Low-content high-performance CMC / PBST composite material as well as preparation method and application thereof

Abstract

The invention discloses a low-content high-performance CMC / PBST composite material as well as a preparation method and application thereof, the composite material comprises nano-crystalline cellulose (CMC), PBST, an antioxidant and a chain extender, and the nano-crystalline cellulose is obtained by sequentially crushing, dissolving and washing, acidifying, alkylating and drying plant fibers; based on the mass of PBST, the addition amount of the nanocellulose crystal is 0.5-5.0 wt%, the addition amount of the chain extender is 0-10 wt%, and the addition amount of the antioxidant is 0.5-2 wt%. The preparation method comprises the following steps: pre-treating the plant fibers; then, the pretreated plant fibers and the pretreated PBST granules are reacted, extruded and blended according to the proportion; under the condition of lower CNC content, the tensile strength and the elongation at break of the prepared composite material are respectively improved by 100-300% and 50-100% compared with those of pure PBST; the melt strength is also improved; the spinning process of the composite material is smooth, the performance of the obtained fiber basically meets the application requirements, and the composite material is expected to be applied to the field of fiber manufacturing.

Description

Technical Field

[0001] This invention relates to the field of biodegradable polymer materials technology, and in particular to a low-content, high-performance CMC / PBST composite material, its preparation method, and its applications. Background Technology

[0002] Polybutylene succinate-co-butylene terephthalate (PBST) is a novel biodegradable synthetic polymer material. However, PBST's temperature sensitivity during processing leads to significant temperature variations in its properties. Currently, PBST modification processes are not yet fully mature, research reports are limited, and reports on its spinning applications are even fewer. Cellulose nanofibril (CNF) possesses advantages such as high mechanical strength, high aspect ratio, and biodegradability, making it an excellent environmentally friendly nanomaterial. However, traditional CNFs, due to their abundant hydrophilic hydroxyl groups on the surface, are difficult to disperse uniformly in hydrophobic polymer matrices such as polyesters and are prone to agglomeration. This increases processing difficulty and significantly reduces the mechanical properties of the resulting composite materials.

[0003] Existing technologies for modifying polymer composites with nanocellulose mainly focus on the preparation and surface modification of nanocellulose to improve its dispersion in the matrix (e.g., Journal of Renewable Materials, 2019, Vol. 7, pp. 269-277; Journal of Applied Polymer Science, 2023, 140.42:e54543; In: AIP Conference Proceedings. AIP Publishing, 2020). These reports describe the preparation and modification of nanocellulose in detail. However, the entire process is time-consuming and uses highly toxic organic solvents, which greatly affects the environmental friendliness of nanocellulose.

[0004] In addition, Chinese patent CN102295827A discloses a method for preparing a polysaccharide composite polyester material. This method involves solution blending or melt blending cellulose or starch nanocrystals with polybutylene succinate to obtain a solid mixture, which is then hot-pressed to obtain the composite material. The addition amount is 1-15 wt%, but no specific spinning process or corresponding technical indicators are given. Chinese patent CN202211710129 discloses a method for preparing a biodegradable nanocellulose-reinforced composite material, detailing the surface treatment method for cellulose, wherein the cellulose powder content is 10-60 wt%, but no preparation process or specific performance indicators for the reinforced composite material are given. Chinese patent CN202110180299 discloses a biodegradable filament and its preparation method, using a flexible thermoplastic biodegradable polymer and cellulose powder as raw materials, and obtaining the biodegradable filament under a certain spinning process, wherein the cellulose powder content is 10-60 wt%, indicating a relatively high cellulose powder addition amount.

[0005] Therefore, the main problem with existing methods for preparing cellulose-reinforced composites is that direct blending via physical methods (organic solvents or mechanical blending) results in poor compatibility between cellulose and the polymer matrix, leading to limited or even worse performance improvement in the composites, and no significant improvement in degradation performance. Furthermore, current preparation techniques suffer from other issues, such as improper cellulose size causing difficulties or even preventing the spinning process of the composites. Moreover, in existing technologies, the addition amount of both cellulose powder and modified starch (CN202110882423) exceeds 10 wt%, and high powder content easily causes agglomeration in the polymer matrix, leading to performance degradation. Simultaneously, the long and costly cellulose preparation process hinders cost control and large-scale promotion of composites. Therefore, it is necessary to develop a method for preparing low-content biodegradable nanocellulose-reinforced composites that overcomes the above-mentioned defects, and to develop a suitable melt processing method to prepare nanocellulose crystal (CNC) composites with good mechanical properties. Then, based on this composite, biodegradable fibers can be produced under appropriate spinning conditions. Summary of the Invention

[0006] The purpose of this invention is to provide a low-content, high-performance CMC / PBST composite material, its preparation method, and its application, in order to solve the problems of poor compatibility between cellulose and polymer matrices and high cellulose addition.

