Shape memory phenolic foam and preparation method thereof

Abstract

The present invention provides a shape memory phenolic foam and a preparation method thereof, belonging to the field of shape memory polymer synthesis technology. The shape memory phenolic foam comprises by weight: 100 parts of resol phenolic resin, 10-30 parts of toughening agent, 1-15 parts of curing agent, 5-10 parts of foaming agent, 5-10 parts of surfactant; the toughening agent comprises diisocyanate. The present invention improves the flexibility of the phenolic structure by introducing a longer flexible chain on the benzene ring structure of the resol phenolic, increases the distance between the internal cross-linking points of the shape memory phenolic foam, and makes the molecular structure of the shape memory phenolic foam have two molecular chain segment structures of hard segment and soft segment, and the soft segment cooperates with the hard segment (benzene ring) so that the phenolic foam has shape memory performance, and the deformation ability is improved, the shape recovery rate is fast, the shape fixation rate and the shape recovery rate are high.

Description

Technical Field

[0001] The invention relates to the technical field of shape memory polymer synthesis, in particular to a shape memory phenolic foam and a preparation method thereof. Background Art

[0002] Shape memory polymers (SMPs) are a branch of smart materials that provide a new solution to complex engineering problems. Due to the various driving modes, low cost, easy processing and biocompatibility of shape memory polymers, they are widely used in multiple disciplines and fields, such as deformable aircraft, smart fabrics, smart medical devices, minimally invasive surgical implants, heat shrink tubing for packaging electronic components, etc.

[0003] Shape memory polymer foam is a porous polymer obtained by foaming a shape memory polymer as a matrix material. It has the characteristics of low density, light weight and shape memory effect. It is a newly developed shape memory polymer material with great application prospects in the fields of biomedicine and aerospace. The performance of shape memory polymer foam is crucial to the selection of shape memory polymer matrix.

[0004] Phenolic foam is a polymer material that combines the advantages of low price, excellent mechanical properties, good heat resistance, good flame retardancy, and low smoke rate. It plays a very important role in the fields of high temperature resistant adhesives. Phenolic foam has many properties that make it attractive for many engineering applications, such as insulation, weight reduction, energy absorption, and fire prevention. Compared with other foam materials, phenolic foam has excellent flame retardant properties, but because its molecular chain contains more rigid benzene ring structures, the mechanical properties of phenolic resin are poor, such as high brittleness, poor toughness, and low impact resistance. In addition, ordinary phenolic foam does not have shape memory properties, which limits the further development of phenolic resin. Summary of the invention

[0005] In view of the above problems in the prior art, the present invention provides a shape memory phenolic foam and a preparation method thereof.

[0006] To achieve the above object, the present invention is specifically implemented through the following technical solutions:

[0007] The present invention provides a shape memory phenolic foam, the general structural formula of which is shown in formula (1):

[0008]

[0009] Wherein, the structural formula of R is shown in formula (2);

[0010]

[0011] In formula (1)-(2), R1 is selected from one or more of the groups shown in formula (3)-(7);

[0012]

[0013]

[0014] Furthermore, the shape memory phenolic foam comprises, by weight: 100 parts of resol phenolic resin, 10-30 parts of toughening agent, 1-15 parts of curing agent, 5-10 parts of foaming agent, and 5-10 parts of surfactant; wherein the toughening agent comprises diisocyanate.

[0015] Furthermore, the shape memory phenolic foam comprises, by weight: 100 parts of resol phenolic resin, 20-25 parts of toughening agent, 1-15 parts of curing agent, 5-10 parts of foaming agent, and 5-10 parts of surfactant.

[0016] Furthermore, the toughening agent also includes polyethylene glycol, and the weight ratio of the polyethylene glycol to the diisocyanate is 0-1:1.

[0017] Furthermore, the molecular weight of the polyethylene glycol is 200-800.

[0018] Furthermore, the diisocyanate is one or more of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate.

[0019] Furthermore, the curing agent includes one or more of anhydride curing agents, amine curing agents, inorganic acid curing agents or synthetic resin oligomer curing agents.

[0020] Furthermore, the foaming agent includes one or more of n-butane, n-pentane, isopentane, cyclopentane, n-hexane and n-heptane.

[0021] Furthermore, the surfactant includes one or more of polysorbate 80, polysorbate 85, Span 85, fatty acid glyceride, stearic acid, and sodium dodecylbenzene sulfonate.

