[0094] The samples @TA1-Mold, @TA2-Mold, @TA3-Mold, @TA4-Mold, @HNT0.5-Mold, @HNT1-Mold, @HNT2-Mold, @HNT4-Mold, and @TA3@HNT4-Mold were all prepared according to the methods of the examples or control examples.

[0095] I. Experimental Methods

[0096] Adhesion performance tests were conducted using an Instron 5966 universal testing machine to perform lap tensile shear tests on the adhesive samples. Following ISO 4587:2003 standards, quartz plates were used as lap joints, and the room temperature bond strength of the samples was tested at a test rate of 5 mm / min. Each group of samples was tested five times, and the average value was taken.

[0097] II. Experimental Results

[0098] As shown in Figure 3a, with the increase of TA content, the tensile shear strength of PCMC30@TA composite adhesive first increases and then decreases, reaching a maximum value of 1.47 MPa at a TA content of 3 wt% (63% higher than PCMC30), which means that PCMC30@TA3 has the best bonding strength.

[0099] As can be seen from Figure 3b, with the increase of HNT content, the tensile and shear strength of PCMC30@HNT is almost unchanged compared with that of PCMC30 matrix, both around 0.9 MPa, indicating that the addition of HNT has little effect on the bonding strength of PCMC30 system.

[0100] As shown in Figure 3c, the synergistic addition of 3 wt% TA and 4 wt% HNT to the PCMC30 adhesive system still resulted in a lower bond strength compared to the PCMC30@TA3 composite adhesive, failing to achieve the expected synergistic enhancement effect. However, after polydopamine coating modification of HNT, the bond strength of the PCMC30@TA3@PDA-HNT4 composite adhesive increased to 1.70 MPa, representing increases of 95% and 16% compared to PCMC30 and PCMC30@TA3, respectively. This indicates that TA only achieves a synergistic enhancement effect on the bond performance of the PCMC30 system when combined with PDA-HNT.

[0101] Experimental results show that the addition of TA increases the bonding strength of the PCMC30 system, while the addition of HNT has little effect on the bonding strength of the PCMC30 system. However, the synergistic addition of 3wt% TA and 4wt% PDA-HNT to the PCMC30 adhesive system has a synergistic effect on enhancing its bonding performance.

[0102] Experimental Example 4: Solubility Analysis of PVA / CMC@TA / HNT

[0103] The @TA3@PDA-HNT4-Mold and PCMC30-Mold used in this experimental example

[0104] @TA1-Mold, @TA2-Mold, @TA3-Mold, @HNT1-Mold, @HNT2-Mold, @HNT4-Mold, @HNT8-Mold, @HNT12-Mold, @PDA-HNT4-Mold,

[0105] The @TA3@HNT4-Mold samples were all prepared according to the methods of the examples or control examples.

[0106] I. Experimental Methods

[0107] The solubility of the thin film sample in a pH 7 aqueous environment was tested using the dry matter gravimetric method. The prepared thin film sample was cut into 20×20 mm pieces. 2 It is then stored in a desiccator. The dry mass before dissolution is denoted as the initial mass m. i Then, all samples were placed in beakers containing 80 mL of deionized water and soaked at room temperature for 1 hour. Subsequently, the insoluble residue was filtered and dried at 60 °C to constant weight, which is the remaining dry mass m after dissolution. f The water solubility of the sample at pH=7 is calculated by the following formula: Solubility (WS%) = m i -m f / m i ×100%. Each sample was measured 5 times, and the average value was calculated to obtain the final result.

[0108] II. Experimental Results

[0109] As shown in Figure 4a, the addition of tannic acid (TA) (not exceeding 3 wt%) reduced the solubility of the PCMC30 system to some extent, from 45.5% of PCMC30 to 37.0% of PCMC30@TA3.

[0110] However, as can be seen from Figure 4b, as the HNT content increases, the solubility WS% of the PCMC30@HNT composite system first increases and then decreases, with a maximum value of 53.0% (4wt% content).

[0111] As shown in Figure 4c, the solubility WS% of PCMC30@TA3@HNT4 is 37.6%, which is between that of PCMC30@TA3 and PCMC@HNT4. This is the result of the combined effect of TA inhibiting dissolution and HNT promoting dissolution. After HNT is modified by PDA coating and then added to the PCMC30 system together with 3wt% TA, the WS% of PCMC30@TA3@PDA-HNT4 further increases to 40.3%.

[0112] Experimental results show that the addition of TA (not exceeding 3 wt%) reduces the solubility of the PCMC30 system, while the addition of HNT promotes the solubility of PCMC30 to a certain extent. After both are added, the solubility of PCMC30@TA3@HNT4 is between that of PCMC30@TA3 and PCMC@HNT4, while the solubility of PCMC30@TA3@PDA-HNT4 is further increased, thus improving the water solubility performance.

[0113] Experimental Example 5: Mechanical Property Analysis of PVA / CMC@TA / HNT Mandrel Material

[0114] The @TA3@PDA-HNT4-Mold and PCMC30-Mold used in this experimental example

[0115] The @TA3-Mold and @PDA-HNT4-Mold water-soluble core mold materials were prepared according to the methods of the examples or comparative examples.