[0007] To achieve the above objectives, the first aspect of the present invention provides a low-content, high-performance CMC / PBST composite material, comprising nanocellulose crystals, PBST, antioxidants, and chain extenders, wherein the nanocellulose crystals are obtained by sequentially crushing, washing, acidifying, alkylating, and drying plant fibers;

[0008] Based on the mass of PBST, the amount of nanocellulose crystals added is 0.5-5.0 wt%, the amount of chain extender added is 0-10 wt%, and the amount of antioxidant added is 0.5-2 wt%.

[0009] Preferably, the amount of chain extender added is 0.5-7 wt%, more preferably 1-4 wt%.

[0010] Preferably, the plant fiber is at least one of corn stalks, wheat straw, rice straw, coconut shell fiber, pine needles, and bamboo fiber.

[0011] The preferred method for preparing nano-cellulose crystals is as follows:

[0012] (1) The crushed, washed and separated plant fibers are added to a sulfuric acid solution for heating and hydrolysis. After hydrolysis, the fibers are cooled, centrifuged, washed and dried to obtain acid-hydrolyzed powder.

[0013] (2) Add glacial acetic acid to the mixture of ethanol and water, adjust the pH to 4-5, then add silane coupling agent, heat and stir until clear, and obtain a mixed solution;

[0014] (3) Add the acid-hydrolyzed powder to the mixed solution, heat and stir to complete the silane modification, cool to room temperature, filter, wash and dry to obtain nanocellulose crystals.

[0015] Preferably, in step (1), the concentration of sulfuric acid solution is 35-45%, the temperature of heating and hydrolysis is 40-50℃, the time is 0.5-1h, and the solid-liquid ratio of plant fiber to sulfuric acid solution is 1:(8-12).

[0016] Preferably, in step (2), the volume ratio of ethanol to water is (8-10):1, the silane coupling agent is at least one of KH550, KH560 or KH570, the ratio of the amount of silane coupling agent added to the cellulose crystals is (1-2):(1-5), the heating and stirring temperature is 55-65℃, and the stirring speed is 500-800r / min;

[0017] In step (3), the solid-liquid ratio of the acid-hydrolyzed powder and the mixed solution is 1:(2-10), the heating and stirring temperature is 110-130℃, and the time is 1-3h.

[0018] Preferably, the drying temperature in step (3) is 80-90℃ and the drying time is 6-12h.

[0019] Preferably, the molecular weight of PBST is between 10,000 and 100,000, and the polydispersity index is between 1.1 and 4.0.

[0020] Preferably, the molecular weight of PBST is between 20,000 and 100,000, and the polydispersity index is between 1.1 and 3.0.

[0021] Preferably, the antioxidants include antioxidant 168 and antioxidant 1010, and the mass ratio of antioxidant 168 to antioxidant 1010 is 1:1.

[0022] Preferably, the chain extender is at least one of toluene-2,4-diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane-4,4-diisocyanate, isoflurone diisocyanate, hexamethylene diisocyanate, and maleic anhydride.

[0023] A second aspect of this invention provides a method for preparing a low-content, high-performance CMC / PBST composite material, comprising the following steps:

[0024] S1: Vacuum dry PBST and antioxidant to remove moisture, and set aside;

[0025] S2: Thoroughly mix the dried PBST, antioxidant, and nanocellulose crystals, add them to a mixer, and melt the PBST completely at 140-170℃. Then add the chain extender to carry out an extrusion blending modification reaction. The speed of the mixer is 25-60 r / min, and the blending time is 2-10 min. After drying, the CNC / PBST composite material is obtained and ready for use.

[0026] S3: The CNC / PBST composite material is melt-spun to obtain biodegradable fibers.

[0027] Preferably, 0.01 wt% (based on the mass of PBST) of liquid paraffin can be added to the dried PBST in step S1 to ensure that the powder components are mixed with the PBST particles.

