CN111393682B - Dynamic covalent cross-linked cellulose-based bioplastic, wood-plastic composite material, and preparation method and application thereof - Google Patents
Dynamic covalent cross-linked cellulose-based bioplastic, wood-plastic composite material, and preparation method and application thereof Download PDFInfo
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Abstract
The invention belongs to the field of material chemistry, and particularly discloses a dynamic covalent cross-linked cellulose-based bioplastic, a wood-plastic composite and a preparation method thereof. The method reconstructs a hydrogen bond bonding network among cellulose molecular chains into a dynamic covalent bond linking network, thereby preparing the cellulose-based bio-based plastic which can be thermally processed, has high strength and modulus, is degradable and can be recycled. Compared with most of the existing hydrogen bond linked cellulose-based materials, the preparation of the cellulose-based bioplastic provided by the invention is formed by crosslinking through dynamic covalent bonds, so that the cellulose-based bioplastic has excellent reprocessing, thermal processing and degradability. The novel wood-plastic composite material prepared from the composite material and biomass can improve the interface compatibility through the interaction of hydrogen bonds between the two phases, so that the novel wood-plastic composite material has higher tensile strength and Young modulus.
Description
Technical Field
The invention belongs to the field of material chemistry, and particularly relates to a dynamic covalent cross-linked cellulose-based bioplastic, a wood-plastic composite material, and a preparation method and application thereof.
Background
Plastics are an indispensable synthetic polymer material in human life. However, due to the non-degradability of plastics and the high recycling costs, only about 9% of plastics can be recycled at present. These waste plastics are buried in land in large quantities or discharged into the ocean, and have posed serious threats to the ecosystem. Meanwhile, the synthetic raw materials of the traditional plastics are all derived from non-renewable fossil resources. Therefore, research and development of biomass-based thermosetting/thermoplastic polymers that can replace traditional plastics is an urgent task.
At present, part of biomass-based plastics are developed and applied to the fields of biomedicine, packaging, agriculture and the like. The most common biomass based thermoplastic polymers are mixtures of thermoplastic starch (TPS) and aliphatic/aromatic polyesters such as polylactic acid (PLA), Polycaprolactone (PCL) and Polyhydroxyalkanoates (PHAs) and the like. However, the wide use of these bio-based plastics is still limited by their inherent disadvantages, such as poor processability, high brittleness, poor hydrophobicity, etc. In addition, some bio-based thermosetting polymers, such as biomass phenolic resin, biomass polyurethane, biomass epoxy resin, and the like, have been developed and applied, but compared with the traditional petroleum-based thermosetting polymers, the bio-based thermosetting polymers still have the disadvantages of low thermal stability, poor mechanical properties, insufficient chemical stability, and the like, so that the large-scale industrial production and application of the bio-based thermosetting polymers are still difficult to realize.
Cellulose is a biomass-based natural polymer with the largest reserve in nature. Compared with the traditional petroleum-based polymer, the cellulose not only has the reproducibility, but also can be completely biodegraded. Thus, cellulose is considered the best alternative to petroleum-based plastics. However, the very strong hydrogen bonding between cellulose chains makes them not only difficult to dissolve, but also impossible to thermoform like petroleum-based plastics. Although some researchers have modified cellulose through transesterification reaction to realize thermal processing of cellulose, such reaction can be carried out under high consumption conditions of catalysis, high temperature and the like, and the realization of industrialization is difficult. There is therefore a need to develop new, low-cost and more compact methods for preparing thermally processable cellulose-based polymers. The wood-plastic composite material integrates excellent performances of wood biomass and plastics, and is widely applied to industries such as outdoor building, indoor decoration, furniture, logistics packaging and the like. However, the raw materials of plastics such as Polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) and the like used in the preparation of the conventional wood-plastic composite are non-renewable, and the plastics cannot be chemically and biologically degraded, so that the conventional wood-plastic composite cannot have important characteristics such as sustainability and degradability. Meanwhile, the synthetic process of the biomass-based plastics such as polylactic acid and PBS is complex and high in cost, and is not suitable for being used as a raw material for producing the wood-plastic composite material.
Disclosure of Invention
The invention aims to provide a preparation method of dynamic covalent crosslinking cellulose-based bio-based plastics, which reconstructs a hydrogen bonding network among cellulose molecular chains into a dynamic covalent bonding link network, thereby preparing the cellulose-based bio-based plastics which can be thermally processed, has high strength and modulus, is degradable and can be recycled. The cellulose-based bioplastic provided by the invention has the advantages of simple production process, low production cost and easiness in large-scale production.
It is another object of the present invention to provide a dynamically covalently cross-linked cellulose-based bioplastic prepared by the above method.
The invention further aims to provide application of the dynamic covalent crosslinking cellulose-based bioplastic in the fields of packaging, circuit boards of electronic products, interior decoration, toy manufacturing and the like.
It is still another object of the present invention to provide a method for degradation and recovery of the above dynamic covalent cross-linked cellulose-based bioplastic.
The invention further aims to provide a wood-plastic composite material prepared from the dynamic covalent cross-linked cellulose-based bioplastic.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a method for preparing a dynamically covalently cross-linked cellulose-based bioplastic, comprising the steps of:
oxidizing cellulose by using periodate to prepare dialdehyde cellulose; dissolving dialdehyde cellulose to obtain dialdehyde cellulose solution; then reacting with a polyamine-based monomer to obtain a dynamic covalent (imine bond) crosslinked gel; washing and drying the obtained gel to obtain cellulose-based dynamic covalent polymer powder; and then performing a thermal shaping treatment on the cellulose-based dynamic covalent polymer powder to prepare the dynamic covalent crosslinked cellulose-based bioplastic.
Preferably, the cellulose raw material comprises any form of cellulose resources such as cellulose fibers, microcrystalline cellulose, nanocellulose, pulp board, dissolving pulp and the like. The cellulose is derived from any kind of plant, preferably at least one of softwood, hardwood, gramineae, grasses, bamboo, cotton and hemp. The periodate is preferably at least one of sodium periodate, potassium periodate, and barium periodate.
Preferably, the mass ratio of the periodate to the cellulose is 1: 2-2: 1;
preferably, the temperature of the periodate oxidized cellulose is 30-70 ℃, and the time is 5-40 h; more preferably, the temperature is 50 ℃ and the time is 10 h.
Preferably, the solvent for dissolving the dialdehyde cellulose is one of an organic solvent and an ionic solvent (ionic liquid); the organic solvent is DMSO, DMF or N-methylmorpholine.
Preferably, the mass volume ratio of the dialdehyde cellulose to the solvent is 1g to 30 ml-1 g to 10 ml;
preferably, the temperature for dissolving the dialdehyde cellulose by using the solvent is 50-110 ℃, and the time is 0.5-4 h.
Preferably, the multi-amino monomer includes any kind of multi-amino compound/oligomer/or polymer such as aliphatic diamine, aromatic diamine, aliphatic triamine, aromatic triamine, bio-based diamine/triamine, biomass-based diamine/triamine, etc.; preferred are butanediamine, pentanediamine, hexanediamine, octanediamine, decanediamine, and vegetable oleyldiamine.
