CN112321843A - Lignin-based polycarboxylic acid and preparation method thereof - Google Patents
Lignin-based polycarboxylic acid and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a lignin-based polycarboxylic acid and a preparation method thereof, S10, mixing lignin powder and cyclic anhydride powder in a molar ratio of 1:1.0, 1:1.2, 1:1.4, 1:1.6, 1:1.8 and 1: 2.0; s20, pouring the 6 groups of mixtures into 4 100mL zirconia ball milling tanks of a planetary ball mill respectively, and carrying out mechanochemical modification in groups; s30, adding potassium hydroxide which accounts for 3-5 wt% of the total weight of the mixture into each zirconia ball milling tank to serve as an alkaline catalyst; s40, the operation mode of the planetary ball mill is bidirectional, the frequency is 50Hz, and the rotation direction is changed once every 15 minutes; s50, ball-milling for 100-140 minutes, and pouring out the cyclic anhydride modified lignin-based polycarboxylic acid from the planetary ball mill; and S60, removing residual acid and a basic catalyst and drying. According to the invention, the chemical modification is carried out on the lignin under the condition of no solvent by a high-energy ball milling method, the reaction condition of the mechanochemical modification of the lignin is simpler, and the reaction efficiency is higher.
Description
Technical Field
The invention belongs to the technical field of lignin materials, and particularly relates to lignin-based polycarboxylic acid and a preparation method thereof.
Background
In the daily life of people, fossil-based products are ubiquitous and have huge consumption, which causes serious problems of environmental pollution, resource shortage and the like. The increasing shortage of fossil resources and the biodegradability of fossil-based products make the search for renewable and biodegradable resources to replace fossil-based products an urgent problem to be solved urgently. Among them, natural high molecular compounds are derived from the nature, are easily biodegradable, and are one of the most ideal resources to replace fossil-based products. Lignocellulose is the biomass material with the most extensive sources in nature and mainly comprises three components of cellulose, hemicellulose and lignin. Among them, lignin is the second most abundant biomass material next to cellulose, and is the only degradable biomass material in nature that can provide aromatic groups, and is a promising alternative resource for fossil-based products.
Lignin is a three-dimensional net-shaped phenolic natural high molecular polymer with a complex structure, the annual output is about 2000 hundred million tons, and the lignin is a main byproduct in pulping, papermaking and biorefinery industries, wherein most of the lignin is used as fuel for direct combustion, and only about 3 percent of the very small amount of lignin is recovered and utilized. The basic structure of the lignin is a phenylpropane monomer, and the lignin is mainly composed of 3 phenylpropane structures: (1) p-hydroxyphenyl propane monomer; (2) guaiacyl propane monomer; (3) the molecular structure of syringyl propane monomer is shown in figure 1, and the phenylpropane structure in the 3 is linked through C-C bond and ether bond according to the mechanism of continuous dehydrogenation polymerization to form the three-dimensional reticular polyphenol compound structure of lignin. Therefore, unlike cellulose, which can be represented by a regular chemical formula, lignin generally has a part of molecular structure deduced from the test results, see fig. 2, and the connection mode of phenylpropane monomers in the lignin structure includes β -O-4, α -O-4, 4-O-5, β -1, β -5, β - β, 5-5, etc., wherein β -O-4 is the most predominant connection mode in lignin.
Due to the complex three-dimensional network structure of the lignin, the reactivity and accessibility of the lignin are greatly limited, so that the high-added-value application development of the lignin is difficult. However, the lignin structure contains a large number of various functional groups, such as hydroxyl, carbonyl, carboxyl, methoxyl, conjugated double bonds, aromatic groups, carbon-carbon double bonds and the like, and provides diversity and basis for the modification research of lignin. Through chemical modification methods such as phenolization, esterification, sulfonation, epoxidation and the like, the reaction activity of lignin is improved, so that the high-added-value application prospect of the lignin material is expanded. However, chemical modification is generally performed in a dissolving medium, and the complex three-dimensional network structure of lignin makes the lignin have extremely low solubility in a solution, and the reaction conditions are usually harsh (high temperature and high pressure), the reaction time is long, the reaction efficiency and the conversion rate are low, and the problems commonly existing in the chemical modification process of lignin prompt us to find a green, efficient and solvent-free lignin modification method.