[0028] Preferably, the spinning process in step S3 is melt spinning, which is carried out using a small twin-screw spinning machine, including five heating zones: 125-135℃, 140-155℃, 155-175℃, 155-175℃, and 140-155℃. After heating, cooling and hot roller stretching and shaping are performed. The hot rollers are three-dimensional: the first hot roller temperature is 80-90℃, the second hot roller temperature is 100-120℃, and the third hot roller temperature is 20-30℃. The stretching ratios are 2.0-4.0 and 1.2-2.0, respectively, and the winding speed is 200-1000 m / min.

[0029] Preferably, the biodegradable fiber prepared in step S3 has a fiber strength of 1.2-2.5 cN / dtex and a breaking elongation of 30-200%.

[0030] The third aspect of this invention provides an application of a low-content, high-performance CMC / PBST composite material in the textile field.

[0031] Therefore, the low-content, high-performance CMC / PBST composite material with the above-described structure, its preparation method, and its application have the following beneficial effects:

[0032] (1) Compared with existing high-content cellulose-modified polyesters, this invention adopts the method of adding a third component (chain extender) and uses the reaction melt blending method to achieve the reinforcement modification of PBST by low-content nanocellulose crystals, improves the compatibility between nanocellulose crystals and PBST, and significantly reduces the amount of nanocellulose crystals used while ensuring the strength of the composite material, thus achieving the purpose of green environmental protection and cost reduction.

[0033] (2) This invention realizes the melt spinning of CNC / PBST composite material and optimizes the spinning process. The resulting fiber has good properties and broadens the application of PBST in the textile field.

[0034] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0035] Figure 1 This is the tensile curve of the CMC / PBST composite material. Detailed Implementation

[0036] The present invention will be further described below. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the present invention is not limited to this embodiment.

[0037] Example 1

[0038] A method for preparing a low-content, high-performance CMC / PBST composite material includes the following steps:

[0039] Step 1: The preparation method of nano-cellulose crystals is as follows:

[0040] (1) The plant fiber was crushed in a pulverizer and then washed multiple times with anhydrous ethanol. After washing, the fiber was separated and dried at 120°C to obtain plant fiber powder with a particle size of 3000 nm.

[0041] (2) The crushed, washed and separated plant fibers are added to a sulfuric acid solution for heating and hydrolysis. After hydrolysis, the fibers are cooled, centrifuged, washed and dried to obtain acid-hydrolyzed powder.

[0042] The concentration of the sulfuric acid solution was 40%, the temperature for hydrolysis was 45℃, the time was 0.5h, and the solid-liquid ratio of the plant fiber to the sulfuric acid solution was 1:10.

[0043] (3) Add glacial acetic acid to the mixture of ethanol and water to adjust the pH to 4, then add silane coupling agent, heat and stir until clear to obtain a mixed solution;

[0044] The volume ratio of ethanol to water is 9:1, the silane coupling agent is KH550, the ratio of the amount of silane coupling agent added to cellulose crystals is 2:1, the heating and stirring temperature is 60℃, and the stirring speed is 600r / min.

[0045] (4) Add the acid-hydrolyzed powder to the mixed solution, heat and stir to complete the silane modification, cool to room temperature, filter, wash and dry to obtain nanocellulose crystals;

[0046] The solid-liquid ratio of the acid-hydrolyzed powder and the mixed solution was 1:2. The heating and stirring temperature was 120℃ for 2 hours. The drying temperature was 85℃ for 8 hours.

[0047] Step 2: Dry PBST (PBST is polybutylene succinate-co-terephthalate with a molecular weight of 20,000 and a polydispersity index of 3.0 produced by BASF New Materials Co., Ltd. in Shanghai), antioxidant 168 and antioxidant 1010 (commercially available) at 80°C for 24 hours in a dynamic vacuum drying oven.

[0048] Step 3: Add 0.01 wt% liquid paraffin (based on the mass of PBST) to the dried PBST, stir at high speed, then add 0.5 wt% each of antioxidant 168 and antioxidant 1010 (based on the mass of PBST), mix thoroughly, pour into a Hacker rheometer, and after melting, the blending temperature is 140℃, the speed is 30 r / min, and the time is 5 min. After the sample is taken out and allowed to cool naturally, it is then bagged.

