CN115491030B

CN115491030B - Alkynyl modified polyamide/lignin shape memory composite material and preparation method thereof

Info

Publication number: CN115491030B
Application number: CN202211315074.5A
Authority: CN
Inventors: 李明; 杨晨; 朱晨杰; 庄伟�; 谭卓涛; 沈涛; 杨朋朋; 应汉杰
Original assignee: Nanjing Tech University
Current assignee: Nanjing Tech University
Priority date: 2022-10-26
Filing date: 2022-10-26
Publication date: 2023-08-08
Anticipated expiration: 2042-10-26
Also published as: CN115491030A

Abstract

The invention discloses a kind ofThe alkynyl modified polyamide/lignin shape memory composite material is prepared from the following components in parts by weight: 10-50 parts of alkynyl modified lignin and 50-90 parts of modified polyamide shown in a formula I. The composite material provided by the invention forms a co-network structure, has lignin-polyamide cross-linked network phase and polyamide glass transition temperature, and has better high-temperature shape memory performance.

Description

Alkynyl modified polyamide/lignin shape memory composite material and preparation method thereof

Technical Field

The invention belongs to the technical field of bio-based functional materials, and particularly relates to an alkynyl modified polyamide/lignin shape memory composite material and a preparation method thereof.

Background

The shape memory material is an intelligent material, and after the material senses environmental change, the shape, position, strain and other mechanical parameters of the material are adjusted, and finally the material can be restored to an initial state. At present, shape memory polymer materials are focused on by researchers, and the materials are firstly proposed by Mather at 1940, and then the Mather is called as elastic memory. Shape Memory Polymers (SMP) can be categorized into thermally, optically, electrically, magnetically, and chemically induced shape memory polymers, depending on the mechanism of action. SMP has the advantages of small density, large recoverable deformation, low production cost, easy processing and forming, good printability, corrosion resistance and the like.

Lignin is a natural biomass polymer with reserve inferior to cellulose, is a byproduct of paper making and biorefinery industries, has huge yield, still does not fully exert use value, and needs high-value utilization. The main structural units of lignin are coumaryl alcohol, coniferyl alcohol and sinapyl alcohol, which are connected together through carbon-carbon bonds and ether bonds to form an amorphous hyperbranched structure. Lignin has various functional groups, and the ortho position of hydroxyl is a reaction site of lignin, which allows the introduction of a desired group into lignin, imparting a specific function. Therefore, the invention provides an alkynyl modified polyamide/lignin shape memory composite material and a preparation method thereof.

Disclosure of Invention

The invention aims to: the invention aims to solve the technical problem of providing an alkynyl modified polyamide/lignin shape memory composite material aiming at the defects of the prior art.

The invention also solves the technical problem of providing a preparation method of the alkynyl modified polyamide/lignin shape memory composite material.

In order to solve the first technical problem, the invention discloses an alkynyl modified polyamide/lignin shape memory composite material which is prepared from the following components in parts by weight: 10-50 parts of alkynyl modified lignin and 50-90 parts of modified polyamide shown in a formula I;

wherein n is more than or equal to 2 and less than or equal to 100.

In some embodiments, the shape retention of the composite is 85% to 99.2%; in some embodiments, the shape retention of the composite is.

In some embodiments, the shape recovery of the composite is 70% -95%; in some embodiments, the composite material has a shape recovery of 74% to 91%.

In some embodiments, the method of preparing the alkynylated modified lignin is: in alkaline alcohol solution, lignin, 3-acetylene aniline and formaldehyde react to obtain reaction liquid containing alkynyl modified lignin.

Wherein the lignin includes, but is not limited to, kraft lignin, organo lignin, alkali lignin, enzymatically hydrolyzed lignin, and lignin sulfate.

Wherein, the weight ratio of lignin, 3-acetylene aniline and formaldehyde is 20:3 to 5:0.5 to 1.5.