Mechanical force introduces mechanical energy into a reaction system through different action forms (including compression, impact, shearing, grinding and the like), on one hand, the reactants are physically changed (particle refinement) through mechanical ball milling, and on the other hand, chemical bonds of the reactants are broken through the introduced mechanical energy to trigger chemical change, so that the reactivity of the reactants is improved, and chemical reaction is triggered and accelerated. The main features of mechanochemistry can be summarized as the following three points: (1) initiating a chemical reaction of the substance without adding any solvent; (2) the mechanochemical reaction can effectively reduce by-products and toxic waste materials generated by the reaction; (3) mechanochemical reactions take less time than ordinary chemical reactions. Therefore, the invention provides the method for carrying out efficient and environment-friendly chemical modification on the lignin material by using a mechanochemical method, can well avoid the influence and limitation of low solubility of the lignin on the chemical modification, and has very important practical significance for exploring the high-added-value application of the lignin.
Disclosure of Invention
In view of the above, the invention realizes efficient mechanochemical modification of lignin in a short time by a high-energy ball milling method under the condition of no solvent, improves the reaction activity of lignin, improves the compatibility between lignin and other materials, and is convenient for commercial development and utilization of lignin-based composite materials.
In order to achieve the above object, the present invention provides a method for preparing lignin-based polycarboxylic acid, comprising the steps of:
s10, mixing the lignin powder and the cyclic anhydride powder in a molar ratio of 1:1.0, 1:1.2, 1:1.4, 1:1.6, 1:1.8 and 1: 2.0;
s20, pouring the 6 groups of mixtures into 4 100mL zirconia ball milling tanks of a planetary ball mill respectively, and carrying out mechanochemical modification in groups;
s30, adding potassium hydroxide which accounts for 3-5 wt% of the total weight of the mixture into each zirconia ball milling tank to serve as an alkaline catalyst;
s40, the operation mode of the planetary ball mill is bidirectional, the frequency is 50Hz, and the rotation direction is changed once every 15 minutes;
s50, ball-milling for 100-140 minutes, and pouring out the cyclic anhydride modified lignin-based polycarboxylic acid from the planetary ball mill;
and S60, removing residual acid and a basic catalyst and drying.
Preferably, the cyclic anhydride is succinic anhydride.
Preferably, the cyclic anhydride is maleic anhydride.
Preferably, 16 zirconia balls with the diameter of 10mm and 100 zirconia balls with the diameter of 6mm are arranged in each zirconia ball-milling tank as ball-milling media.
Preferably, the lignin is of the organosolv type.
Preferably, the step of drying after removing residual acid and basic catalyst by S60 comprises the following steps:
s61, removing residual cyclic anhydride by using distilled water, and rinsing for 2 times;
s62, neutralizing the mixed solution by using a dilute hydrochloric acid solution with the concentration of 0.5M, and removing the alkaline catalyst;
s63, rinsing the mixture for 2 times by using distilled water, and taking out a filter cake after filtering;
s64, drying in vacuum at 60-80 ℃ for 12 hours.
In view of the above object, the present invention also provides a lignin-based polycarboxylic acid prepared by the above preparation method, wherein lignin and cyclic anhydride are mixed in a molar ratio of 1:1.0, 1:1.2, 1:1.4, 1:1.6, 1:1.8 or 1:2.0, and esterification reaction is performed on the lignin and the cyclic anhydride to obtain the lignin-based polycarboxylic acid.
The invention has the beneficial effects that: the method is characterized in that efficient and environment-friendly chemical modification is carried out on lignin by a mechanochemical method through high-energy ball milling under the condition of no solvent, and the lignin is chemically modified by the mechanochemical method through the high-energy ball milling under the condition of no solvent. In the ball milling process, mechanical force induces the chemical structure of lignin to change, ether bonds and C-C bonds in the lignin are broken under the action of mechanical force, so that the molecular weight of the lignin is reduced; a large number of hydroxyl groups in the lignin are excited into an activated state, so that the lignin is more easily substituted by an affinity compound, and the reactivity and accessibility of the lignin are improved. Therefore, compared with the traditional solution reaction, the reaction condition of the mechanical and chemical modification of the lignin is simpler, the reaction efficiency is higher, and the difficult problem that the lignin is difficult to develop and utilize due to low reaction activity at the present stage is effectively solved.