Preferably, the amount of the dialdehyde cellulose and the polyamine group monomer is 1: 3-3: 1 of the molar ratio of aldehyde group to amino group.
Preferably, the reaction condition of the dialdehyde cellulose and the polyamine-based monomer is 1-24 h at room temperature.
Preferably, the thermoplastic forming method for obtaining the cellulose-based bio-plastic from the cellulose-based dynamic covalent polymer powder is a forming method such as flat plate hot pressing, extrusion forming, injection molding or 3D printing.
More preferably, the temperature of the flat plate hot pressing is 50-120 ℃, the pressure is 1.0-20 MPa, and the time is 1-40 min.
A cellulose-based bioplastic with dynamic covalent crosslinking, which is prepared by the method.
The cellulose-based bioplastic with dynamic covalent crosslinking can be widely applied to the fields of packaging, electronic product circuit boards, interior decoration, toy manufacturing and the like.
The invention further provides a method for degrading and recovering the dynamic covalent crosslinking cellulose-based bioplastic, which comprises the following steps:
firstly, soaking cellulose-based bioplastic to be degraded in a solution of an amine compound, an acidic solution or an alkaline solution to completely degrade the cellulose-based bioplastic; then separating the degraded dialdehyde cellulose and reaction monomers by a precipitation, filtration or centrifugation method, and then re-polymerizing the recovered dialdehyde cellulose and reaction monomers to prepare the recovered cellulose-based bioplastic.
The invention further provides a method for preparing the wood-plastic composite material by the dynamic covalent cross-linked cellulose-based bioplastic, which comprises the following specific steps:
mixing cellulose-based dynamic covalent polymer powder and natural biomass powder; soaking cellulose-based dynamic imine polymer/biomass mixed powder in water, and then carrying out vacuum filtration to remove redundant moisture; and carrying out thermoplastic treatment on the mixed powder to obtain the wood-plastic composite material.
Preferably, the natural biomass material can be chips, powder, filaments, fibers or microfine fibers; the natural biomass material is derived from plants or agricultural and forestry wastes. More preferably, the plant is coniferous wood, broadleaf wood, gramineous plants, grasses, bamboo, cotton or hemp; the agricultural and forestry wastes are branches, trunks, tree roots, sawdust, wood leftover materials, bamboo chips, bagasse, crop straws or fruit shells.
Preferably, the mass fraction of the biomass in the cellulose-based dynamic imine polymer/natural biomass mixed powder is 30-70%.
Preferably, the impregnation time of the cellulose-based dynamic imine polymer/natural biomass mixed powder in water is more than 30 min.
Preferably, the thermoplastic treatment is the same as the above-described method for cellulose-based dynamic covalent polymer powder.
Compared with the prior art, the invention has the following advantages and beneficial effects:
the invention directly takes cellulose biomass resources with wide sources as raw materials, and the cellulose-based bioplastic with dynamic covalent crosslinking can be obtained by simple periodate oxidation and then polymerization with diamine monomer at normal temperature. Compared with most of the existing hydrogen bond linked cellulose-based materials, the preparation of the cellulose-based bioplastic provided by the invention is formed by crosslinking through dynamic covalent bonds, so that the cellulose-based bioplastic has excellent reprocessing, thermal processing and degradability. In addition, the bioplastic prepared by the method has higher tensile strength and Young modulus, and the chemical reactions involved in the method do not need to use catalysts, can be carried out at room temperature, and is easy for industrial production. Therefore, the cellulose-based bioplastic prepared by the method has the advantages of high strength, high modulus, simple production process, low cost, environmental friendliness and the like. The novel wood-plastic composite material prepared from the composite material and biomass can improve the interface compatibility through the interaction of hydrogen bonds between the two phases, so that the novel wood-plastic composite material has higher tensile strength and Young modulus.
Drawings
FIG. 1 is a diagram of a synthetic reaction of a dynamically covalently (imine) crosslinked cellulose-based bioplastic;
FIG. 2 is a flow diagram of the preparation of a cellulose-based bioplastic that is dynamically covalently (iminium) crosslinked;
FIG. 3 is an infrared spectrum of cellulose-based bio-plastics 1 to 6 synthesized in examples 1 to 6; wherein, the dialdehyde cellulose-10 h is the curve of the dialdehyde cellulose obtained by the reaction for 10h in the embodiment 1-6.
FIG. 4 is a DSC chart of the cellulose-based bioplastics 1-5 synthesized in examples 1-5;
FIG. 5 is a Dynamic Mechanical Analysis (DMA) plot of the cellulose-based bioplastic 6 synthesized in example 6;
FIG. 6 is a graph comparing the tensile properties of cellulose-based bioplastics 1-6 synthesized in examples 1-6; wherein (a) is example 1-5, and (b) is example 6;
FIG. 7 is a tensile curve of cellulose-based bioplastic synthesized from dialdehyde cellulose-5 h in example 7;
FIG. 8 is a tensile curve of cellulose-based bioplastic synthesized from dialdehyde cellulose-40 h in example 8;
FIG. 9 is a tensile curve of the cellulose-based bioplastic synthesized in example 9 with a reaction time of 1 h;
FIG. 10 is a tensile curve of the cellulose-based bio-plastic synthesized under the condition of a reaction time of 24 hours in example 10;
FIG. 11 is a tensile curve at 50 ℃ for the cellulose-based bioplastic prepared in example 11 at a hot pressing temperature of 50 ℃;
FIG. 12 is a tensile curve of the cellulose-based bioplastic prepared at a hot pressing temperature of 120 ℃ in example 12-120 ℃;
FIG. 13 is a tensile curve of-1.0 MPa for the cellulose-based bioplastic prepared in example 13 at a hot pressing pressure of 1.0 MPa;
FIG. 14 is a tensile curve of 40MPa for a cellulose-based bioplastic prepared in example 14 at a hot pressing pressure of 40 MPa;
FIG. 15 is a tensile curve of the cellulose-based bioplastic prepared at a hot pressing time of 1min in example 15 for-1 min.
FIG. 16 is a tensile curve of the cellulose-based bioplastic prepared at 40min of hot pressing time in example 16, at-40 min.
FIG. 17 is a graph showing the degradation process of cellulose-based bio-plastic in example 17.
FIG. 18 is a graph comparing the tensile curves of the recycled cellulose-based plastic and the virgin cellulose-based plastic of example 17.
FIG. 19 is a schematic view of the preparation of the novel wood-plastic composite;
fig. 20 is a Scanning Electron Microscope (SEM) image of the novel wood-plastic composite prepared in examples 18 to 22;
FIG. 21 is a graph comparing tensile curves and Young's moduli of the novel wood-plastic composites prepared in examples 18 to 22;
FIG. 22 is a comparison graph of tensile curves of-50 ℃ and-120 ℃ for the novel wood-plastic composite prepared at the hot pressing temperatures of 50 ℃ and 120 ℃ in examples 23 and 24;
FIG. 23 is a graph comparing tensile curves of 1.0MPa for the novel wood-plastic composite and 40MPa for the novel wood-plastic composite prepared in examples 25 and 26 at hot pressing pressures of 1.0MPa and 40 MPa;
FIG. 24 is a graph comparing the tensile curves of the novel wood-plastic composite-3 min and the novel wood-plastic composite-50 min prepared at the hot pressing time of 3min and 50min in example 27 and example 28;
Detailed Description
The present invention will be described in further detail with reference to specific examples and drawings, but the embodiments of the present invention are not limited thereto, and process parameters not specifically noted may be performed with reference to conventional techniques.