[0022] In addition, the present invention provides a method for preparing the shape memory phenolic foam as described above, comprising the following steps:

[0023] S1, adding diisocyanate to the resol phenolic resin, and mixing well to obtain solution 1;

[0024] S2, adding a curing agent and a foaming agent to the solution one in sequence, mixing them evenly, to obtain a solution two;

[0025] S3, removing impurities in the second solution, then adding a surfactant, mixing evenly, to obtain a third solution;

[0026] S4, pouring the solution three into the preheated mold, heating and curing, and then demolding to obtain the shape memory phenolic foam.

[0027] Furthermore, in step S4, the mold is preheated to 75-90°C; the curing temperature of the heating curing is 80-110°C, and the curing time is 10-12h.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] The invention introduces a longer flexible chain (R1 group) into the benzene ring structure of resol phenolic, thereby improving the flexibility of the phenolic structure, increasing the distance between the internal cross-linking points of the shape memory phenolic foam, and making the molecular structure of the shape memory phenolic foam have two molecular chain segment structures, namely, a hard segment and a soft segment. The hard segment (benzene ring) serves as the fixed phase of the phenolic foam and plays a decisive role when the foam freezes its shape. The introduced soft segment serves as the reversible phase of the phenolic foam and plays a decisive role when the resin is heated to a temperature above the glass transition temperature for deformation. That is, the soft segment in the molecular structure cooperates with the hard segment (benzene ring) so that the phenolic foam has shape memory performance and the deformation ability is improved. Specifically, the shape memory phenolic foam has a fast shape recovery rate and a high shape fixation rate and shape recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 This is a physical picture of the shape memory phenolic foam according to an embodiment of the present invention;

[0032] Figure 2 This is an infrared spectrum of the shape memory phenolic foam prepared in Example 1 of the present invention;

[0033] Figure 3 This is a scanning electron microscope image of the shape memory phenolic foam prepared in Example 2 of the present invention, wherein a is SMPF1, b is SMPF2, c is SMPF3, and d is SMPF4;

[0034] Figure 4 This is a scanning electron microscope image of the shape memory phenolic foam prepared in Example 3 of the present invention, wherein e is SMPF5, f is SMPF6, g is SMPF7, and h is SMPF8;

[0035] Figure 5 This is a test diagram of the deformation recovery ability of the shape memory phenolic foam prepared in Example 1 of the present invention;

[0036] Figure 6 This is a differential scanning calorimetry test diagram of the shape memory phenolic foam prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0037] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. In addition, the meanings of the terms "comprising", "containing", and "having" are non-restrictive, and other steps and other components that do not affect the results can be added. Unless otherwise specified, materials, equipment, and reagents are all commercially available.

[0038] In order to better understand the present invention but not to limit the scope of the present invention, all the numbers used in the present invention to express the amount, percentage, and other numerical values ​​should be understood as modified by the word "about" in all cases. Therefore, unless otherwise specified, the numerical parameters listed in the specification and claims are approximate values, which may be changed according to the different ideal properties to be obtained. Each numerical parameter should at least be regarded as obtained according to the reported significant figures and by conventional rounding methods.

[0039] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0040] The embodiment of the present invention provides a shape memory phenolic foam, the general structural formula of which is shown in formula (1):

[0041]

[0042] Wherein, the structural formula of R is shown in formula (2);

[0043]

[0044] In formula (1)-(2), R1 is selected from one or more of the groups shown in formula (3)-(7);

[0045]

[0046]

[0047] The shape memory phenolic foam provided by the present invention improves the flexibility of the phenolic structure by introducing a longer flexible chain (R1 group) into the benzene ring structure of resol phenolic, increases the distance between the cross-linking points inside the shape memory phenolic foam, and makes the molecular structure of the shape memory phenolic foam have two molecular chain segment structures, namely, hard segment and soft segment. The hard segment (benzene ring) serves as the fixed phase of the phenolic foam and plays a decisive role when the foam freezes its shape. The introduced soft segment serves as the reversible phase of the phenolic foam and plays a decisive role when the resin is heated to above the glass transition temperature for deformation. That is, the soft segment in the molecular structure cooperates with the hard segment (benzene ring) so that the phenolic foam has shape memory performance and the deformation ability is improved. Specifically, the shape memory phenolic foam has a fast shape recovery rate and a high shape fixation rate and shape recovery rate.