[0116] I. Experimental Methods

[0117] The compression performance of water-soluble mandrel blocks was tested at a certain temperature using a UTM5105S composite material high-temperature mechanical loading system (compression fixture). The compression rate was 2400±200 N / s, and the maximum sensor load was 100 kN, conforming to GB / T 17671-1999 standard. The average value was taken after five tests.

[0118] II. Experimental Results

[0119] As shown in Figure 5, compared to the PCMC30 mandrel, the addition of 3% TA increased the compressive strength by 32% and decreased the compressive modulus by 17%; the addition of 4PDA@HNT had almost no effect on the compressive strength and modulus; while adding both 3% TA and 4% PDA@HNT to PCMC30 increased the high-temperature compressive strength by 22% and slightly increased the compressive modulus by 5%. Experimental results indicate that the PVA / CMC@TA3@PDA-HNT4 mandrel material exhibits improved high-temperature compressive strength, enhanced bond strength, and improved resistance to thermal deformation.

[0120] Experimental Example 6: Dimensional Stability Analysis of PVA / CMC@TA / HNT Mandrel Material

[0121] The @TA3@PDA-HNT4-Mold and PCMC30-Mold used in this experimental example

[0122] The @TA3-Mold and @PDA-HNT4-Mold water-soluble core mold materials were prepared according to the methods of the examples or comparative examples.

[0123] I. Experimental Methods

[0124] High-temperature long-term compression creep testing was conducted on water-soluble mandrel specimens using the UTM5105S composite material high-temperature mechanical loading system (compression fixture) to characterize their high-temperature dimensional stability. The mandrel specimens were placed in a 130℃ environmental test chamber and subjected to a 1.5MPa pressure for 10 hours. The strain-time curves of the mandrel specimens were obtained, and the final creep value was calculated.

[0125] Static thermomechanical analysis (TMA) was performed using a Q400 static thermomechanical analyzer in compression mode to characterize the coefficient of thermal expansion of the core sample. The standard test sample had dimensions of 5 mm × 5 mm × 4 mm and a preload force of (4.0 ± 0.1) kPa. The sample was heated from room temperature to 200 °C at a heating rate of 5 °C / min under a N2 atmosphere.

[0126] II. Experimental Results

[0127] As shown in Figure 6a, the linear expansion coefficients of the PCMC30@TA3 and PCMC30@PDA-HNT4 core molds are 10.27 × 10⁻⁶ and 10⁻⁶, respectively. -6 / K and 10.49×10 -6 / K, compared to PCMC30 blended core mold, reduced by 2.44×10 -6 / K and 2.22×10 -6 / K; secondly, the linear expansion coefficient of the mandrel material prepared by adding 3wt% TA and 4wt% PDA-HNT to PCMC30 was further reduced to 9.67×10. -6 / K.

[0128] Furthermore, compression creep tests conducted at 130℃ on the PCMC30@TA3@PDA-HNT4 mandrel material showed that the compression creep curves of the mandrels prepared by these three formulations were similar to those of the PCMC30 blend mandrel, all exhibiting four stages: a transitional creep stage, a decreasing compressive strain stage, a creep equilibrium stage, and a constant creep rate stage. As shown in Figure 6b, the expansion amounts of the PCMC30@TA3, PCMC30@PDA-HNT4, and PCMC30@TA3@PDA-HNT4 mandrel materials in the second stage were all smaller than those of the PCMC30 blend mandrel, with the smallest being only 1.21% (PCMC30@TA3@PDA-HNT4), which is consistent with the results in Figure 6a. Considering the creep variation across all stages, the PCMC30@TA3@PDA-HNT4 mandrel material exhibited the lowest rate of compressive dimensional change.

[0129] Experimental results show that the addition of 3wt% TA and 4wt% PDA-HNT to the PCMC30 adhesive system alone can improve the dimensional stability of the mandrel material under thermal expansion and its resistance to thermal deformation. When the two are added together, they produce a synergistic effect in the PCMC30 system, which improves the mandrel's resistance to thermal deformation and enhances the dimensional stability of the mandrel material.

[0130] Experimental Example 7: Water Solubility and Collapse Analysis of PVA / CMC@TA / HNT Mandrel Material

[0131] The @TA3@PDA-HNT4-Mold and PCMC30-Mold used in this experimental example

[0132] The @TA3-Mold and @PDA-HNT4-Mold water-soluble core mold materials were prepared according to the methods of the examples or comparative examples.

[0133] I. Experimental Methods

[0134] The water flow erosion test device and method of patent CN116223311A were used to test the water solubility and disintegration performance of the core mold sample.