[0049] Step 4: Thoroughly mix the well-mixed PBST, antioxidant, and 0.5 wt% (based on the mass of PBST) nanocellulose crystals, add them to a mixer, and melt the PBST completely at 150°C. Then add 0.5 wt% (based on the mass of PBST) chain extender toluene-2,4-diisocyanate for extrusion blending modification reaction. The speed of the mixer is 40 r / min, and the blending time is 5 min. After drying, the CNC / PBST composite material is obtained for later use.

[0050] The prepared CNC / PBST composite material was dried at 90℃ for 6 hours in a dynamic vacuum oven, then pressed into sheets (1 mm thick) and cut into pieces on a flat vulcanizing machine. The mechanical properties were tested according to GB / T 1040.2-2006, and the test results are shown in Table 1.

[0051] Step 4: After thoroughly drying the CNC / PBST composite material, melt spinning is performed. The spinning equipment used is a small twin-screw spinning machine with 5 heating zones: 125℃, 140℃, 155℃, 155℃, and 140℃, respectively. Water bath cooling is followed by hot roller stretching and shaping: the first hot roller temperature is 80℃, the second is 100℃, and the third is 25℃; the draw ratios are 2.5 and 1.5 respectively; the winding speed is 300 m / min.

[0052] The prepared fiber has a strength of 1.6 cN / dtex and a breaking elongation of 300%.

[0053] Example 2

[0054] A method for preparing a low-content, high-performance CMC / PBST composite material includes the following steps:

[0055] Step 1: The preparation method of nano-cellulose crystals is as follows:

[0056] (1) The plant fiber was crushed in a pulverizer and then washed multiple times with anhydrous ethanol. After washing, the fiber was separated and dried at 120°C to obtain plant fiber powder with a particle size of 200 nm.

[0057] (2) The crushed, washed and separated plant fibers are added to a sulfuric acid solution for heating and hydrolysis. After hydrolysis, the fibers are cooled, centrifuged, washed and dried to obtain acid-hydrolyzed powder.

[0058] The concentration of the sulfuric acid solution was 40%, the temperature for hydrolysis was 45℃, the time was 0.5h, and the solid-liquid ratio of the plant fiber to the sulfuric acid solution was 1:10.

[0059] (3) Add glacial acetic acid to the mixture of ethanol and water to adjust the pH to 4.5, then add silane coupling agent, heat and stir until clear to obtain a mixed solution;

[0060] The volume ratio of ethanol to water is 9:1, the silane coupling agent is KH560, the ratio of the amount of silane coupling agent added to cellulose crystals is 1:1, the heating and stirring temperature is 60℃, and the stirring speed is 600r / min.

[0061] (4) Add the acid-hydrolyzed powder to the mixed solution, heat and stir to complete the silane modification, cool to room temperature, filter, wash and dry to obtain nanocellulose crystals;

[0062] The solid-liquid ratio of the acid-hydrolyzed powder and the mixed solution was 1:3. The heating and stirring temperature was 120℃ for 2 hours; the drying temperature was 80℃ for 10 hours.

[0063] Step 2: Dry PBST (PBST is polybutylene succinate-co-terephthalate with a molecular weight of 20,000 and a polydispersity index of 2.5 produced by BASF New Materials Co., Ltd. in Shanghai), antioxidant 168 and antioxidant 1010, which are commercially available, in a dynamic vacuum drying oven at 80°C for 24 hours.

[0064] Step 3: Add 0.01 wt% (based on the mass of PBST) of liquid paraffin to the dried PBST, stir at high speed, then add 0.5 wt% each of antioxidant 168 and 1010 (based on the mass of PBST), mix thoroughly, pour into a Hacker rheometer, mix at 145℃, rotate at 35 r / min, for 5 min, and then bag the sample after it has cooled naturally.

[0065] Step 4: Thoroughly mix the dried PBST, antioxidant, and 1 wt% (based on the mass of PBST) nanocellulose crystals, add them to a mixer, and melt the PBST completely at 160°C. Then add 1.0 wt% toluene-2,4-diisocyanate (TDI) (based on the mass of PBST) and carry out an extrusion blending modification reaction. The speed of the mixer is 50 r / min, and the blending time is 4 min. After drying, the CNC / PBST composite material is obtained and ready for use.

[0066] The prepared CNC / PBST composite material was dried at 90℃ for 6 hours in a dynamic vacuum oven, then pressed into sheets (1 mm thick) and cut into pieces on a flat vulcanizing machine. The mechanical properties were tested according to GB / T 1040.2-2006, and the test results are shown in Table 1.