The crumb or powder described in the present invention is obtained by the following process: the method comprises the steps of classifying and drying original biomass resources, then crushing and classifying the biomass resources to obtain fragments/powder with different sizes and specifications, and finally further drying the obtained biomass fragments.
Example 1
This example provides a method for preparing cellulose-based bioplastic 1 by polymerizing dialdehyde cellulose and butanediamine.
The preparation method of the cellulose-based bioplastic 1 comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 10 hours to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in fig. 1 and fig. 2, 0.5g of dialdehyde cellulose is dissolved in 8ml of DMSO for 1.5h, butanediamine is added according to the molar ratio of aldehyde group to amine group of 1:1, and the mixture is reacted for 8h at room temperature to obtain 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparing cellulose-based bioplastic: and carrying out hot pressing on the cellulose-based dynamic covalent polymer powder for 8min at 80 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic 1. FIG. 3 is an infrared spectrum showing the characteristic peak of aldehyde group (1730 cm) in the cellulose-based bioplastic 1-1) Completely disappear, and obvious imine bond characteristics appearPeak (1670 cm)-1) The successful synthesis of a dynamically covalently cross-linked cellulose-based bioplastic 1 was demonstrated. FIG. 4 is a DSC curve showing the dynamic covalent bond exchange temperature (T) of cellulose-based bioplastic 1v) And glass transition temperature (T)g) Respectively 80 ℃ and 140 ℃. The tensile curve of fig. 6 shows that the cellulose-based bioplastic 1 has a tensile strength of 16MPa, a tensile strain of 0.47%, and a young's modulus of 4.3 GPa.
Example 2
This example provides a method for preparing cellulose-based bioplastic 2 by polymerizing dialdehyde cellulose and pentanediamine.
The preparation method of the cellulose-based bioplastic 2 comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 10 hours to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in figure 1 and figure 2, 0.5g dialdehyde cellulose is dissolved in 8ml DMSO for 1.5h, pentanediamine is added according to the molar ratio of 1:1 of aldehyde group and amine group, and the reaction is carried out for 8h at room temperature, thus obtaining 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparing cellulose-based bioplastic: and carrying out hot pressing on the cellulose-based dynamic covalent polymer powder for 8min at 80 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic 2. FIG. 3 is an infrared spectrum showing the characteristic peak of aldehyde groups (1730 cm) in the cellulose-based bioplastic 2-1) Completely disappeared and a clear characteristic peak of imine bonds (1670 cm)-1) The successful synthesis of dynamically covalently cross-linked cellulose-based bioplastic 2 was demonstrated. FIG. 4 is a DSC curve showing the dynamic covalent bond exchange temperature (T) of cellulose-based bioplastic 2v) And glass transition temperature (T)g) Respectively at 80 ℃ and 135 ℃. The tensile curve of FIG. 6 shows that the cellulose-based bioplastic 2 has a tensile strength of 31MPa, a tensile strain of 1.31%, and Young's modulusThe modulus was 3.03 GPa.
Example 3
This example provides a method for preparing cellulose-based bioplastic 3 by polymerizing dialdehyde cellulose and hexamethylenediamine.
The preparation method of the cellulose-based bioplastic 3 comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 10 hours to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in figure 1 and figure 2, 0.5g dialdehyde cellulose is dissolved in 8ml DMSO for 1.5h, hexamethylenediamine is added according to the molar ratio of 1:1 of aldehyde group to amine group, and the reaction is carried out for 8h at room temperature, thus obtaining 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparing cellulose-based bioplastic: and carrying out hot pressing on the cellulose-based dynamic covalent polymer powder for 8min at 80 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic 3. FIG. 3 is an infrared spectrum showing the characteristic peak of aldehyde group (1730 cm) in cellulose-based bioplastic 3-1) Completely disappeared and a clear characteristic peak of imine bonds (1670 cm)-1) The successful synthesis of dynamically covalently cross-linked cellulose-based bioplastic 3 was demonstrated. FIG. 4 is a DSC curve showing the dynamic covalent bond exchange temperature (T) of cellulose-based bioplastic 3v) And glass transition temperature (T)g) 76 ℃ and 133 ℃ respectively. The tensile curve of fig. 6 shows that the cellulose-based bioplastic 3 has a tensile strength of 46MPa, a tensile strain of 2.2%, and a young's modulus of 2.87 GPa.
Example 4
This example provides a method for preparing cellulose-based bioplastic 4 by polymerizing dialdehyde cellulose and octanediamine.
The preparation method of the cellulose-based bioplastic 4 comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 10 hours to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in figure 1 and figure 2, 0.5g dialdehyde cellulose is dissolved in 8ml DMSO for 1.5h, octanediamine is added according to the molar ratio of aldehyde group to amine group of 1:1, and the reaction is carried out for 8h at room temperature, thus obtaining 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparing cellulose-based bioplastic: and carrying out hot pressing on the cellulose-based dynamic covalent polymer powder for 8min at 80 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic 4. FIG. 3 shows an IR spectrum showing a characteristic peak (1730 cm) for aldehyde groups in cellulose-based bioplastic 4-1) Completely disappeared and a clear characteristic peak of imine bonds (1670 cm)-1) The successful synthesis of dynamically covalently cross-linked cellulose-based bioplastic 4 was demonstrated. FIG. 4 is a DSC curve showing the dynamic covalent bond exchange temperature (T) of cellulose-based bioplastic 4v) And glass transition temperature (T)g) 73 ℃ and 140 ℃ respectively. The tensile curve of fig. 6 shows that the cellulose-based bioplastic 4 has a tensile strength of 40MPa, a tensile strain of 3.3%, and a young's modulus of 1.46 GPa.
Example 5
This example provides a method for preparing cellulose-based bioplastic 5 by polymerizing dialdehyde cellulose and decamethylene diamine.
The preparation method of the cellulose-based bioplastic 5 comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 10 hours to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in fig. 1 and fig. 2, 0.5g of dialdehyde cellulose is dissolved in 8ml of DMSO for 1.5h, decamethylene diamine is added according to the molar ratio of 1:1 of aldehyde group to amine group, and the mixture is reacted for 8h at room temperature to obtain 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparing cellulose-based bioplastic: and carrying out hot pressing on the cellulose-based dynamic covalent polymer powder for 8min at 80 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic 5. FIG. 3 shows an IR spectrum showing characteristic peak of aldehyde group (1730 cm) in cellulose-based bioplastic 5-1) Completely disappeared and a clear characteristic peak of imine bonds (1670 cm)-1) The successful synthesis of dynamically covalently cross-linked cellulose-based bioplastic 5 was demonstrated. FIG. 4 is a DSC curve showing the dynamic covalent bond exchange temperature (T) of cellulose-based bioplastic 5v) And glass transition temperature (T)g) 72 ℃ and 146 ℃ respectively. The tensile curve of fig. 6 shows that the cellulose-based bioplastic 5 has a tensile strength of 29MPa, a tensile strain of 3.3%, and a young's modulus of 1.03 GPa.