Wherein the alkaline alcohol solution is a mixed solution of sodium hydroxide and alcohol; the pH of the alkaline alcohol solution=12 to 13; the alcohol is ethanol; the volume ratio of alcohol to water in the alkaline alcohol solution is 3:4 to 10, preferably 3:7, preparing a base material; in the alkaline alcohol solution, the mass concentration of lignin in the mixed solution of lignin, 3-acetylene aniline and formaldehyde is below 25%.

Wherein the temperature of the reaction is 70-90 ℃; the reaction time is 3-5 h; the reaction is specifically reflux stirring for 3-5 h at 70-90 ℃.

And after the reaction is finished, regulating the pH value to be 3-4, precipitating, washing with water, filtering and drying to obtain the alkynyl modified lignin.

In some embodiments, the modified polyamide of formula I is prepared by: and (3) carrying out a first reaction in anhydrous N-methylpyrrolidone under the ice bath of diamine, 3-acetylene aniline, triethylamine and isophthaloyl dichloride, and carrying out a second reaction after heating to obtain a reaction solution containing the modified polyamide shown in the formula I.

Wherein the diamine is a diamine with 6 to 12 carbon atoms, including but not limited to 1, 6-hexamethylenediamine, 1, 9-nonylenediamine, 1, 10-decylenediamine and 1, 12-diaminododecane.

Wherein the dosage ratio of the diamine, the 3-acetylene aniline, the triethylamine and the isophthaloyl dichloride is 1g:0.1 to 0.4g: 2.3 mL:0.8 to 1g, preferably 1g:0.15 to 0.37g: 2.35-2.68 mL:0.85 g to 0.98g.

Wherein the dosage ratio of the anhydrous N-methyl pyrrolidone to the diamine is 10-13 mL:1g, preferably 10.69 to 12.17mL:1g.

Wherein the time of the first reaction is 10 to 50min, preferably 20 to 40min, and more preferably 30min.

Wherein the temperature of the second reaction is 40-80 ℃, preferably 50-70 ℃, and more preferably 60 ℃; the second reaction time is 1 to 2 hours, preferably 1.2 to 1.8 hours, and more preferably 1.5 hours.

In order to solve the second technical problem, the invention also discloses a preparation method of the alkynyl modified polyamide/lignin shape memory composite material.

In some embodiments, the preparation method comprises dissolving alkynyl modified lignin in a first solvent to obtain a first reaction solution, dissolving modified polyamide shown in a formula I in a second solvent to obtain a second reaction solution, uniformly mixing the first reaction solution and the second reaction solution, volatilizing the solvent to obtain a mixture, and curing the obtained mixture to obtain the alkynyl modified polyamide/lignin shape memory composite material.

Wherein the first solvent and the second solvent are each independently selected from hexafluoroisopropanol, tetrahydrofuran, or a combination of the two solvents.

The first solvent and the second solvent are used in an amount which ensures dissolution, and no other requirements exist; in some embodiments, the weight ratio of the alkynylated modified lignin to the first solvent is from 10 to 50: 30-400 parts; in some embodiments, the weight ratio of the modified polyamide represented by formula I to the second solvent is 50 to 90:300 to 500.

Wherein the curing temperature is 230-270 ℃, preferably 240-260 ℃, and more preferably 250 ℃; the curing time is 30-40 min.

According to the invention, a co-network structure (abbreviated as AB co-network structure) is formed between the alkynylated modified lignin and the modified polyamide shown in the formula I in the alkynylated modified polyamide/lignin shape memory composite material prepared by the method. The invention provides a new idea for preparing lignin AB co-network shape memory material. The structural characteristics of lignin are utilized, thermal crosslinking groups are introduced into the lignin through alkynyl modification, and the lignin is crosslinked with bio-based polyamide which also has the thermal crosslinking groups, so that an AB co-network of the material is obtained; AB co-network, can be through adjusting A, B two kinds of molecule chain segments's proportion, or adjust A, B two kinds of molecule chain segments's size of chain length, can conveniently adjust the transition temperature of material, different transformation phase's proportion, mechanical properties and shape memory performance, offer the technological reference for the development of bio-based intelligent material.