Therefore, the invention discloses the rules of the mechanochemical modification by researching the process of the mechanochemical modification of the lignin and clarifies the influencing factors in the mechanochemical reaction process so as to realize the efficient mechanochemical modification of the lignin in a short time by a high-energy ball milling method under the condition of no solvent, improve the reaction activity of the lignin, improve the compatibility between the lignin and other materials and facilitate the commercial development and utilization of lignin-based composite materials. The method not only makes full use of lignin resources, but also has very important practical significance for papermaking pollution discharge, environmental management and energy utilization in China.
Drawings
In order to make the object, technical scheme and beneficial effect of the invention more clear, the invention provides the following drawings for explanation:
FIG. 1 is a molecular structure diagram of 3 phenylpropanes of lignin;
FIG. 2 is a schematic diagram of the chemical structure and connection of a part of coniferous lignin;
FIG. 3 is a flow chart illustrating the steps of a method for preparing a lignin-based polycarboxylic acid according to an embodiment of the present invention;
FIG. 4 is a schematic illustration of an esterification reaction of lignin with a cyclic anhydride according to an embodiment of the present invention;
FIG. 5 is an IR spectrum of a lignin-based polycarboxylic acid modified with maleic anhydride in accordance with the present invention and unmodified lignin of the prior art;
FIG. 6 is an IR spectrum of a lignin-based polycarboxylic acid modified with unmodified lignin of the prior art and succinic anhydride of an embodiment of the present invention;
FIG. 7 is a nuclear magnetic resonance image of a lignin-based polycarboxylic acid modified with maleic anhydride in the example of the present invention and unmodified lignin of the prior art;
FIG. 8 is NMR spectra of unmodified lignin of the prior art and succinic anhydride modified lignin-based polycarboxylic acids of the examples of the present invention.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
Referring to fig. 3, the present invention provides a method for preparing lignin-based polycarboxylic acid, comprising the steps of:
s10, mixing the lignin powder and the cyclic anhydride powder in a molar ratio of 1:1.0, 1:1.2, 1:1.4, 1:1.6, 1:1.8 and 1: 2.0;
s20, pouring the 6 groups of mixtures into 4 100mL zirconia ball milling tanks of a planetary ball mill respectively, and carrying out mechanochemical modification in groups;
s30, adding potassium hydroxide which accounts for 3-5 wt% of the total weight of the mixture into each zirconia ball milling tank to serve as an alkaline catalyst;
s40, the operation mode of the planetary ball mill is bidirectional, the frequency is 50Hz, and the rotation direction is changed once every 15 minutes;
s50, ball-milling for 100-140 minutes, and pouring out the cyclic anhydride modified lignin-based polycarboxylic acid from the planetary ball mill;
and S60, removing residual acid and a basic catalyst and drying.
In a specific embodiment, the cyclic anhydride is succinic anhydride or maleic anhydride. 16 zirconia balls with the diameter of 10mm and 100 zirconia balls with the diameter of 6mm are arranged in each zirconia ball-milling tank as ball-milling media. The lignin is organic solvent type.
S60 removing residual acid and basic catalyst and drying, comprising the following steps:
s61, removing residual cyclic anhydride by using distilled water, and rinsing for 2 times;
s62, neutralizing the mixed solution by using a dilute hydrochloric acid solution with the concentration of 0.5M, and removing the alkaline catalyst;
s63, rinsing the mixture for 2 times by using distilled water, and taking out a filter cake after filtering;
s64, drying in vacuum at 60-80 ℃ for 12 hours.
Under the condition of high-energy ball milling, sodium hydroxide is selected as an alkaline catalyst, so thatSynthesizing lignin-based polycarboxylic acid by taking organic solvent type lignin (Organosolv lignin) and cyclic anhydride (succinic anhydride and maleic anhydride) as raw materials, breaking an acyl-oxygen bond in the cyclic anhydride under the action of mechanical force, replacing a hydroxyl group on the lignin by esterification reaction to generate the lignin-based polycarboxylic acid, and characterizing the chemical structure and a representative functional group of the lignin-based polycarboxylic acid. Investigating the influence of reaction conditions such as raw material stoichiometric ratio, ball milling time and the like on reaction conversion rate, optimizing preparation process and reaction conditions, adopting characterization methods such as infrared spectroscopy (FT-IR), Nuclear Magnetic Resonance (NMR) and the like to characterize chemical structure and molecular weight of the product, and using the product31And (3) determining the contents of alcoholic hydroxyl, phenolic hydroxyl and carboxyl in the lignin by a P-NMR method. The esterification reaction of lignin with cyclic anhydride is shown in figure 4.