Example 6
This example provides a method for preparing cellulose-based bioplastic 6 by polymerizing dialdehyde cellulose and vegetable oil-based diamine (primamine).
The preparation method of the cellulose-based bioplastic 6 comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 10 hours to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in fig. 1 and fig. 2, 0.5g dialdehyde cellulose is dissolved in 8ml DMSO for 1.5h, vegetable oil-based diamine (primamine) is added according to the molar ratio of 1:1 of aldehyde group and amine group, and the mixture is reacted for 8h at room temperature to obtain 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparation of cellulose base raw materialPlastic: and carrying out hot pressing on the cellulose-based dynamic covalent polymer powder for 8min at 80 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic 6. FIG. 3 is an infrared spectrum showing the characteristic peak of aldehyde groups (1730 cm) in the cellulose-based bioplastic 6-1) Completely disappeared and a clear characteristic peak of imine bonds (1670 cm)-1) The successful synthesis of dynamically covalently cross-linked cellulose-based bioplastic 6 was demonstrated. The DMA curve of FIG. 5 shows the glass transition temperature (T) of the cellulose-based bioplastic 6g) The temperature was 130 ℃. The tensile curve of fig. 6 shows that the cellulose-based bioplastic 6 has a tensile strength of 22.5MPa, a tensile strain of 34%, and a young's modulus of 164 MPa.
Example 7
This example provides a method for preparing cellulose-based bioplastic using dialdehyde cellulose oxidized for 5h and hexamethylenediamine as raw materials.
The preparation method of the cellulose-based bioplastic comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 5 hours to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in figure 1 and figure 2, 0.5g dialdehyde cellulose is dissolved in 8ml DMSO for 1.5h, hexamethylenediamine is added according to the molar ratio of 1:1 of aldehyde group to amine group, and the reaction is carried out for 8h at room temperature, thus obtaining 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparing cellulose-based bioplastic: and carrying out hot pressing on the cellulose-based dynamic covalent polymer powder for 8min at 80 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic. The tensile curve of fig. 7 shows that the cellulose-based bioplastic has a tensile strength of 21MPa, a tensile strain of 1.1%, and a young's modulus of 3.38 GPa.
Example 8
This example provides a method for preparing cellulose-based bioplastic using dialdehyde cellulose oxidized for 40h and hexamethylenediamine as raw materials.
The preparation method of the cellulose-based bioplastic comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 40h to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in figure 1 and figure 2, 0.5g dialdehyde cellulose is dissolved in 8ml DMSO for 1.5h, hexamethylenediamine is added according to the molar ratio of 1:1 of aldehyde group to amine group, and the reaction is carried out for 8h at room temperature, thus obtaining 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparing cellulose-based bioplastic: and carrying out hot pressing on the cellulose-based dynamic covalent polymer powder for 8min at 80 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic. The tensile curve of fig. 8 shows that the cellulose-based bioplastic has a tensile strength of 36MPa, a tensile strain of 2.0%, and a young's modulus of 2.18 GPa.
Example 9
This example provides a method for preparing cellulose-based bioplastic with a reaction time of 1h between dialdehyde cellulose and hexamethylenediamine.
The preparation method of the cellulose-based bioplastic comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 10 hours to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in figure 1 and figure 2, 0.5g dialdehyde cellulose is dissolved in 8ml DMSO for 1.5h, hexamethylenediamine is added according to the molar ratio of 1:1 of aldehyde group to amine group, and the reaction is carried out for 1h at room temperature to obtain 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparing cellulose-based bioplastic: and carrying out hot pressing on the cellulose-based dynamic covalent polymer powder for 8min at 80 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic. The tensile curve of fig. 9 shows that the cellulose-based bioplastic has a tensile strength of 11.6MPa, a tensile strain of 0.5%, and a young's modulus of 2.32 GPa.
Example 10
This example provides a method for preparing cellulose-based bioplastic with a reaction time of 24h between dialdehyde cellulose and hexamethylenediamine.
The preparation method of the cellulose-based bioplastic comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 10 hours to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in figure 1 and figure 2, 0.5g dialdehyde cellulose is dissolved in 8ml DMSO for 1.5h, hexamethylenediamine is added according to the molar ratio of 1:1 of aldehyde group to amine group, and the reaction is carried out for 24h at room temperature, thus obtaining 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparing cellulose-based bioplastic: and carrying out hot pressing on the cellulose-based dynamic covalent polymer powder for 8min at 80 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic. The tensile curve of fig. 10 shows that the cellulose-based bioplastic has a tensile strength of 40MPa, a tensile strain of 1.7%, and a young's modulus of 2.35 GPa.
Example 11
This example provides a method for preparing cellulose-based bioplastic at 50 ℃ hot pressing temperature-50 ℃.
The preparation method of the cellulose-based bioplastic at the temperature of-50 ℃ comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 10 hours to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in figure 1 and figure 2, 0.5g dialdehyde cellulose is dissolved in 8ml DMSO for 1.5h, hexamethylenediamine is added according to the molar ratio of 1:1 of aldehyde group to amine group, and the reaction is carried out for 8h at room temperature, thus obtaining 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparing cellulose-based bioplastic: and hot-pressing the cellulose-based dynamic covalent polymer powder for 8min at 50 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic at-50 ℃. The tensile curve of fig. 11 shows that the cellulose-based bioplastic has a tensile strength of 24.9MPa, a tensile strain of 1.1%, and a young's modulus of 2.66 GPa.
Example 12
This example provides a process for preparing a cellulose-based bioplastic at-120 ℃ under hot pressing at a temperature of 120 ℃.
The preparation method of the cellulose-based bioplastic at-120 ℃ comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 10 hours to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in figure 1 and figure 2, 0.5g dialdehyde cellulose is dissolved in 8ml DMSO for 1.5h, hexamethylenediamine is added according to the molar ratio of 1:1 of aldehyde group to amine group, and the reaction is carried out for 8h at room temperature, thus obtaining 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparing cellulose-based bioplastic: and hot-pressing the cellulose-based dynamic covalent polymer powder for 8min at 120 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic at-120 ℃. The tensile curve of fig. 12 shows that the cellulose-based bioplastic has a tensile strength of 46MPa, a tensile strain of 2.1%, and a young's modulus of 2.64 GPa.
Example 13
This example provides a method for preparing a cellulose-based bioplastic at a hot pressing pressure of 1.0MPa to a pressure of 1.0 MPa.
The preparation method of the cellulose-based bioplastic with the pressure of-1.0 MPa comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 10 hours to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in figure 1 and figure 2, 0.5g dialdehyde cellulose is dissolved in 8ml DMSO for 1.5h, hexamethylenediamine is added according to the molar ratio of 1:1 of aldehyde group to amine group, and the reaction is carried out for 8h at room temperature, thus obtaining 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparing cellulose-based bioplastic: and carrying out hot pressing on the cellulose-based dynamic covalent polymer powder for 8min at 80 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic with the pressure of-1.0 MPa. The tensile curve of fig. 13 shows that the cellulose-based bioplastic has a tensile strength of 7.7MPa, a tensile strain of 0.2%, and a young's modulus of 4.36 GPa.