[0067] Step 5: After thoroughly drying the CNC / PBST composite material, melt spinning was performed. The spinning equipment used was a small twin-screw spinning machine with 5 heating zones: 130℃, 145℃, 160℃, 160℃, and 142℃, respectively. Water bath cooling was followed by hot roller stretching and shaping: the first hot roller temperature was 85℃, the second hot roller temperature was 102℃, and the third hot roller temperature was 28℃; the draw ratios were 3.0 and 1.6, respectively; and the winding speed was 400 m / min.

[0068] The prepared fiber has a strength of 1.9 cN / dtex and a breaking elongation of 250%.

[0069] Example 3

[0070] A method for preparing a low-content, high-performance CMC / PBST composite material includes the following steps:

[0071] Step 1: The preparation method of nano-cellulose crystals is as follows:

[0072] (1) The plant fiber was crushed in a pulverizer and then washed multiple times with anhydrous ethanol. After washing, the fiber was separated and dried at 120°C to obtain plant fiber powder with a particle size of 500 nm.

[0073] (2) The crushed, washed and separated plant fibers are added to a sulfuric acid solution for heating and hydrolysis. After hydrolysis, the fibers are cooled, centrifuged, washed and dried to obtain acid-hydrolyzed powder.

[0074] The concentration of the sulfuric acid solution was 40%, the temperature for hydrolysis was 40℃, the time was 1 hour, and the solid-liquid ratio of the plant fiber to the sulfuric acid solution was 1:10.

[0075] (3) Add glacial acetic acid to the mixture of ethanol and water, adjust the pH to 5, then add silane coupling agent, heat and stir until clear, and obtain a mixed solution;

[0076] The volume ratio of ethanol to water is 9:1, the silane coupling agent is KH570, the ratio of the amount of silane coupling agent added to cellulose crystals is 1:2, the heating and stirring temperature is 65℃, and the stirring speed is 500r / min.

[0077] (4) Add the acid-hydrolyzed powder to the mixed solution, heat and stir to complete the silane modification, cool to room temperature, filter, wash and dry to obtain nanocellulose crystals;

[0078] The solid-liquid ratio of the acid-hydrolyzed powder and the mixed solution was 1:5. The heating and stirring temperature was 120℃ for 2 hours. The drying temperature was 90℃ for 6 hours.

[0079] Step 2: Dry PBST (PBST is polybutylene succinate-co-terephthalate with a molecular weight of 20,000 and a polydispersity index of 1.8 produced by BASF New Materials Co., Ltd. in Shanghai), antioxidant 168 and antioxidant 1010, which are commercially available, in a dynamic vacuum drying oven at 80°C for 24 hours.

[0080] Step 3: Add 0.01 wt% (based on the mass of PBST) of liquid paraffin to the dried PBST, stir at high speed, then add 0.5 wt% each of antioxidant 168 and 1010 (based on the mass of PBST), mix thoroughly, pour into a Hacker rheometer, mix at 150℃, speed of 45 r / min, time of 5 min, and then bag the sample after it has cooled naturally.

[0081] Step 4: Thoroughly mix the dried PBST, antioxidant, and 2.0 wt% nanocellulose crystals (based on the mass of PBST), add them to a mixer, and melt the PBST completely at 160°C. Then add 1.0 wt% toluene-2,4-diisocyanate (TDI) (based on the mass of PBST) for extrusion blending modification reaction. The speed of the mixer is 45 r / min, and the blending time is 8 min. After drying, the CNC / PBST composite material is obtained for later use.

[0082] The prepared CNC / PBST composite material was dried at 90℃ for 6 hours in a dynamic vacuum oven, then pressed into sheets (1 mm behind the sheet) and cut into pieces on a flat vulcanizing machine. The mechanical properties were tested according to GB / T 1040.2-2006. The test results are shown in Table 1.

[0083] Step 5: After thoroughly drying the CNC / PBST composite material, melt spinning was performed. The spinning equipment used was a small twin-screw spinning machine with 5 heating zones: 130℃, 150℃, 160℃, 160℃, and 145℃, respectively. Water bath cooling was used, followed by hot roller stretching and shaping. The temperature of the first hot roller was 95℃, the second hot roller was 105℃, and the third hot roller was 25℃; the draw ratios were 4.0 and 1.8, respectively; and the winding speed was 600 m / min.

[0084] The prepared fiber has a strength of 2.5 cN / dtex and a breaking elongation of 150%.