Raw materials: organosolv Lignin (OL) is available from American Science and Technology co, chicago, il, Succinic Anhydride (SA) and Maleic Anhydride (MA) both purchased from Alfa Aesar (Ward Hill, MA).
The instrument comprises the following steps: planetary ball mill PQ-N04 (geared 4 station, Across International).
The method for modifying the lignin by mechanochemical esterification comprises the following steps: firstly, mixing lignin powder and succinic anhydride powder in a molar ratio of 1:1.0, 1:1.2, 1:1.4, 1:1.6, 1:1.8 and 1:2.0, respectively putting the 6 groups of uniformly mixed samples into a zirconia ball milling tank with the volume of 100mL, wherein potassium hydroxide accounting for 3-5 wt% of the total weight of the mixture is added as an alkaline catalyst, and no liquid solvent is added. Each zirconia ball-milling jar contained 16 zirconia balls with a diameter of 10mm and 100 zirconia balls with a diameter of 6mm as ball-milling media. The operation mode of the planetary ball mill is bidirectional operation, the speed is set to 50Hz, and the rotation direction is changed every 15 minutes. And after the reaction is finished, taking out the mixture, removing residual succinic anhydride by using distilled water at about 60 ℃, rinsing for 2 times, neutralizing the mixed solution by using a dilute hydrochloric acid solution with the concentration of 0.5M, removing the alkaline catalyst, rinsing for 2 times by using distilled water, filtering, taking out a filter cake, drying for 12 hours in vacuum at 60-80 ℃, and finally collecting to obtain the succinic anhydride modified lignin-based polycarboxylic acid. Meanwhile, mixing lignin powder and maleic anhydride powder in a molar ratio of 1:1.0, 1:1.2, 1:1.4, 1:1.6, 1:1.8 and 1:2.0, and carrying out reaction according to the steps to obtain the maleic anhydride modified lignin-based polycarboxylic acid.
In order to optimize modification conditions and determine ball milling time, a mixture of lignin and maleic anhydride is ball milled for 180 minutes, samples are taken every 10 minutes in the reaction process, the hydroxyl value, the carboxyl value and the particle size of lignin particles of a reaction product are respectively tested, and the conversion degree of the esterification reaction and the change of the lignin particle size along with the ball milling time are compared. Referring to Table 1, the hydroxyl value of lignin gradually decreased from 5.38mmol/g to 2.47mmol/g and the carboxyl value increased from 0.37mmol/g to 1.52mmol/g during the ball milling time increased to 100 min, and the decrease and increase were obvious. When the ball milling time is increased from 100 minutes to 180 minutes, the change trend of the hydroxyl value and the carboxyl value tends to be smooth, the reduction amplitude of the hydroxyl value is within 0.1, and the increase amplitude of the carboxyl value is within 0.05, and almost no change exists. During the ball milling process of 3 hours, the particle size of the lignin is reduced from the initial 48.5 μm to 18.6 μm after the ball milling process is carried out for 180 minutes, and the lignin particles are obviously refined. After the ball milling time is increased to 100 minutes, the reduction of the lignin particle size tends to be smooth and is maintained at about 18 micrometers, when the ball milling time is 140 minutes, the lignin particle size reaches the minimum value of 17.8 micrometers, and then partial agglomeration of the lignin particles can occur in the ball milling process, so that the lignin particle size is slightly increased, and after the reaction efficiency and the reaction energy consumption are comprehensively considered, the more suitable ball milling time is 100-140 minutes.