Example 14
This example provides a method for preparing a cellulose-based bioplastic at a hot pressing pressure of 40MPa to 40 MPa.
The preparation method of the cellulose-based bioplastic with the pressure of-40 MPa comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 10 hours to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in figure 1 and figure 2, 0.5g dialdehyde cellulose is dissolved in 8ml DMSO for 1.5h, hexamethylenediamine is added according to the molar ratio of 1:1 of aldehyde group to amine group, and the reaction is carried out for 8h at room temperature, thus obtaining 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparing cellulose-based bioplastic: and carrying out hot pressing on the cellulose-based dynamic covalent polymer powder for 8min at 80 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic with the pressure of-40 MPa. The tensile curve of fig. 14 shows that the cellulose-based bioplastic has a tensile strength of 46MPa, a tensile strain of 2.0%, and a young's modulus of 3.15 GPa.
Example 15
This example provides a method for preparing a cellulose-based bioplastic for-1 min at a hot pressing time of 1 min.
The preparation method of the cellulose-based bioplastic for 1min comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 10 hours to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in figure 1 and figure 2, 0.5g dialdehyde cellulose is dissolved in 8ml DMSO for 1.5h, hexamethylenediamine is added according to the molar ratio of 1:1 of aldehyde group to amine group, and reaction is carried out for 8h at room temperature to obtain 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparing cellulose-based bioplastic: and carrying out hot pressing on the cellulose-based dynamic covalent polymer powder for 1min at 80 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic for-1 min. The tensile curve of fig. 15 shows that the cellulose-based bioplastic has a tensile strength of 4.1MPa, a tensile strain of 0.12%, and a young's modulus of 3.79 GPa.
Example 16
This example provides a method for preparing cellulose-based bioplastic-40 min under hot pressing conditions of 40 min.
The preparation method of the cellulose-based bioplastic for-40 min comprises the following steps;
(1) preparing dialdehyde cellulose: dispersing 2g of microcrystalline cellulose in 250ml of water, adding 3.2g of sodium periodate, and reacting at 50 ℃ for 10 hours to obtain dialdehyde cellulose;
(2) synthesis of dynamic covalently cross-linked cellulose gel: as shown in figure 1 and figure 2, 0.5g dialdehyde cellulose is dissolved in 8ml DMSO for 1.5h, hexamethylenediamine is added according to the molar ratio of 1:1 of aldehyde group to amine group, and the reaction is carried out for 8h at room temperature, thus obtaining 100% dynamic covalent crosslinking cellulose gel;
(3) obtaining a cellulose-based dynamic covalent polymer powder: fully cleaning cellulose gel by using ethanol, and then drying the cellulose gel for 12 hours in vacuum at the temperature of 60 ℃ to obtain cellulose-based dynamic covalent polymer powder;
(4) preparing cellulose-based bioplastic: and carrying out hot pressing on the cellulose-based dynamic covalent polymer powder for 40min at 80 ℃ and 15MPa by using a flat hot press to obtain the cellulose-based bioplastic for-40 min. The tensile curve of fig. 16 shows that the cellulose-based bioplastic has a tensile strength of 46MPa, a tensile strain of 2.5%, and a young's modulus of 3.1 GPa.
Example 17
This example provides a method for the degradation and recovery of cellulose-based bioplastics.
The method comprises the following steps;
(1) as shown in fig. 17, the cellulose-based plastic 3 to be degraded is soaked in a DMSO solution of hexamethylenediamine (0.02M) and is magnetically stirred at 80 ℃ for 36 hours to completely degrade the cellulose-based plastic 3;
(2) precipitating by using ethanol, and recovering dialdehyde cellulose;
(3) evaporating the supernatant to dryness, and recovering hexamethylenediamine;
(4) the method of example 1 was followed to prepare a recycled cellulose-based bioplastic 3 using recycled dialdehyde cellulose and hexamethylenediamine as raw materials. The tensile curve of fig. 18 shows that the recycled cellulose-based bioplastic and the virgin cellulose-based plastic have the same mechanical properties.
Example 18
The embodiment provides a preparation method of a novel wood-plastic composite material containing 30% of biomass, namely 30%.
The preparation method of the novel wood-plastic composite material comprises the following steps;
(1) preparation of cellulose-based dynamic imine polymer powder: a powdered cellulose-based dynamic imine polymer 3 was prepared according to the method in example 3;
(2) preparing biomass powder: further crushing the collected poplar sawdust by using a crusher to obtain 80-mesh poplar powder, and drying the obtained poplar powder in an oven at 100 ℃ for 5 hours;
(3) preparation of biomass/cellulose-based dynamic imine polymer mixed powder: weighing 0.6g of poplar powder and 1.4g of cellulose-based dynamic imine polymer powder in an agate mortar according to the mass ratio of the poplar powder to the cellulose-based dynamic imine polymer of 3:7, and manually grinding for 5min to obtain uniformly mixed poplar powder/cellulose-based dynamic imine polymer powder mixed powder;
(4) preparation of biomass/cellulose-based dynamic imine polymer mixed powder containing moisture: dipping poplar powder/cellulose-based dynamic imine polymer mixed powder in deionized water for 40min, and then carrying out vacuum filtration to remove redundant moisture;
(5) preparing a novel wood-plastic composite material: placing the prepared poplar powder/cellulose-based dynamic imine polymer mixed powder containing moisture in a stainless steel mold, and then carrying out hot pressing in a flat hot press for 8min at the temperature of 80 ℃ and under the pressure of 15MPa to obtain the novel wood-plastic composite material containing 30% of biomass, wherein the mass of the composite material is 30%. The Scanning Electron Microscope (SEM) image of fig. 20 shows that in-30% of the novel wood-plastic composite, the biomass particles are completely encapsulated in the cellulose-based dynamic imine polymer matrix. The tensile data in fig. 21 shows that-30% tensile strength of the novel wood-plastic composite is 45.5MPa, young's modulus is 2.84GPa, and elongation at break is 2.2%.
Example 19
The embodiment provides a preparation method of a novel wood-plastic composite material containing 40% of biomass, namely 40%.