[0085] Example 4

[0086] A method for preparing a low-content, high-performance CMC / PBST composite material includes the following steps:

[0087] Step 1: The preparation method of nano-cellulose crystals is as follows:

[0088] (1) The plant fiber was crushed in a pulverizer and then washed multiple times with anhydrous ethanol. After washing, the fiber was separated and dried at 120°C to obtain plant fiber powder with a particle size of 700 nm.

[0089] (2) The crushed, washed and separated plant fibers are added to a sulfuric acid solution for heating and hydrolysis. After hydrolysis, the fibers are cooled, centrifuged, washed and dried to obtain acid-hydrolyzed powder.

[0090] The concentration of the sulfuric acid solution was 40%, the temperature for hydrolysis was 45℃, the time was 0.5h, and the solid-liquid ratio of the plant fiber to the sulfuric acid solution was 1:10.

[0091] (3) Add glacial acetic acid to the mixture of ethanol and water to adjust the pH to 4.5, then add silane coupling agent, heat and stir until clear to obtain a mixed solution;

[0092] The volume ratio of ethanol to water is 9:1, the silane coupling agent includes KH550 and KH560 in a mass ratio of 1:1, the ratio of the amount of silane coupling agent added to cellulose crystals is 1:3, the heating and stirring temperature is 60℃, and the stirring speed is 650r / min.

[0093] (4) Add the acid-hydrolyzed powder to the mixed solution, heat and stir to complete the silane modification, cool to room temperature, filter, wash and dry to obtain nanocellulose crystals;

[0094] The solid-liquid ratio of the acid-hydrolyzed powder and the mixed solution was 1:5. The heating and stirring temperature was 120℃ for 1 hour. The drying temperature was 85℃ for 10 hours.

[0095] Step 2: Dry PBST (PBST is polybutylene succinate-co-terephthalate with a molecular weight of 20,000 and a polydispersity index of 1.5 produced by BASF New Materials Co., Ltd. in Shanghai), antioxidant 168 and antioxidant 1010, which are commercially available, in a dynamic vacuum drying oven at 80°C for 24 hours.

[0096] Step 3: Add 0.01 wt% (based on the mass of PBST) of liquid paraffin to the dried PBST, stir at high speed, then add 0.5 wt% each of antioxidant 168 and 1010 (based on the mass of PBST), mix thoroughly, pour into a Hacker rheometer, mix at 153℃, rotate at 50 r / min, for 5 min, and then bag the sample after it has cooled naturally.

[0097] Step 4: Thoroughly mix the dried PBST, antioxidant, and 2.0 wt% nanocellulose crystals (based on the mass of PBST), add them to a mixer, and melt the PBST completely at 155°C. Then add 1.0 wt% toluene-2,4-diisocyanate (TDI) to carry out an extrusion blending modification reaction. The speed of the mixer is 50 r / min, and the blending time is 6 min. After drying, the CNC / PBST composite material is obtained and ready for use.

[0098] The prepared CNC / PBST composite material was dried at 90℃ for 6 hours in a dynamic vacuum oven, then pressed into sheets (1 mm thick) and cut into pieces on a flat vulcanizing machine. The mechanical properties were tested according to GB / T 1040.2-2006, and the test results are shown in Table 1.

[0099] Step 5: After thoroughly drying the CNC / PBST composite material, melt spinning was performed. The spinning equipment used was a small twin-screw spinning machine with 5 heating zones: 135℃, 155℃, 165℃, 165℃, and 150℃, respectively. Water bath cooling was followed by hot roller stretching and shaping: the first hot roller temperature was 95℃, the second hot roller temperature was 108℃, and the third hot roller temperature was 30℃; the draw ratios were 4.0 and 1.5, respectively; and the winding speed was 500 m / min.

[0100] The prepared fiber has a strength of 2.3 cN / dtex and a breaking elongation of 165%.

[0101] Example 5

[0102] A method for preparing a low-content, high-performance CMC / PBST composite material includes the following steps:

[0103] Step 1: The preparation method of nano-cellulose crystals is as follows:

[0104] (1) The plant fiber was crushed in a pulverizer and then washed multiple times with anhydrous ethanol. After washing, the fiber was separated and dried at 120°C to obtain plant fiber powder with a particle size of 700 nm.