The beneficial effects are that: compared with the prior art, the invention has the following advantages:

1. the invention controls the molecular weight of the bio-based polyamide by adjusting the input proportion of the raw materials, and finally controls the switching temperature of the shape memory, so that the adjustability of the whole shape memory system is higher.

2. The lignin and the bio-based polyamide in the material are biomass resources, and the utilization rate of the biomass resources is very high. Lignin is combined with the synthesized bio-based polyamide to develop a shape memory material with excellent performance, which shows high-value utilization of biomass resources.

3. The invention fully utilizes the structural characteristics of rich lignin functional groups, obtains the thermally-crosslinkable modified lignin through derivatization modification, and the crosslinking temperature is matched with a material processing temperature window.

4. The composite material provided by the invention forms a co-network structure, has lignin-polyamide cross-linked network phase and polyamide glass transition temperature, and has better high-temperature shape memory performance.

Drawings

The foregoing and/or other advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings and detailed description.

FIG. 1 biobased polyamide hydrogen profiling; (a) biobased polyamide 1, (b) biobased polyamide 2.

Rheological analysis of the shape memory material of fig. 2; (a) A biobased polyamide 1 and a modified lignin system thereof, and (b) a biobased polyamide 2 and a modified lignin system thereof.

Shape memory behavior of the material of FIG. 3; (a) example 2, (b) example 3, (c) example 4, (d) example 5.

FIG. 4 is a graph showing the shape memory properties of the material of example 3. (a) Is an original shape, (b) is a temporary shape, (c-d) is a shape recovery process, and (e) is a final recovery shape.

Fig. 5 and 6 are graphs showing the shape memory properties of the materials of comparative examples 2 and 3, respectively. (a) an original shape, (b) a temporary shape.

FIG. 7 infrared analysis of modified lignin.

Detailed Description

The experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials, unless otherwise specified, are commercially available.

Example 1:

(1) Preparation of biobased modified Polyamide 1 (examples 1-1)

1, 10-decanediamine (4.111 g), 3-ethynylaniline (1.487 g), triethylamine (11 mL) were dissolved in an anhydrous NMP solution (50 mL). Then isophthaloyl dichloride (4 g) was added thereto, and the mixture was reacted in an ice bath for 30 minutes. After removing the ice bath, the reaction was carried out at 60℃for 1.5 hours. After the reaction is finished, the product is vigorously stirred in water, washed, filtered and dried to obtain the bio-based polyamide 1.

(2) Preparation of biobased modified Polyamide 2 (examples 1-2)

1, 10-decanediamine (4.673 g), 3-ethynylaniline (0.728 g), triethylamine (11 mL) were dissolved in an anhydrous NMP solution (50 mL). Then isophthaloyl dichloride (4 g) was added thereto, and the mixture was reacted in an ice bath for 30 minutes. After removing the ice bath, the reaction was carried out at 60℃for 1.5 hours. And after the reaction is finished, the product is vigorously stirred in water, washed, filtered and dried to obtain the bio-based polyamide 2.

The obtained biobased modified polyamide 1 and biobased modified polyamide 2 were subjected to hydrogen spectrum analysis, and the results are shown in FIG. 1. Two organismsOf base-modified polyamides ¹ No obvious hetero peak appears in the H-NMR spectrum, which indicates that the purity of the obtained bio-based modified polyamide is higher. The appearance of a new peak around 4.25ppm in the figure can confirm that the functional alkynyl group was successfully introduced. According to ¹ The number of peaks in the H-NMR spectrum and the integrated area ratio can be estimated that the basic composition ratio of the bio-based modified polyamide is not much different from the raw material input ratio.