[0048] Specifically, the raw materials of the shape memory phenolic foam include, by weight, 100 parts of resol phenolic resin, 10-30 parts of toughening agent, 1-15 parts of curing agent, 5-10 parts of foaming agent, and 5-10 parts of surfactant; the toughening agent includes diisocyanate.

[0049] The present invention utilizes a toughening agent with a linear structure to modify phenolic formaldehyde, and the alcohol hydroxyl group (-OH) on the resol phenolic formaldehyde molecule reacts with the isocyanate group (-N=C=O) in the long chain of the toughening agent molecule, that is, one molecule of -OH reacts with one molecule of -N=C=O to generate one molecule of -NH-COO-, thereby introducing a long chain with flexibility into the benzene ring of the phenolic formaldehyde structure, so that when the phenolic formaldehyde is cured, the distance between the crosslinking points in the phenolic formaldehyde is greatly increased, and the crosslinking density thereof is reduced, so that the phenolic formaldehyde foam has both soft segment and hard segment structures, improves the shape memory performance, and is conducive to significantly improving the mechanical properties of the phenolic formaldehyde foam, such as the toughness, so that the shape memory phenolic formaldehyde foam provided by the present invention can be applied in more fields.

[0050] Generally, compounds containing two isocyanate groups can react with resol molecules to form shape memory phenolic resins. Therefore, the present invention does not specifically limit the types of diisocyanates. In a specific embodiment, preferably, the diisocyanate is one or more of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), and hexamethylene diisocyanate (HDI). The aforementioned diisocyanates have suitable reactivity, do not need to add catalysts, and the reaction conditions are mild and controllable.

[0051] It is understandable that the types of materials and material ratios participating in the reaction will have a certain impact on the physical and chemical properties of the prepared shape memory phenolic foam. The higher the proportion of the toughening agent participating in the reaction, the higher the proportion of the flexible long chain in the prepared shape memory phenolic foam, the higher the toughness of the shape memory phenolic foam, the lower the glass transition temperature, that is, the lower the deformation temperature, but as the proportion of the toughening agent increases, gel is easily formed during the curing process, which leads to foaming failure. When the dosage ratio of the toughening agent to the resol phenolic resin is lower than 15:100, foaming failure will also be easily caused due to bubble collapse. Preferably, the raw materials of the shape memory phenolic foam include 100 parts of resol phenolic resin, 20-25 parts of toughening agent, 1-15 parts of curing agent, 5-10 parts of foaming agent, and 5-10 parts of surfactant by weight. Under this material ratio, a shape memory phenolic foam with a low deformation temperature can be obtained, and the pores are evenly distributed, the foam has good toughness, and it is not easy to fall off and powder. The shape memory phenolic foam with a low deformation temperature can be applied in aerospace and other fields.

[0052] Preferably, the toughening agent further comprises polyethylene glycol, and the weight ratio of the polyethylene glycol to the diisocyanate is 0-1:1.

[0053] As mentioned above, the alcoholic hydroxyl group on polyethylene glycol can also react with the -N=C=O group on diisocyanate. Polyethylene glycol contains two alcoholic hydroxyl groups, and diisocyanate contains two -N=C=O groups. When an alcoholic hydroxyl group on polyethylene glycol is connected to an isocyanate group on diisocyanate, the molecular chain will become longer, which plays a role of chain extension, making the molecular structure more flexible, and the molecular chain has good fluidity, which is conducive to reducing the glass transition temperature of the shape memory phenolic foam. Therefore, the toughening agent can also include polyethylene glycol that plays a chain extension role, and the amount of polyethylene glycol is limited to less than 50% of the total amount of the toughening agent. This is because diisocyanate has two isocyanate functional groups and polyethylene glycol has two hydroxyl functional groups. If the amount of polyethylene glycol is too high, diisocyanate will react more with polyethylene glycol, and both cannot be grafted to the hydroxyl group of the benzene ring of the resol phenolic molecule, thereby affecting the shape memory performance. Preferably, the weight ratio of the polyethylene glycol to the diisocyanate is 0.2-0.7:1.

[0054] The molecular weight of the polyethylene glycol is 200-800, for example, it can be one or more of PEG200 (molecular weight of 200g / moL), PEG400 (molecular weight of 400g / moL), PEG600 (molecular weight of 600g / moL), and PEG800 (molecular weight of 800g / moL).