[0135] II. Experimental Results

[0136] As shown in Figure 7a, compared to the PCMC30 blended mandrel, the water flow penetration rate of the PCMC30@TA3 mandrel material decreased to 0.31 mm / s, a reduction of 74%; while the water flow penetration rate of the PCMC30@PDA-HNT4 mandrel material increased to 1.36 mm / s, an improvement of 14%; and

[0137] The water flow penetration rate of the PCMC30@TA3@PDA-HNT4 core mold material still decreased to 0.42 mm / s, a reduction of 65%. Furthermore, looking at the scouring surface collapse area of ​​the core molds prepared by the four formulations in Figure 7b, the PCMC30@PDA-HNT4 core mold material had the largest, followed by the PCMC30 blend core mold material, while the water-soluble collapse areas of the PCMC30@TA3 and PCMC30@PDA-HNT4 core mold materials were relatively small. As shown in Figure 7c, the polydopamine PDA coating, due to its high dispersibility and high hydrophilicity in aqueous solution, further enhances the hydrophilicity of PDA@HNT, thereby increasing the water-soluble collapse rate.

[0138] Experimental results show that the addition of TA significantly reduces the water solubility and disintegration properties of the PCMC30 mandrel material. Conversely, the addition of PDA-HNT can improve its water solubility and disintegration properties.

[0139] The water-soluble and collapsible properties of the PCMC30@TA3@PDA-HNT4 core mold material are the result of the combined effect of the inhibitory effect of TA and the promoting effect of PDA-HNT. However, in terms of the degree of reduction in water flow penetration rate, the inhibitory effect of TA is more obvious.

[0140] In summary, this invention explores the modification of water-soluble PVA adhesive components from three perspectives: polymer blending modification, polar small molecule blending modification, and nanofiller blending modification. Carboxymethyl cellulose (CMC), tannic acid (TA), and polydopamine-coated travertine nanotubes (PDA-HNT) were selected. The results show that the thermal, mechanical, and adhesive properties of the PCMC30@TA3@PDA-HNT4 composite adhesive are enhanced, and its water solubility is improved. The PCMC30@TA3@PDA-HNT4 water-soluble mandrel material exhibits superior overall mechanical, high-temperature mechanical, and water-soluble properties, with improved compressive strength, enhanced dimensional stability, and a minimal reduction in water-soluble dispersion rate. This invention can address the problem that water-soluble mandrels prepared from a single PVA matrix formulation often fail to meet the requirements of high-temperature composite material curing processes in terms of mechanical, high-temperature mechanical, and stability performance.

Claims

1. A synergistically modified polymer adhesive, characterized in that, It is obtained by drying and curing the following raw materials in parts by weight: 70-100 parts of water-soluble polymer adhesive, 30-100 parts of polymer containing polar functional groups, 1-9 parts of multifunctional polar small molecules, and 1-12 parts of modified nanofiller; wherein the water-soluble polymer adhesive is polyvinyl alcohol; the polymer containing polar functional groups is carboxymethyl cellulose; the multifunctional polar small molecule is tannic acid; and the modified nanofiller is polydopamine-coated halloysite nanotubes; the polymer adhesive... The preparation method of the agent includes the following steps: Step 1, reacting a water-soluble polymer adhesive solution and a polymer aqueous solution containing polar functional groups to prepare a blend solution 1; Step 2, adding nanofiller and polydopamine to water, ultrasonically dispersing, and drying to obtain modified nanofiller; Step 3, dissolving multifunctional polar small molecules, adding modified nanofiller, stirring and dispersing to prepare suspension 1; Step 4, adding suspension 1 to blend solution 1, stirring and allowing to stand to obtain synergistically modified polymer adhesive.

2. The synergistically modified polymer adhesive according to claim 1, characterized in that, It is obtained by drying and curing the following raw materials in parts by weight: 70 parts water-soluble polymer adhesive, 30 parts polymer containing polar functional groups, 3 parts multifunctional polar small molecules, and 4 parts modified nanofillers.

3. The method for preparing the synergistically modified polymer adhesive according to claim 1 or 2, characterized in that, The process includes the following steps: Step 1, reacting a water-soluble polymer adhesive solution with an aqueous polymer solution containing polar functional groups to prepare a blend solution 1; Step 2, adding nanofillers and polydopamine to water, ultrasonically dispersing, and drying to obtain modified nanofillers; Step 3, dissolving multifunctional polar small molecules, adding the modified nanofillers, stirring and dispersing to prepare a suspension 1; Step 4, adding suspension 1 to blend solution 1, stirring, and allowing to stand to obtain a synergistically modified polymer adhesive.

4. Use of the synergistically modified polymer adhesive of claim 1 or 2 in the preparation of high-temperature resistant water-soluble core mold materials.

5. A water-soluble core mold material, characterized in that, It is made by mixing the synergistically modified polymer adhesive as described in claim 1 or 2 with quartz sand in a weight ratio of (4~8):(300~500).

6. The method for preparing the water-soluble core mold material according to claim 5, characterized in that, The process includes the following steps: mixing the synergistically modified polymer adhesive with quartz sand, hot-pressing the mixture, and then preparing a water-soluble mandrel material.

7. The use of the water-soluble mandrel material of claim 5 in the field of advanced composite material molding and manufacturing.

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