Example 2: preparation of alkynyl modified Polyamide 1/lignin shape memory composite (5:5)

(1) 5g of kraft lignin was taken and dissolved in a water (70 mL) -ethanol (30 mL) mixed solution. NaOH was added to adjust pH=13 to dissolve the mixture, 3-ethynylaniline (0.8 g) was added thereto, and formaldehyde solution (0.4 mL) was added dropwise thereto, followed by stirring under reflux at 90℃for 4 hours. After the completion, the pH of the solution was adjusted to 3 to precipitate. Washing with ultrapure water, filtering, and vacuum drying at 65 ℃ for 24 hours to obtain the modified lignin.

(2) 5g of modified lignin and 5g of bio-based polyamide 1 are respectively dissolved in 20ml and 20ml of hexafluoroisopropanol, and after the solutions are uniformly mixed, the solvent is volatilized and ground into powder.

(3) And filling the powder into a mould, and keeping the mould at the high temperature of 250 ℃ for 30min, and curing to obtain the shape memory material.

Example 3: preparation of alkynyl modified Polyamide 2/lignin shape memory composite (5:5)

(2) Taking 5g of modified lignin and dissolving 5g of bio-based polyamide 2 in 20ml and 20ml of hexafluoroisopropanol respectively; mixing the above solutions, volatilizing the solvent, and grinding into powder.

Example 4: preparation of alkynyl modified Polyamide 1/lignin shape memory composite (1:9)

(2) 1g of modified lignin and 9g of bio-based polyamide 1 are respectively dissolved in 4ml and 36ml of hexafluoroisopropanol; mixing the above solutions, volatilizing the solvent, and grinding into powder.

Example 5: preparation of alkynyl modified Polyamide 2/lignin shape memory composite (1:9)

(2) 1g of modified lignin and 9g of bio-based polyamide 2 are respectively dissolved in 4ml and 36ml of hexafluoroisopropanol; mixing the above solutions, volatilizing the solvent, and grinding into powder.

Comparative example 1: unmodified lignin+unmodified polyamide

(1) 1, 10-decanediamine (4.111 g) and triethylamine (11 mL) were dissolved in an anhydrous NMP solution (50 mL). Then isophthaloyl dichloride (4 g) was added thereto, and the mixture was reacted in an ice bath for 30 minutes. After removing the ice bath, the reaction was carried out at 60℃for 1.5 hours. After the reaction is finished, the product is vigorously stirred in water, washed, filtered and dried to obtain the unmodified polyamide.

(2) Taking 5g of kraft lignin and dissolving 5g of unmodified polyamide in 20ml and 20ml of hexafluoroisopropanol respectively; mixing the above solutions, volatilizing the solvent, and grinding into powder.

Comparative example 2: alkynyl modified lignin+unmodified polyamide

(1) 5g of kraft lignin was taken in a mixed solution of water (70 mL) -ethanol (30 mL). NaOH was added to adjust pH=13 to dissolve the mixture, 3-ethynylaniline (0.8 g) was added thereto, and formaldehyde solution (0.4 mL) was added dropwise thereto, followed by stirring under reflux at 90℃for 4 hours. After the completion, the pH of the solution was adjusted to 3 to precipitate. Washing with ultrapure water, filtering, and vacuum drying at 65 ℃ for 24 hours to obtain the modified lignin.

(2) Taking 5g of modified lignin and 5g of unmodified polyamide to be respectively dissolved in 20ml and 20ml of hexafluoroisopropanol; mixing the above solutions, volatilizing the solvent, and grinding into powder.

Comparative example 3: unmodified lignin + modified polyamides

(1) Taking 5g of kraft lignin and 5g of bio-based polyamide 1, respectively dissolving in 20ml and 20ml of hexafluoroisopropanol; mixing the above solutions, volatilizing the solvent, and grinding into powder.

(2) And filling the powder into a mould, and keeping the mould at the high temperature of 250 ℃ for 30min, and curing to obtain the shape memory material.

Example 6: detection of

(1) Rotary rheometer

The rheological properties of the mixed powders obtained in step (2) in examples 2 to 5, as well as the rheological properties of the biobased polyamides 1, 2 in example 1, were characterized by means of a rotary rheometer under an air atmosphere.