[0055] Optionally, the resol resin is a product obtained by an addition reaction of a phenolic compound and an aldehyde compound under the action of an alkaline catalyst. The phenolic compound includes, but is not limited to, one or more of phenol, cresol, fluorophenol, nonylphenol, octylphenol, xylenol, cardanol, aralkylphenol or bisphenol A; the aldehyde compound includes, but is not limited to, one or more of formaldehyde, paraformaldehyde, furfural or acetaldehyde.

[0056] Optionally, the curing agent includes one or more of anhydride curing agents, amine curing agents, inorganic acid curing agents or synthetic resin oligomer curing agents.

[0057] Optionally, the foaming agent includes one or more of n-butane, n-pentane, isopentane, cyclopentane, n-hexane, and n-heptane. The shape memory phenolic foam of the present invention is foamed by a physical foaming method, which refers to a method in which only physical structural changes occur during the foaming process of the shape memory phenolic resin without chemical reactions to achieve a foaming effect.

[0058] Optionally, the surfactant includes one or more of polysorbate 80, polysorbate 85, Span 85, fatty acid glycerides, stearic acid, and sodium dodecylbenzene sulfonate.

[0059] Another embodiment of the present invention provides a method for preparing the shape memory phenolic foam as described above, comprising the following steps:

[0060] S1, adding diisocyanate to the resol phenolic resin, and mixing well to obtain solution 1;

[0061] S2, adding a curing agent and a foaming agent to the solution one in sequence, mixing them evenly, to obtain a solution two;

[0062] S3, removing impurities in the second solution, then adding a surfactant, mixing evenly, to obtain a third solution;

[0063] S4, pouring the solution three into the preheated mold, heating and curing, and then demolding to obtain the shape memory phenolic foam.

[0064] The preparation method of the shape memory phenolic foam has the same advantages as the shape memory phenolic foam described above over the prior art, which will not be described in detail. In addition, the preparation method of the shape memory phenolic foam provided by the present invention has a simple process and readily available raw materials.

[0065] Figure 1A typical physical picture of the shape memory phenolic foam prepared by the present invention is shown in the figure. It can be clearly seen that the shape memory phenolic foam has a porous structure. After compression, it can maintain its temporary shape after compression and will only restore its shape after receiving a response signal. This characteristic enables the shape memory foam to have application prospects that ordinary foams do not have.

[0066] In step S1, the preparation method of the resol phenolic resin includes: placing the resol phenolic solution in a vacuum drying oven at 60° C. for 40 minutes to remove water and a small amount of impurities such as ethanol in the resol phenolic solution to obtain the resol phenolic resin.

[0067] In step S4, the mold is preheated to 75-90°C; the curing temperature of the heating curing is 80-110°C, and the curing time is 10-12h.

[0068] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually based on the conditions recommended by the manufacturer.

[0069] Example 1

[0070] A shape memory phenolic foam comprises 100 parts of resol phenolic resin, 15-30 parts of hexamethylene diisocyanate toughening agent, 10 parts of phosphoric acid curing agent, 5 parts of isopentane foaming agent, and 8 parts of polysorbate-80 surfactant. Under the above material ratio, the mass fraction of the toughening agent is adjusted to 15 parts, 20 parts, 25 parts, and 30 parts respectively, and the prepared shape memory phenolic foams are named SMPF-a, SMPF-b, SMPF-c, and SMPF-d respectively.

[0071] The preparation method of the shape memory phenolic foam comprises the following steps:

[0072] S1, adding diisocyanate to the resol phenolic resin, and mixing well to obtain solution 1;

[0073] The preparation method of the resol phenolic resin comprises: placing the resol phenolic solution in a vacuum drying oven at 60° C. for 40 minutes, removing water and a small amount of impurities such as ethanol in the resol phenolic solution, and obtaining the resol phenolic resin.

[0074] S2, adding a curing agent to solution 1, stirring for 60 seconds, then adding a foaming agent, stirring for 30 seconds to mix the solution evenly, to obtain solution 2;

[0075] S3, removing impurities in solution 2, then adding a surfactant, stirring for 60 seconds to mix the solution evenly, and obtaining solution 3;

[0076] S4. Pour solution 3 into a mold preheated to 80°C, heat to 100°C for curing for 3h, then heat to 120°C for curing for 6h, then cool to room temperature, and demold to obtain shape memory phenolic foam.