The preparation method of the novel wood-plastic composite material, namely 40 percent, comprises the following steps;
(1) preparation of cellulose-based dynamic imine polymer powder: a powdered cellulose-based dynamic imine polymer 3 was prepared according to the method in example 3;
(2) preparing biomass powder: further crushing the collected poplar sawdust by using a crusher to obtain 80-mesh poplar powder, and drying the obtained poplar powder in an oven at 100 ℃ for 5 hours;
(3) preparation of biomass/cellulose-based dynamic imine polymer mixed powder: weighing 0.8g of poplar powder and 1.2g of cellulose-based dynamic imine polymer powder in an agate mortar according to the mass ratio of the poplar powder to the cellulose-based dynamic imine polymer of 4:6, and manually grinding for 5min to obtain uniformly mixed poplar powder/cellulose-based dynamic imine polymer mixed powder;
(4) preparation of biomass/cellulose-based dynamic imine polymer mixed powder containing moisture: dipping poplar powder/cellulose-based dynamic imine polymer mixed powder in deionized water for 40min, and then carrying out vacuum filtration to remove redundant moisture;
(5) preparing a novel wood-plastic composite material: placing the prepared poplar powder/cellulose-based dynamic imine polymer mixed powder containing moisture in a stainless steel mold, and then carrying out hot pressing in a flat hot press for 8min at the temperature of 80 ℃ and under the pressure of 15MPa to obtain the novel wood-plastic composite material containing 40% of biomass-40%. The Scanning Electron Microscope (SEM) image of fig. 20 shows that in-40% of the novel wood-plastic composite, the biomass particles are completely encapsulated in the cellulose-based dynamic imine polymer matrix. The tensile data in fig. 21 shows that the tensile strength of the novel wood-plastic composite-40% is 46.9MPa, the young's modulus is 3.18GPa, and the elongation at break is 1.9%.
Example 20
This example provides a 50% preparation method of a novel wood-plastic composite containing 50% biomass.
The preparation method of the novel wood-plastic composite material, namely 50 percent, comprises the following steps;
(1) preparation of cellulose-based dynamic imine polymer powder: a powdered cellulose-based dynamic imine polymer 3 was prepared according to the method in example 3;
(2) preparing biomass powder: further crushing the collected poplar sawdust by using a crusher to obtain 80-mesh poplar powder, and drying the obtained poplar powder in an oven at 100 ℃ for 5 hours;
(3) preparation of biomass/cellulose-based dynamic imine polymer mixed powder: weighing 1.0g of poplar powder and 1.0g of cellulose-based dynamic imine polymer powder in an agate mortar according to the mass ratio of the poplar powder to the cellulose-based dynamic imine polymer of 5:5, and manually grinding for 5min to obtain uniformly mixed poplar powder/cellulose-based dynamic imine polymer mixed powder;
(4) preparation of biomass/cellulose-based dynamic imine polymer mixed powder containing moisture: soaking poplar powder/cellulose-based dynamic imine polymer powder mixed powder in deionized water for 40min, and then carrying out vacuum filtration to remove redundant moisture;
(5) preparing a novel wood-plastic composite material: placing the prepared poplar powder/cellulose-based dynamic imine polymer powder mixed powder containing moisture in a stainless steel mold, and then carrying out hot pressing in a flat hot press for 8min at 80 ℃ and 15MPa to obtain the novel wood-plastic composite material containing 50% of biomass, wherein the mass percent of the composite material is 50%. The Scanning Electron Microscope (SEM) image of fig. 20 shows that in-50% of the novel wood-plastic composite, part of the biomass particles are not completely encapsulated in the cellulose-based dynamic imine polymer matrix. The tensile data in fig. 21 shows that-50% tensile strength of the novel wood-plastic composite is 41.5MPa, young's modulus is 2.64GPa, and elongation at break is 1.9%.
Example 21
The embodiment provides a preparation method of 60% of novel wood-plastic composite material containing 60% of biomass.
The preparation method of the novel wood-plastic composite material comprises the following steps;
(1) preparation of cellulose-based dynamic imine polymer powder: a powdered cellulose-based dynamic imine polymer 3 was prepared according to the method in example 3;
(2) preparing biomass powder: further crushing the collected poplar sawdust by using a crusher to obtain 80-mesh poplar powder, and drying the obtained poplar powder in an oven at 100 ℃ for 5 hours;
(3) preparation of biomass/cellulose-based dynamic imine mixed powder: weighing 1.2g of poplar powder and 0.8g of cellulose-based dynamic imine polymer powder in an agate mortar according to the mass ratio of the poplar powder to the cellulose-based dynamic imine polymer of 6:4, and manually grinding for 5min to obtain uniformly mixed poplar powder/cellulose-based dynamic imine polymer powder mixed powder;
(4) preparation of biomass/cellulose-based dynamic imine polymer mixed powder containing moisture: soaking poplar powder/cellulose-based dynamic imine polymer powder mixed powder in deionized water for 40min, and then carrying out vacuum filtration to remove redundant moisture;
(5) preparing a novel wood-plastic composite material: placing the prepared poplar powder/cellulose-based dynamic imine polymer powder mixed powder containing moisture in a stainless steel mold, and then carrying out hot pressing in a flat hot press for 8min at 80 ℃ and 15MPa to obtain the novel wood-plastic composite material containing 60% of biomass, wherein the mass of the composite material is 60%. The Scanning Electron Microscope (SEM) image of fig. 20 shows that there are gaps of larger size in-60% of the novel wood-plastic composite. The tensile data in fig. 21 shows that the new wood-plastic composite-60% has a tensile strength of 35.3MPa, a young's modulus of 3.10GPa, and an elongation at break of 1.5%.
Example 22
The embodiment provides a preparation method of 70% of a novel wood-plastic composite material containing 70% of biomass.
The preparation method of the novel wood-plastic composite material comprises the following steps;
(1) preparation of cellulose-based dynamic imine polymer powder: a powdered cellulose-based dynamic imine polymer 3 was prepared according to the method in example 3;
(2) preparing biomass powder: further crushing the collected poplar sawdust by using a crusher to obtain 80-mesh poplar powder, and drying the obtained poplar powder in an oven at 100 ℃ for 5 hours;
(3) preparation of biomass/cellulose-based dynamic imine polymer mixed powder: weighing 1.4g of poplar powder and 0.6g of cellulose-based dynamic imine polymer powder in an agate mortar according to the mass ratio of the poplar powder to the cellulose-based dynamic imine polymer of 7:3, and manually grinding for 5min to obtain uniformly mixed poplar powder/cellulose-based dynamic imine polymer powder mixed powder;
(4) preparation of biomass/cellulose-based dynamic imine polymer mixed powder containing moisture: soaking poplar powder/cellulose-based dynamic imine polymer powder mixed powder in deionized water for 40min, and then carrying out vacuum filtration to remove redundant moisture;
(5) preparing a novel wood-plastic composite material: placing the prepared poplar powder/cellulose-based dynamic imine polymer powder mixed powder containing moisture in a stainless steel mold, and then carrying out hot pressing in a flat hot press for 8min at 80 ℃ and 15MPa to obtain the novel wood-plastic composite material containing 70% of biomass, wherein the mass of the composite material is 70%. The Scanning Electron Microscope (SEM) image of fig. 20 shows that there are many large-sized gaps in-70% of the new wood-plastic composite. The tensile data in fig. 21 shows that the new wood-plastic composite-70% has a tensile strength of 17.1MPa, a young's modulus of 2.18GPa, and an elongation at break of 1.0%.
Example 23
The embodiment provides a method for preparing a novel wood-plastic composite material at a temperature of 50 ℃ below zero under the condition that the hot pressing temperature is 50 ℃.