As can be seen from FIG. 2, in the bio-based polyamide 1/modified lignin system, G' also increases with increasing modified lignin content. The mixed powder obtained in step (2) of example 2 has a faster stability of G' than that of example 4. This is due to the introduction of alkynyl groups in the modified lignin. During curing, the alkynyl groups of lignin and the alkynyl groups of bio-based polyamide 1 cross-link each other and self-cross-link. This rule is also true in biobased polyamide 2/modified lignin systems. It was demonstrated that the mixed powder obtained in step (2) of examples 2 to 5 was capable of forming a crosslinked network at 250 ℃.

(2) Shape memory test

Shape memory performance was tested using a dynamic mechanical analyzer (TA Instrument 2980). The sample was heated up at a heating rate of 10 c/min in the range of 60 to 150 c. The sample adopts a four-step program on a DMA instrument, and the strain, the stress and the temperature are relatively recorded under a control force mode that the pretightening force is 0.0001N: (1) Isothermal holding of the sample at 150 ℃ for 5 minutes, and stretching deformation with fixed stress; (2) Rapidly cooling to 60 ℃, maintaining constant stress at 60 ℃ for 5 minutes, and fixing temporary strain; (3) Removing the applied stress and maintaining at 60 ℃ for 5 minutes; (4) Rapidly reheating to 150 ℃, maintaining at 150 ℃ for 5 minutes, and recovering to the original strain.

Wherein the shape fixation ratio (R _f ) And shape recovery rate (R) _r ) Is the most important parameter describing shape memory performance. Shape fixation ratio (R) _f ) And shape recovery rate (R) _r ) Is the most important parameter describing shape memory performance. When the measurement is performed in the stretching mode, R _f And R is _r Is the most important parameter.

Wherein ε is ₀ ，ε _1，load ，ε ₁ And epsilon _0，rec The initial strain, the temporary strain after loading, the temporary strain after unloading, and the recovered strain, respectively. All of this can be measured directly from the DMA curve.

From FIG. 3 and Table 1, it can be seen that the cured sample has shape memory properties, R _f 85% -99.2%, R _r 70% -95%, which means that the sample material has a good shape retention (R _f ) And shape recovery rate (R) _r )。

TABLE 1

Sample of	R _f (％)	R _r (％)
			Example 2	92.4	74.3
Example 3	86.4	78.1
			Example 4	99.0	90.1
Example 5	99.2	86.3

(3) Qualitative characterization of shape memory behavior

And (3) placing the rectangular sample in an oven with the temperature of 150 ℃, placing for 5min, applying external force to deform, taking out, completely cooling at room temperature, crystallizing, shaping, and removing the force at the moment. And (3) under the condition of no external force, placing the deformed sample into an oven with the temperature of 150 ℃ for 5min for shape recovery.

Taking the example 3 (fig. 4 a) as an example, when heated above Tg (150 ℃), the microscopic brownian motion of the reversible phase molecular chains is exacerbated while the stationary phase is still in a cured state, with the molecular chains being bound, the material is transformed from glassy to rubbery. At this time, an external force is applied to the sample to deform it. The reversible phase solidifies after cooling under the hold of an external force, and a new stable shape, i.e. a temporary shape, is obtained after releasing the external force (fig. 4 b). The shape at this time is maintained by the reversible phase with its molecular chains oriented frozen along the direction of the external force and the stationary phase in a high stress deformation state. When the temporary shape is heated to a shape recovery temperature of 150 ℃, the molecular chain movement ability is recovered, the orientation is released under the recovery stress of the stationary phase, and the thermodynamic equilibrium state is gradually reached (fig. 4 cde). To this end, the material macroscopically returns to its original shape (fig. 4 e) and only 5s are needed for the return.