[0077] Figure 2 The infrared spectra of shape memory phenolic foams prepared with different mass fractions of toughening agents and other conditions such as the same curing temperature, where PF is the infrared spectrum curve of phenolic foam (without shape memory modification and without toughening agent added), the toughening agent ratios of SMPF-a to SMPF-d increase in sequence, and the mass ratios of toughening agent to resol phenolic resin are 15:100, 20:100, 25:100, and 30:100, respectively. -1 The peak at 2915cm is the infrared absorption peak of phenolic hydroxyl group (Ar-OH); -1 The peak at 1403cm is the absorption peak of aldehyde CH. -1 The weak absorption peak at 2275-2250cm belongs to the bending vibration of isocyanate, but there is no weak absorption peak in the infrared spectrum of pure phenolic foam PF. -1 There is no absorption characteristic peak of N=C=O at 1662cm -1 The characteristic peaks of carbonyl (C=O) in the carbamate at all appeared in the infrared spectra of SMPF-a, SMPF-b, SMPF-c and SMPF-d. The above results show that the diisocyanate reacts completely with the -CH2OH of the phenolic resin, and the linear chain segments of the diisocyanate are successfully introduced into the molecular structure of the phenolic resin.

[0078] The glass transition temperature of the shape memory phenolic foam of this embodiment is about 130°C after the Differential Scanning Calorimetry (DSC) test. In order to test the deformation recovery ability of the shape memory phenolic foam, the shape memory phenolic foam is molded at its glass transition temperature, the shape memory phenolic foam of the initial shape is compressed to 50% of its own height, and then the molded shape memory phenolic foam is placed on a 140°C heating table to observe the change of its recovery state over time. Figure 5It can be seen that in the initial state (0s), the height of the shape memory phenolic foam is relatively low. After 20s, the height of the foam begins to increase. As time goes by, the height of the foam gradually increases. After 50s, the shape memory phenolic foam has basically returned to the initial state. After 60s, the shape memory phenolic foam completely returns to the initial height, that is, the shape memory phenolic foam returns to the initial state from the compressed state, which only takes 60s. This shows that compared with conventional phenolic foam, the shape memory phenolic foam provided by the embodiment of the present invention has a shape memory function, and has the advantages of fast shape recovery rate, high shape fixation rate and shape recovery rate. In addition, the shape memory phenolic foam is not easy to crack or damage when compressed, and has great value in the engineering application of phenolic materials.

[0079] Example 2

[0080] A shape memory phenolic foam comprises 100 parts of resol phenolic resin, 30 parts of diphenylmethane diisocyanate as a toughening agent, 10 parts of p-toluenesulfonic acid curing agent, 6 parts of n-hexane foaming agent, and 10 parts of polysorbate-80 surfactant. The preparation method is basically the same as that of Example 1, except that solution three is poured into molds preheated to 75° C., 80° C., 85° C., and 90° C., respectively, for subsequent curing reactions. The prepared shape memory phenolic foams are named SMPF1, SMPF2, SMPF3, and SMPF4, respectively.

[0081] Figure 3 The scanning electron microscope image of the shape memory phenolic foam prepared in this embodiment is shown, where from left to right, a is SMPF1, b is SMPF2, c is SMPF3, and d is SMPF4. It can be seen from the figure that the pore diameter of SMPF1 is 140-190μm, the pore diameter of SMPF2 is 170-260μm, the pore diameter of SMPF3 is 240-310μm, and the pore diameter of SMPF4 is 290-420μm. This embodiment controls the pore diameter by controlling the foaming temperature of the foam. The method is simple and effective, with strong controllability, and the prepared shape memory phenolic foam has shape memory performance and a high shape fixation rate and recovery rate.

[0082] Example 3

[0083] A shape memory phenolic foam comprises 100 parts of resol phenolic resin, 30 parts of diphenylmethane diisocyanate toughening agent, 10 parts of p-toluenesulfonic acid curing agent, 5-10 parts of n-hexane foaming agent, and 10 parts of polysorbate-85 surfactant. Under the aforementioned material ratio, the mass fractions of the foaming agent are adjusted to 5 parts, 7 parts, 9 parts, and 10 parts, respectively. The preparation method is the same as that of Example 1, and the prepared shape memory phenolic foams are named SMPF5, SMPF6, SMPF7, and SMPF8, respectively.