The preparation method of the novel wood-plastic composite material at the temperature of-50 ℃ comprises the following steps;
(1) preparation of cellulose-based dynamic imine polymer powder: a powdered cellulose-based dynamic imine polymer 3 was prepared according to the method in example 3;
(2) preparing biomass powder: further crushing the collected poplar sawdust by using a crusher to obtain 80-mesh poplar powder, and drying the obtained poplar powder in an oven at 100 ℃ for 5 hours;
(3) preparation of biomass/cellulose-based dynamic imine polymer mixed powder: weighing 0.6g of poplar powder and 1.4g of cellulose-based dynamic imine polymer powder in an agate mortar according to the mass ratio of the poplar powder to the cellulose-based dynamic imine polymer of 3:7, and manually grinding for 5min to obtain uniformly mixed poplar powder/cellulose-based dynamic imine polymer powder mixed powder;
(4) preparation of biomass/cellulose-based dynamic imine polymer mixed powder containing moisture: soaking poplar powder/cellulose-based dynamic imine polymer powder mixed powder in deionized water for 40min, and then carrying out vacuum filtration to remove redundant moisture;
(5) preparing a novel wood-plastic composite material: placing the prepared poplar powder/cellulose-based dynamic imine polymer powder mixed powder containing moisture in a stainless steel mold, and then carrying out hot pressing in a flat hot press for 8min at 50 ℃ and 15MPa to obtain the novel wood-plastic composite material containing 30% of biomass, wherein the temperature of the composite material is-50 ℃. The tensile curve of fig. 22 shows that the tensile strength of the novel wood-plastic composite material at-50 ℃ is 11.5MPa, the young's modulus is 2.63GPa, and the elongation at break is 0.44%.
Example 24
The embodiment provides a method for preparing a novel wood-plastic composite material at a temperature of 120 ℃ below zero.
The preparation method of the novel wood-plastic composite material at the temperature of-120 ℃ comprises the following steps;
(1) preparation of cellulose-based dynamic imine polymer powder: a powdered cellulose-based dynamic imine polymer 3 was prepared according to the method in example 3;
(2) preparing biomass powder: further crushing the collected poplar sawdust by using a crusher to obtain 80-mesh poplar powder, and drying the obtained poplar powder in an oven at 100 ℃ for 5 hours;
(3) preparation of biomass/cellulose-based dynamic imine polymer mixed powder: weighing 0.6g of poplar powder and 1.4g of cellulose-based dynamic imine polymer powder in an agate mortar according to the mass ratio of the poplar powder to the cellulose-based dynamic imine polymer of 3:7, and manually grinding for 5min to obtain uniformly mixed poplar powder/cellulose-based dynamic imine polymer powder mixed powder;
(4) preparation of biomass/cellulose-based dynamic imine polymer mixed powder containing moisture: soaking poplar powder/cellulose-based dynamic imine polymer powder mixed powder in deionized water for 40min, and then carrying out vacuum filtration to remove redundant moisture;
(5) preparing a novel wood-plastic composite material: placing the prepared poplar powder/cellulose-based dynamic imine polymer powder mixed powder containing moisture in a stainless steel mold, and then hot-pressing in a flat hot press for 8min at the temperature of 120 ℃ and under the pressure of 15MPa to obtain the novel wood-plastic composite material containing 30% of biomass, wherein the temperature is-120 ℃. The tensile curve of fig. 22 shows that the tensile strength of the novel wood-plastic composite material at-120 ℃ is 41.0MPa, the young's modulus is 2.93GPa, and the elongation at break is 2.1%.
Example 25
The embodiment provides a method for preparing a novel wood-plastic composite material under the condition that the hot-pressing pressure is 1MPa, wherein the pressure is 1 MPa.
The preparation method of the novel wood-plastic composite material with the pressure of-1 MPa comprises the following steps;
(1) preparation of cellulose-based dynamic imine polymer powder: a powdered cellulose-based dynamic imine polymer 3 was prepared according to the method in example 3;
(2) preparing biomass powder: further crushing the collected poplar sawdust by using a crusher to obtain 80-mesh poplar powder, and drying the obtained poplar powder in an oven at 100 ℃ for 5 hours;
(3) preparation of biomass/cellulose-based dynamic imine polymer mixed powder: weighing 0.6g of poplar powder and 1.4g of cellulose-based dynamic imine polymer powder in an agate mortar according to the mass ratio of the poplar powder to the cellulose-based dynamic imine polymer of 3:7, and manually grinding for 5min to obtain uniformly mixed poplar powder/cellulose-based dynamic imine polymer powder mixed powder;
(4) preparation of biomass/cellulose-based dynamic imine polymer mixed powder containing moisture: soaking poplar powder/cellulose-based dynamic imine polymer powder mixed powder in deionized water for 40min, and then carrying out vacuum filtration to remove redundant moisture;
(5) preparing a novel wood-plastic composite material: placing the prepared poplar powder/cellulose-based dynamic imine polymer powder mixed powder containing moisture in a stainless steel mold, and then carrying out hot pressing in a flat hot press for 8min at the temperature of 80 ℃ and under the pressure of 1MPa to obtain the novel wood-plastic composite material containing 30% of biomass, wherein the pressure of the novel wood-plastic composite material is-1 MPa. The tensile curve of fig. 23 shows that the tensile strength of the novel wood-plastic composite-1 MPa is 12.6MPa, the young's modulus is 2.94GPa, and the elongation at break is 0.43%.
Example 26
The embodiment provides a method for preparing a novel wood-plastic composite material under the condition that the hot-pressing pressure is 40MPa, wherein the pressure is 40 MPa.
The preparation method of the novel wood-plastic composite material with the pressure of-40 MPa comprises the following steps;
(1) preparation of cellulose-based dynamic imine polymer powder: a powdered cellulose-based dynamic imine polymer 3 was prepared according to the method in example 3;
(2) preparing biomass powder: further crushing the collected poplar sawdust by using a crusher to obtain 80-mesh poplar powder, and drying the obtained poplar powder in an oven at 100 ℃ for 5 hours;
(3) preparation of biomass/cellulose-based dynamic imine polymer mixed powder: weighing 0.6g of poplar powder and 1.4g of cellulose-based dynamic imine polymer powder in an agate mortar according to the mass ratio of the poplar powder to the cellulose-based dynamic imine polymer of 3:7, and manually grinding for 5min to obtain uniformly mixed poplar powder/cellulose-based dynamic imine polymer powder mixed powder;
(4) preparation of biomass/cellulose-based dynamic imine polymer mixed powder containing moisture: soaking poplar powder/cellulose-based dynamic imine polymer powder mixed powder in deionized water for 40min, and then carrying out vacuum filtration to remove redundant moisture;
(5) preparing a novel wood-plastic composite material: placing the prepared poplar powder/cellulose-based dynamic imine polymer powder mixed powder containing moisture in a stainless steel mold, and then carrying out hot pressing in a flat hot press for 8min at 80 ℃ and 40MPa to obtain the novel wood-plastic composite material containing 30% of biomass, wherein the pressure of the novel wood-plastic composite material is-1 MPa. The tensile curve of fig. 23 shows that the tensile strength of the novel wood-plastic composite-40 MPa is 43.1MPa, the young's modulus is 3.0GPa, and the elongation at break is 1.9%.