[0105] (2) The crushed, washed and separated plant fibers are added to a sulfuric acid solution for heating and hydrolysis. After hydrolysis, the fibers are cooled, centrifuged, washed and dried to obtain acid-hydrolyzed powder.

[0106] The concentration of the sulfuric acid solution was 40%, the temperature for hydrolysis was 45℃, the time was 0.5h, and the solid-liquid ratio of the plant fiber to the sulfuric acid solution was 1:10.

[0107] (3) Add glacial acetic acid to the mixture of ethanol and water to adjust the pH to 4.5, then add silane coupling agent, heat and stir until clear to obtain a mixed solution;

[0108] The volume ratio of ethanol to water is 9:1, and the silane coupling agents include KH550, KH560 and KH570 in a mass ratio of 1:1:1. The ratio of the amount of silane coupling agent added to the cellulose crystals is 1:4. The heating and stirring temperature is 60℃ and the stirring speed is 600r / min.

[0109] (4) Add the acid-hydrolyzed powder to the mixed solution, heat and stir to complete the silane modification, cool to room temperature, filter, wash and dry to obtain nanocellulose crystals;

[0110] The solid-liquid ratio of the acid-hydrolyzed powder and the mixed solution was 1:6. The heating and stirring temperature was 120℃ for 2 hours. The drying temperature was 80℃ for 10 hours.

[0111] Step 2: Dry PBST (PBST is polybutylene succinate-co-terephthalate with a molecular weight of 20,000 and a polydispersity index of 3.0 produced by BASF New Materials Co., Ltd. in Shanghai), antioxidant 168 and antioxidant 1010, which are commercially available, in a dynamic vacuum drying oven at 80°C for 24 hours.

[0112] Step 3: Add 0.01 wt% (based on the mass of PBST) of liquid paraffin to the dried PBST, stir at high speed, then add 0.5 wt% each of antioxidant 168 and 1010 (based on the mass of PBST), mix thoroughly, pour into a Hacker rheometer, mix at 153℃, rotate at 50 r / min, for 5 min, and then bag the sample after it has cooled naturally.

[0113] Step 4: Thoroughly mix the dried PBST, antioxidant, and 3.0 wt% nanocellulose crystals (based on the mass of PBST), add them to a mixer, and melt the PBST completely at 160°C. Then add 1.0 wt% toluene-2,4-diisocyanate (TDI) for extrusion blending modification reaction. The speed of the mixer is 40 r / min, and the blending time is 7 min. After drying, the CNC / PBST composite material is obtained and ready for use.

[0114] The prepared CNC / PBST composite material was dried at 90℃ for 6 hours in a dynamic vacuum oven, then pressed into sheets (1 mm thick) and cut into pieces on a flat vulcanizing machine. The mechanical properties were tested according to GB / T 1040.2-2006, and the test results are shown in Table 1.

[0115] Step 5: After thoroughly drying the CNC / PBST composite material, melt spinning was performed. The spinning equipment used was a small twin-screw spinning machine with 5 heating zones: 140℃, 158℃, 167℃, 167℃, and 150℃, respectively. Water bath cooling was followed by hot roller stretching and shaping: the first hot roller temperature was 100℃, the second hot roller temperature was 110℃, and the third hot roller temperature was 30℃; the draw ratios were 3.0 and 1.5, respectively; and the winding speed was 400 m / min.

[0116] The prepared fiber has a strength of 2.1 cN / dtex and a breaking elongation of 175%.

[0117] Comparative Example 1

[0118] The difference from Example 3 is that the PBST material was directly pressed into sheets (1 mm thick) and cut into sheets on a flat vulcanizing machine, and then mechanical property tests were performed.

[0119] Comparative Example 2

[0120] The difference from Example 3 is that no nanocellulose crystals were added.

[0121] Comparative Example 3

[0122] The difference from Example 3 is that the plant cellulose was not acidified with sulfuric acid solution.

[0123] Comparative Example 4

[0124] The difference from Example 3 is that the plant cellulose was not alkylated.

[0125] Comparative Example 5

[0126] The difference from Example 3 is that PBST is polybutylene succinate-co-terephthalate with a molecular weight of 10,000, produced by BASF New Materials Co., Ltd. in Shanghai.

[0127] The test results of the CNC / PBST composite materials prepared in the above examples and comparative examples are shown in Table 1. Figure 1 The figures show the tensile curves of Comparative Examples 1-2 and Examples 3-5. In the figures, 1 is pure PBST of Comparative Example 1, 2 is the composite material prepared in Comparative Example 2, 3 is the composite material prepared in Example 3, 4 is the composite material prepared in Example 4, and 5 is the composite material prepared in Example 5.