[0084] Figure 4 The scanning electron microscope image of the shape memory phenolic foam prepared in this embodiment is shown, where from left to right, e is SMPF5, f is SMPF6, g is SMPF7, and h is SMPF8. It can be seen from the figure that the pore diameter of SMPF5 is 160-250μm, the pore diameter of SMPF6 is 220-320μm, the pore diameter of SMPF7 is 300-400μm, and the pore diameter of SMPF8 is 320-450μm. This embodiment controls the pore diameter by controlling the amount of foaming agent. The method is simple and effective, with strong controllability, and the prepared shape memory phenolic foam has shape memory performance and a high shape fixation rate and recovery rate.

[0085] Example 4

[0086] A shape memory phenolic foam comprises 100 parts of resol phenolic resin, 15-30 parts of toughening agent, 10 parts of hydrochloric acid as curing agent, 6 parts of n-hexane foaming agent, and 10 parts of polysorbate 80 as surfactant. Under the above-mentioned material ratio, the mass fractions of the toughening agent are adjusted to 15 parts (100% diphenylmethane diisocyanate), 15 parts (70% diphenylmethane diisocyanate and 30% polyethylene glycol), 30 parts (70% diphenylmethane diisocyanate and 30% polyethylene glycol), and 30 parts (50% diphenylmethane diisocyanate and 50% polyethylene glycol), respectively. The preparation method is the same as that of Example 1, and the prepared shape memory phenolic foams are named SMPF9, SMPF10, SMPF11, and SMPF12 in sequence.

[0087] Tested by Differential Scanning Calorimetry (DSC), see Figure 6, the horizontal axis temperature corresponding to the position marked by the arrow is the glass transition temperature of this foam. It can be seen that the glass transition temperature of SMPF9 is about 135°C, the glass transition temperature of SMPF10 is about 122°C, the glass transition temperature of SMPF11 is about 110°C, and the glass transition temperature of SMPF12 is about 101°C. It can be seen that the toughening agent has a certain influence on the glass transition temperature of the shape memory phenolic foam, and the more the toughening agent is used, the lower the glass transition temperature of the shape memory phenolic foam, and the higher the content of polyethylene glycol in the toughening agent component, the lower the glass transition temperature of the shape memory phenolic foam. This is because with the introduction of polyethylene glycol, the flexible segments in the resol phenolic molecule become more, the molecular chain becomes longer, and the flexibility of the molecule increases, resulting in a decrease in its crosslinking density and a decrease in its glass transition temperature. In this embodiment, the glass transition temperature of the shape memory phenolic foam is controlled by changing the amount of toughening agent and the ratio of the toughening agent components. The method is simple, effective and highly controllable. The prepared shape memory phenolic foam has shape memory properties and a high shape fixation rate and recovery rate.

[0088] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for preparing shape memory phenolic foam, characterized in that: The steps include: S1. Add 10-30 parts of diisocyanate, a toughening agent, to 100 parts of resol phenolic resin by weight, and mix well to obtain solution 1; S2, adding 1-15 parts of curing agent and 5-10 parts of foaming agent to the solution 1 in sequence, mixing evenly, to obtain solution 2; S3, removing impurities from the second solution, then adding 5-10 parts of a surfactant, mixing evenly, to obtain a third solution; S4, pouring the solution three into the preheated mold, heating and curing, and then demolding to obtain the shape memory phenolic foam.

2. The method for preparing the shape memory phenolic foam according to claim 1, characterized in that: The shape memory phenolic foam comprises, by weight: 100 parts of resol phenolic resin, 20-25 parts of toughening agent, 1-15 parts of curing agent, 5-10 parts of foaming agent, and 5-10 parts of surfactant.

3. The method for preparing the shape memory phenolic foam according to claim 1, characterized in that: The diisocyanate is one or more of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate.

4. The method for preparing the shape memory phenolic foam according to claim 1, characterized in that: The curing agent includes one or more of anhydride curing agents, amine curing agents, inorganic acid curing agents, and synthetic resin oligomer curing agents.

5. The method for preparing the shape memory phenolic foam according to claim 1, characterized in that: The foaming agent includes one or more of n-butane, n-pentane, isopentane, cyclopentane, n-hexane and n-heptane; The surfactant includes one or more of polysorbate 80, polysorbate 85, Span 85, fatty acid glyceride, stearic acid, and sodium dodecylbenzene sulfonate.

6. The method for preparing the shape memory phenolic foam according to claim 1, characterized in that: In step S4, the mold is preheated to 75-90° C.; The curing temperature of the heating curing is 80-110° C., and the curing time is 10-12 hours.

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