Example 27
The embodiment provides a method for preparing a novel wood-plastic composite material for-3 min under the condition that the hot pressing time is 3 min.
The preparation method of the novel wood-plastic composite material for-3 min comprises the following steps;
(1) preparation of cellulose-based dynamic imine polymer powder: a powdered cellulose-based dynamic imine polymer 3 was prepared according to the method in example 3;
(2) preparing biomass powder: further crushing the collected poplar sawdust by using a crusher to obtain 80-mesh poplar powder, and drying the obtained poplar powder in an oven at 100 ℃ for 5 hours;
(3) preparation of biomass/cellulose-based dynamic imine polymer mixed powder: weighing 0.6g of poplar powder and 1.4g of cellulose-based dynamic imine polymer powder in an agate mortar according to the mass ratio of the poplar powder to the cellulose-based dynamic imine polymer of 3:7, and manually grinding for 5min to obtain uniformly mixed poplar powder/cellulose-based dynamic imine polymer powder mixed powder;
(4) preparation of biomass/cellulose-based dynamic imine polymer mixed powder containing moisture: soaking poplar powder/cellulose-based dynamic imine polymer powder mixed powder in deionized water for 40min, and then carrying out vacuum filtration to remove redundant moisture;
(5) preparing a novel wood-plastic composite material: placing the prepared poplar powder/cellulose-based dynamic imine polymer powder mixed powder containing moisture in a stainless steel mold, and then carrying out hot pressing in a flat hot press for 3min at 80 ℃ and 15MPa to obtain the novel wood-plastic composite material containing 30% of biomass for-3 min. The tensile curve of fig. 24 shows that the tensile strength of the novel wood-plastic composite material at-3 min is 19.8MPa, the young's modulus is 2.87GPa, and the elongation at break is 0.69%.
Example 28
The embodiment provides a method for preparing a novel wood-plastic composite material for-50 min under the condition that the hot pressing time is 50 min.
The preparation method of the novel wood-plastic composite material for-50 min comprises the following steps;
(1) preparation of cellulose-based dynamic imine polymer powder: a powdered cellulose-based dynamic imine polymer 3 was prepared according to the method in example 3;
(2) preparing biomass powder: further crushing the collected poplar sawdust by using a crusher to obtain 80-mesh poplar powder, and drying the obtained poplar powder in an oven at 100 ℃ for 5 hours;
(3) preparation of biomass/cellulose-based dynamic imine polymer mixed powder: weighing 0.6g of poplar powder and 1.4g of cellulose-based dynamic imine polymer powder in an agate mortar according to the mass ratio of the poplar powder to the cellulose-based dynamic imine polymer of 3:7, and manually grinding for 5min to obtain uniformly mixed poplar powder/cellulose-based dynamic imine polymer powder mixed powder;
(4) preparation of biomass/cellulose-based dynamic imine polymer mixed powder containing moisture: soaking poplar powder/cellulose-based dynamic imine polymer powder mixed powder in deionized water for 40min, and then carrying out vacuum filtration to remove redundant moisture;
(5) preparing a novel wood-plastic composite material: placing the prepared poplar powder/cellulose-based dynamic imine polymer powder mixed powder containing moisture in a stainless steel mold, and then carrying out hot pressing in a flat hot press for 50min at 80 ℃ and 15MPa to obtain the novel wood-plastic composite material containing 30% of biomass for-50 min. The tensile curve of fig. 24 shows that the tensile strength of the novel wood-plastic composite material is 50.3MPa in-50 min, the young's modulus is 3.22GPa, and the elongation at break is 1.96%.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (9)
1. A method for preparing a cellulose-based bioplastic with dynamic covalent cross-linking, characterized by comprising the following steps:
oxidizing cellulose by using periodate to prepare dialdehyde cellulose; dissolving dialdehyde cellulose in DMSO to obtain dialdehyde cellulose solution; then reacting with a polyamine-based monomer at room temperature for 1-24 h to obtain dynamic covalent crosslinking gel; washing and drying the obtained gel to obtain cellulose-based dynamic covalent polymer powder; then carrying out flat plate hot pressing treatment on the cellulose-based dynamic covalent polymer powder to prepare dynamic covalent cross-linked cellulose-based bioplastic; the using amount of the dialdehyde cellulose and the polyamine-based monomer meets the condition that the molar ratio of aldehyde groups to amino groups is 1: 3-3: 1;
the polyamine monomer is aliphatic diamine, aromatic diamine, aliphatic triamine or aromatic triamine.
2. The method of claim 1, wherein: the mass ratio of the periodate to the cellulose is 1: 2-2: 1; the temperature of the periodate for oxidizing the cellulose is 30-70 ℃, and the time is 5-40 h.
3. The method of claim 1, wherein:
the mass-volume ratio of the dialdehyde cellulose to the DMSO is 1g:30 ml-1 g:10 ml;
the temperature for dissolving the dialdehyde cellulose by using the DMSO is 50-110 ℃, and the time is 0.5-4 h.
4. The method of claim 1, wherein:
the temperature of the flat plate hot pressing is 50-120 ℃, the pressure is 1.0-20 MPa, and the time is 1-40 min;
the cellulose raw material is cellulose fiber, microcrystalline cellulose, nano cellulose, pulp board or dissolving pulp.
5. A dynamically covalently cross-linked cellulose-based bioplastic prepared by the method of any one of claims 1 to 4.
6. Use of the dynamically covalently crosslinked cellulose-based bioplastic according to claim 5 for the production of packaging, circuit boards for electronic products, interior materials or toys.
7. A method for degradation and recovery of a dynamically covalently cross-linked cellulose-based bioplastic according to claim 5, characterized in that it is as follows:
firstly, soaking cellulose-based bioplastic to be degraded in a solution of amine compounds to completely degrade the cellulose-based bioplastic; then separating the degraded dialdehyde cellulose and reaction monomers by a precipitation, filtration or centrifugation method, and then re-polymerizing the recovered dialdehyde cellulose and reaction monomers to prepare the recovered cellulose-based bioplastic; the solution of the amine compound is a DMSO solution of hexamethylene diamine.
8. A method for preparing a wood-plastic composite from the dynamic covalent cross-linked cellulose-based bio-plastic according to claim 5, characterized by the following specific steps: mixing cellulose-based dynamic covalent polymer powder and natural biomass powder; then soaking the cellulose-based dynamic covalent polymer powder/natural biomass mixed powder in water, and then carrying out vacuum filtration to remove redundant moisture; performing thermoplastic treatment on the mixed powder to obtain a wood-plastic composite material;
the natural biomass is plants and agricultural and forestry wastes, and the plants are coniferous trees, broadleaf trees and gramineous plants; the agricultural and forestry wastes are branches, trunks, tree roots, sawdust, wood leftover materials, bamboo chips, bagasse, crop straws and fruit shells.
9. The method of claim 8, wherein: the mass fraction of biomass in the cellulose-based dynamic imine polymer/natural biomass mixed powder is 30-70%; the dipping time of the cellulose-based dynamic imine polymer/natural biomass mixed powder in water is more than 30 min.
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