[0128] Table 1. Mechanical property test results

[0129]

[0130] Therefore, this invention presents a low-content, high-performance CMC / PBST composite material with the above-mentioned structure, its preparation method, and its application. The tensile strength and elongation at break of the composite material are increased by 100-300% and 50-100% respectively compared with pure PBST, and the melt strength is also improved. At the same time, the spinning process of this composite material is smooth, and the properties of the obtained fiber basically meet the application requirements, which is expected to be applied in the field of fiber manufacturing.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A low-content, high-performance CMC / PBST composite material, characterized in that: It includes nanocellulose crystals, PBST, antioxidants and chain extenders. Nanocellulose crystals are obtained by sequentially crushing, washing, acidifying, alkylating and drying plant fibers. Based on the mass of PBST, the amount of nanocellulose crystals added is 0.5-5.0 wt%, the amount of chain extender added is 0-10 wt%, and the amount of antioxidant added is 0.5-2 wt%.

2. The low-content, high-performance CMC / PBST composite material according to claim 1, characterized in that: Plant fiber is at least one of corn stalks, wheat straw, rice straw, coconut shell fiber, pine needles, and bamboo fiber.

3. The low-content, high-performance CMC / PBST composite material according to claim 1, characterized in that: The preparation method of nano-cellulose crystals is as follows: (1) The crushed, washed and separated plant fibers are added to a sulfuric acid solution for heating and hydrolysis. After hydrolysis, the fibers are cooled, centrifuged, washed and dried to obtain acid-hydrolyzed powder. (2) Add glacial acetic acid to the mixture of ethanol and water to adjust the pH to 4-5, then add silane coupling agent, heat and stir until clear to obtain a mixed solution; (3) Add the acid-hydrolyzed powder to the mixed solution, heat and stir to complete the silane modification, cool to room temperature, filter, wash and dry to obtain nanocellulose crystals.

4. The low-content, high-performance CMC / PBST composite material according to claim 3, characterized in that: In step (1), the concentration of sulfuric acid solution is 35-45%, the temperature of heating and hydrolysis is 40-50℃, the time is 0.5-1h, and the solid-liquid ratio of plant fiber and sulfuric acid solution is 1:(8-12).

5. The low-content, high-performance CMC / PBST composite material according to claim 3, characterized in that: In step (2), the volume ratio of ethanol to water is (8-10):1, the silane coupling agent is at least one of KH550, KH560 or KH570, the ratio of the amount of silane coupling agent added to cellulose crystals is (1-2):(1-5), the heating and stirring temperature is 55-65℃, and the stirring speed is 500-800r / min; In step (3), the solid-liquid ratio of the acid-hydrolyzed powder and the mixed solution is 1:(2-10), the heating and stirring temperature is 110-130℃, and the time is 1-3h.

6. The low-content, high-performance CMC / PBST composite material according to claim 1, characterized in that: PBST has a molecular weight between 10,000 and 100,000 and a polydispersity index of 1.1-4.

0.

7. The low-content, high-performance CMC / PBST composite material according to claim 1, characterized in that: The antioxidants include antioxidant 168 and antioxidant 1010, with a mass ratio of antioxidant 168 to antioxidant 1010 of 1:

1.

8. The low-content, high-performance CMC / PBST composite material according to claim 1, characterized in that: The chain extender is at least one of toluene-2,4-diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane-4,4-diisocyanate, isoflurone diisocyanate, hexamethylene diisocyanate, and maleic anhydride.

9. A method for preparing a low-content, high-performance CMC / PBST composite material according to any one of claims 1-8, characterized in that: Includes the following steps: S1: Vacuum dry PBST and antioxidant to remove moisture, and set aside; S2: Thoroughly mix the dried PBST, antioxidant, and nanocellulose crystals, add them to a mixer, and melt the PBST completely at 140-170℃. Then add the chain extender to carry out an extrusion blending modification reaction. The speed of the mixer is 25-60 r / min, and the blending time is 2-10 min. After drying, the CNC / PBST composite material is obtained and ready for use. S3: The CNC / PBST composite material is melt-spun to obtain biodegradable fibers.

10. The application of a low-content, high-performance CMC / PBST composite material according to any one of claims 1-8 in the textile field.

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