Taking the samples of comparative example 2 (FIG. 5 a) and comparative example 3 (FIG. 6 a) as examples, when heated to a temperature above Tm (150 ℃ C.), an external force is applied to the sample to deform the sample, however, the material portion is transformed into a viscous flow state, and the original shape thereof is destroyed by the external force (FIGS. 5b and 6 b). In contrast, in the sample of comparative example 1, lignin and polyamide are not modified, and the polyamide is amorphous with small molecular weight, so that a network structure cannot be formed, and the sample cannot be formed into a spline.

(4) Infrared characterization and elemental analysis

The infrared spectrum is collected by a Thermo Nicolet 6700 spectrometer (Thermo Fischer Scientific, waltham, mass., USA) in the range of 500-4500cm ^-1 Scanning for 16 times with spectral resolution of 2cm ^-1 。

As can be seen from fig. 7, the modified lignin showed 4 new peaks in infrared spectrum compared with kraft lignin. Wherein 3286cm ^-1 The new peak at is the C-H stretching vibration of-C≡C-H due to the introduction of alkynyl groups in the modified lignin; 780cm ^-1 、687cm ^-1 And 650cm ^-1 The new peak at this point is the meta-disubstituted C-H out-of-plane bending vibration of the benzene ring due to the participation of 3-ethynylaniline in the modification wherein alkynyl groupsConjugation with the benzene ring results in displacement to the lower position.

From table 2, it can be seen that the modified lignin has an increased N content compared to kraft lignin, demonstrating the successful introduction of the desired groups.

TABLE 2

The invention provides an alkynyl modified polyamide/lignin shape memory composite material and a method for preparing the same, and the method for realizing the technical scheme is a plurality of methods and paths, the above is only a preferred embodiment of the invention, and it should be pointed out that a plurality of improvements and modifications can be made by one of ordinary skill in the art without departing from the principle of the invention, and the improvements and modifications are also considered as the protection scope of the invention. The components not explicitly described in this embodiment can be implemented by using the prior art.

Claims

1. The alkynyl modified polyamide/lignin shape memory composite material is characterized by being prepared from the following components in parts by weight: 10-50 parts of alkynyl modified lignin and 50-90 parts of modified polyamide shown in a formula I;

wherein n is more than or equal to 2 and less than or equal to 100.

2. The alkynylated modified polyamide/lignin shape memory composite material according to claim 1, wherein the composite material has a shape retention of 85% to 99.2%.

3. The alkynylated modified polyamide/lignin shape memory composite material according to claim 1, wherein the composite material has a shape recovery rate of 70% -95%.

4. The alkynylated modified polyamide/lignin shape memory composite material according to claim 1, wherein the composite material has a shape recovery rate of 74% -91%.

5. The alkynylated modified polyamide/lignin shape memory composite material according to any one of claims 1 to 4, wherein the preparation method of the alkynylated modified lignin is: in alkaline alcohol solution, lignin, 3-acetylene aniline and formaldehyde react to obtain reaction liquid containing alkynyl modified lignin.

6. The alkynylated modified polyamide/lignin shape memory composite material according to claim 5, wherein the lignin, 3-ethynylaniline and formaldehyde weight ratio is 20: 3-5: 0.5 to 1.5.

7. The alkynylated modified polyamide/lignin shape memory composite material according to claim 5, wherein the pH of the alkaline alcoholic solution is=12-13.

8. The alkynylated modified polyamide/lignin shape memory composite material according to claim 5, wherein the alcohol is ethanol.

9. The alkynylated modified polyamide/lignin shape memory composite material according to claim 5, wherein the volume ratio of alcohol to water in the alkaline alcohol solution is 3: 4-10.

10. The alkynylated modified polyamide/lignin shape memory composite material according to claim 5, wherein in the alkaline alcohol solution, the mass concentration of lignin in the mixed solution of lignin, 3-acetylene aniline and formaldehyde is below 25%.

11. The alkynylated modified polyamide/lignin shape memory composite material according to claim 5, wherein the temperature of the reaction is 70-90 ℃.

12. The alkynylated modified polyamide/lignin shape memory composite material according to claim 5, wherein the reaction time is 3-5 hours.