TABLE 1 Effect of different ball milling times on lignin hydroxyl number and particle size
The physical and chemical properties of the modified lignin-based polycarboxylic acid are as follows:
the lignin before and after modification was subjected to KBr pellet processing and infrared spectroscopy (FT-IR) analysis, and the results are shown in FIGS. 5 and 6. All samples were at 3400cm-1A wide characteristic peak appears at the position, which belongs to the stretching vibration of hydroxyl O-H in lignin. The sample is at 2940cm-1The characteristic peak shows the C-H stretching vibration of methyl and methylene in the lignin. At 1600--1The vibration of the benzene ring skeleton in the lignin is proved by the characteristic peak band in the range. Compared with unmodified lignin, the modified lignin polycarboxylic acid is 1740cm-1The peak is marked with characteristic peaks (ester bond, absorption peak of phenolic acid) caused by stretching vibration of carbonyl group formed after reaction of lignin and cyclic anhydride. Comparing FIGS. 5 and 6, it can be seen that the maleic anhydride-modified lignin polycarboxylic acid is at 1640cm-1A weak absorption peak is generated, and the absorption peak is caused by stretching vibration of carbon-carbon double bonds C ═ C in maleic anhydride. 1100 to 1300cm-1The absorption peak band between the two bands belongs to the stretching vibration of C-C, C-O, C ═ O in the lignin sample.
Experimental results show that the acyl-oxygen bonds of the cyclic anhydride are totally broken in the high-speed ball milling process through mechanochemical modification, and the excited cyclic anhydride replaces hydroxyl groups on lignin through esterification reaction to form lignin-based polycarboxylic acid. Firstly, ball milling can cause partial degradation of lignin, and promotes accessibility and reactivity of functional groups of the lignin; second, mechanical breaking of chemical bonds results in the formation of more reactive species (radicals or ions). Therefore, the main reason for the chemical reaction is that the hydroxyl groups in the lignin increase the accessibility and reactivity of these functional groups during ball milling due to mechanical force induction, making them more susceptible to esterification with cyclic anhydrides.
In order to better determine the hydroxyl value of lignin and the reaction efficiency of esterification reaction, the invention adopts a nuclear magnetic resonance phosphorus spectrum method (31P NMR) to effectively determine the hydroxyl value of lignin before and after modification, wherein the NMR phosphorus spectra of lignin before and after modification are shown in FIGS. 7 and 8, and are calculated by softwareThe hydroxyl number of the modified lignin-based polycarboxylic acids at different stoichiometric ratios is shown in table 2. The hydroxyl groups in lignin are mainly classified into three main groups: alcoholic hydroxyl group (145.7-150.0ppm) on aliphatic carbon chain, phenolic hydroxyl group (136.6-144.7ppm) on benzene ring and carboxyl hydroxyl group (133.6-136.6ppm) in carboxyl. The signal intensity of both the alcoholic hydroxyl group and the phenolic hydroxyl group of the maleic anhydride-modified lignin-based polycarboxylic acid was reduced to a different extent compared to the unmodified lignin (control). Wherein, the hydroxyl value of the alcoholic hydroxyl group is reduced from unmodified 2.35mmol/g to modified 0.51-0.35mmol/g, and about 85 percent of the alcoholic hydroxyl group participates in the reaction; while the phenolic hydroxyl groups are reduced from unmodified 3.03mmol/g to modified 1.92-2.23mmol/g, and about 31 percent of the phenolic hydroxyl groups are reacted. The results show that most of alcoholic hydroxyl groups (85%) and a small part of phenolic hydroxyl groups (31%) in the lignin are subjected to esterification reaction with maleic anhydride under the condition of high-energy ball milling. Meanwhile, the hydroxyl value of the carboxyl hydroxyl is increased from 0.37mmol/g of the unmodified lignin to 1.37-1.60 mmol/g. Similar to the maleic anhydride modified lignin, the alcohol hydroxyl value of the succinic anhydride modified lignin-based polycarboxylic acid is reduced from unmodified 2.35mmol/g to modified 0.73-0.4mmol/g, the reduction is obvious, the phenol hydroxyl value is reduced slowly, and the unmodified 3.03mmol/g is reduced to only 2.81-2.28mmol/g, which shows that the succinic anhydride and most of alcohol hydroxyl groups (76%) and a very small part of phenol hydroxyl groups (16%) in the lignin are subjected to esterification reaction under the high-energy ball milling condition to generate the lignin-based polycarboxylic acid. The carboxyl hydroxyl value of the modified esterified lignin is increased from unmodified 0.37mmol/g to 1.11-1.48mmol/g, which indicates that the ring opening of the succinic anhydride is successfully carried out and the esterification reaction is carried out on the lignin to generate the lignin-based polycarboxylic acid. The lignin-derived polycarboxylic acid (LPCA) obtained by the reaction can be used as an epoxy curing agent and bisphenol A epoxy resin to generate a biomass-based thermosetting resin material through curing and crosslinking, the mechanical strength of the biomass-based thermosetting resin material is similar to that of a common resin material, and materials such as butadiene acrylonitrile rubber and the like can be added in the preparation process to toughen and modify the novel biomass-based composite resin material, so that the biomass-based resin material with more excellent performance is obtained.