13. The alkynylated modified polyamide/lignin shape memory composite material according to any one of claims 1 to 4, wherein the preparation method of the modified polyamide shown in formula I is: and (3) carrying out a first reaction in anhydrous N-methylpyrrolidone under the ice bath of diamine, 3-acetylene aniline, triethylamine and isophthaloyl dichloride, and carrying out a second reaction after heating to obtain a reaction solution containing the modified polyamide shown in the formula I.

14. The alkynylated modified polyamide/lignin shape memory composite material according to claim 13, wherein the diamine is a diamine having 6 to 12 carbon atoms.

15. The alkynylated modified polyamide/lignin shape memory composite material according to claim 13, wherein the diamine is any one or a combination of several of 1, 6-hexamethylenediamine, 1, 9-nonanediamine, 1, 10-decanediamine and 1, 12-diaminododecane.

16. The alkynylated modified polyamide/lignin shape memory composite material according to claim 13, wherein the usage ratio of diamine, 3-ethynylaniline, triethylamine and isophthaloyl chloride is 1g: 0.1-0.4 g: 2-3 mL: 0.8-1 g.

17. The alkynylated modified polyamide/lignin shape memory composite material according to claim 13, wherein the usage ratio of diamine, 3-ethynylaniline, triethylamine and isophthaloyl chloride is 1g:0.15 to 0.37g: 2.35-2.68 mL:0.85 to 0.98g.

18. The alkynylated modified polyamide/lignin shape memory composite material according to claim 13, wherein the dosage ratio of anhydrous N-methylpyrrolidone to diamine is 10-13 ml:1g.

19. The alkynylated modified polyamide/lignin shape memory composite material according to claim 13, wherein the dosage ratio of anhydrous N-methylpyrrolidone to diamine is 10.69 to 12.17ml:1g.

20. The alkynylated modified polyamide/lignin shape memory composite material according to claim 13, wherein the time of the first reaction is 10-50 min.

21. The alkynylated modified polyamide/lignin shape memory composite material according to claim 13, wherein the time of the first reaction is 20-40 min.

22. The alkynylated modified polyamide/lignin shape memory composite material according to claim 13, wherein the time of the first reaction is 30 minutes.

23. The alkynylated modified polyamide/lignin shape memory composite material according to claim 13, wherein the temperature of the second reaction is 40-80 ℃.

24. The alkynylated modified polyamide/lignin shape memory composite material according to claim 13, wherein the temperature of the second reaction is 50-70 ℃.

25. The alkynylated modified polyamide/lignin shape memory composite material according to claim 13, wherein the temperature of the second reaction is 60 ℃.

26. The alkynylated modified polyamide/lignin shape memory composite material according to claim 13, wherein the second reaction time is 1-2 hours.

27. The alkynylated modified polyamide/lignin shape memory composite material according to claim 13, wherein the time of the second reaction is 1.2-1.8 h.

28. The alkynylated modified polyamide/lignin shape memory composite material according to claim 13, wherein the time of the second reaction is 1.5h.

29. The method for preparing the alkynyl modified polyamide/lignin shape memory composite material according to any one of claims 1 to 13, which is characterized in that alkynyl modified lignin is dissolved in a first solvent to obtain a first reaction solution, modified polyamide shown in a formula I is dissolved in a second solvent to obtain a second reaction solution, the first reaction solution and the second reaction solution are uniformly mixed, the solvent is removed by volatilization to obtain a mixture, and the obtained mixture is solidified to obtain the alkynyl modified polyamide/lignin shape memory composite material.

30. The method of claim 29, wherein the first solvent and the second solvent are each independently selected from hexafluoroisopropanol, tetrahydrofuran, or a combination of the two solvents.

31. The method of claim 29, wherein the curing temperature is 230-270 ℃.

32. The method of claim 29, wherein the curing temperature is 240-260 ℃.

33. The method of claim 29, wherein the curing temperature is 250 ℃.

34. The method of claim 29, wherein the curing time is 30-40 minutes.