TABLE 2 Effect of different stoichiometric ratios on the hydroxyl number of Lignin-based polycarboxylic acids
Finally, it is noted that the above-mentioned preferred embodiments illustrate rather than limit the invention, and that, although the invention has been described in detail with reference to the above-mentioned preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims.
Claims (7)
1. A method for preparing lignin-based polycarboxylic acid is characterized by comprising the following steps:
s10, mixing the lignin powder and the cyclic anhydride powder in a molar ratio of 1:1.0, 1:1.2, 1:1.4, 1:1.6, 1:1.8 and 1: 2.0;
s20, pouring the 6 groups of mixtures into 4 100mL zirconia ball milling tanks of a planetary ball mill respectively, and carrying out mechanochemical modification in groups;
s30, adding potassium hydroxide which accounts for 3-5 wt% of the total weight of the mixture into each zirconia ball milling tank to serve as an alkaline catalyst;
s40, the operation mode of the planetary ball mill is bidirectional, the frequency is 50Hz, and the rotation direction is changed once every 15 minutes;
s50, ball-milling for 100-140 minutes, and pouring out the cyclic anhydride modified lignin-based polycarboxylic acid from the planetary ball mill;
and S60, removing residual acid and a basic catalyst and drying.
2. The method of producing a lignin-based polycarboxylic acid according to claim 1, wherein said cyclic anhydride is succinic anhydride.
3. The method of claim 1, wherein the cyclic anhydride is maleic anhydride.
4. The method for preparing lignin-based polycarboxylic acid according to claim 1, wherein 16 zirconia balls with a diameter of 10mm and 100 zirconia balls with a diameter of 6mm are arranged in each zirconia ball milling pot as ball milling media.
5. The method of producing a lignin-based polycarboxylic acid according to claim 1, wherein said lignin is an organic solvent type.
6. The method for preparing lignin-based polycarboxylic acid according to claim 1, wherein said S60 is dried after removing residual acid and alkaline catalyst, comprising the steps of:
s61, removing residual cyclic anhydride by using distilled water, and rinsing for 2 times;
s62, neutralizing the mixed solution by using a dilute hydrochloric acid solution with the concentration of 0.5M, and removing the alkaline catalyst;
s63, rinsing the mixture for 2 times by using distilled water, and taking out a filter cake after filtering;
s64, drying in vacuum at 60-80 ℃ for 12 hours.
7. The lignin-based polycarboxylic acid produced by the production method according to any one of claims 1 to 6, wherein lignin and the cyclic acid anhydride are mixed in a molar ratio of 1:1.0, 1:1.2, 1:1.4, 1:1.6, 1:1.8 or 1:2.0, and the lignin and the cyclic acid anhydride are subjected to esterification reaction to obtain the lignin-based polycarboxylic acid.
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| WO2022267319A1 (en) * | 2021-06-24 | 2022-12-29 | 东北林业大学 | Method for improving dimensional stability of fast-growing wood by using lignin-based modified liquor |
| CN115926192A (en) * | 2023-01-06 | 2023-04-07 | 江南大学 | Bio-based powder coating and preparation method thereof |
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2020
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| XIAOJIE GUO，等: ""Preparation and toughening of mechanochemically modified lignin-based epoxy"", 《POLYMER》 * |
| 黄礼煌著: "《浮选》", 31 March 2018, 冶金工业出版社 * |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2022267319A1 (en) * | 2021-06-24 | 2022-12-29 | 东北林业大学 | Method for improving dimensional stability of fast-growing wood by using lignin-based modified liquor |
| CN115926192A (en) * | 2023-01-06 | 2023-04-07 | 江南大学 | Bio-based powder coating and preparation method thereof |
| CN115926192B (en) * | 2023-01-06 | 2023-07-07 | 江南大学 | Bio-based powder coating and preparation method thereof |
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