Composite material for optical cable sheath and preparation method of composite material

Abstract

The invention belongs to the technical field of optical cables, and discloses a composite material for an optical cable sheath and a preparation method thereof, and the preparation method comprises the following steps: mixing polylactic acid and polyethylene glycol, heating to a molten state, adding a heat-resistant agent and an auxiliary agent, and continuously heating and stirring to obtain a composite solution; the preparation method comprises the following steps: mixing lignin, epoxy chloropropane and sodium hydroxide, heating and stirring for reaction, and then washing with water to obtain modified lignin; adding the composite solution, the modified lignin and a plasticizer into a solvent, heating and stirring to obtain a composite material solution, adjusting the viscosity of the composite material solution to enable the viscosity to accord with a preset viscosity range of electrostatic spinning, carrying out electrostatic spinning operation to obtain a prefabricated film body, and carrying out hot pressing operation on the prefabricated film body to obtain the composite material for the optical cable sheath. Through the method, the heat resistance and the aging resistance of the composite material for the optical cable sheath are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical cable, in particular to a composite material for optical cable sheath and a preparation method thereof. BACKGROUND

[0002] With the improvement of environmental protection consciousness and the popularization of green communication technology, degradable optical cable sheath composite materials have gradually become a hot spot in the research and application of the optical fiber communication industry. Traditional optical cable sheaths usually use plastic materials, which have good mechanical protection performance, but they are not degradable after use and can easily cause environmental pollution, especially to the optical cable buried in the ground or under the sea for a long time. Therefore, developing degradable optical cable sheath materials has become an important task in the industry. Such materials not only have the physical strength, tensile resistance and corrosion resistance required by traditional optical cable sheaths, but also can be decomposed in the natural environment after the end of service life, thereby reducing the burden on the environment.

[0003] Degradable optical cable sheath composite materials are usually composed of biodegradable polymers and other functional reinforcing materials. The degradability of these composite materials mainly depends on the chemical structure of the material itself and the action of external environment (such as temperature, humidity, ultraviolet light, etc.). For example, polylactic acid (PLA), polyhydroxyalkanoate (PHA) and other biodegradable polymers have been applied in the development of some degradable optical cable sheaths. These materials can be degraded into harmless substances such as water and carbon dioxide in a certain period of time in the natural environment, avoiding the problem of long-term existence of traditional plastic materials in the environment.

[0004] However, biodegradable polymers usually have a low heat distortion temperature, which makes it difficult to meet the requirements of long-term exposure of optical cables in high temperature environments, which makes it prone to material deformation or failure in high temperature areas or long-term high temperature operation environments. At the same time, the lack of anti-aging performance is also one of the challenges faced by degradable optical cable sheath composite materials. Biodegradable materials are prone to degradation reactions when exposed to environmental factors such as ultraviolet light, oxygen and humidity for a long time, which can cause a decline in material performance and even premature failure, making it difficult to meet the demand for long-term stable operation. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a composite material for optical cable sheath and a preparation method thereof, aiming to improve the thermal stability and anti-aging performance of the composite material for optical cable sheath.

[0006] To achieve the above-mentioned purpose, the present application provides a preparation method of a composite material for optical cable sheath, comprising the following steps: S1, mixing polylactic acid and polyethylene glycol and heating to a molten state, adding heat-resistant agent and auxiliary agent and continuing to heat and stir to obtain a composite solution; S2, after mixing the lignin, epichlorohydrin and sodium hydroxide, heating and stirring reaction, then washing with water to obtain modified lignin; S3, the composite solution, modified lignin, plasticizer is added to the solvent, heating, stirring, to obtain the composite material solution, adjust the viscosity of the composite material solution, make it meet the preset viscosity range of electrospinning, electrospinning operation is carried out, to obtain the preform, the preform is hot pressed to obtain the optical cable sheath composite material.

[0007] In some embodiments, the heat-resistant agent in step S1 includes at least one of glass fiber, nano-alumina, nano-zinc oxide, and the auxiliary agent includes at least one of polyvinyl alcohol, polyvinylpyrrolidone and polyacrylamide.

[0008] In some embodiments, the plasticizer in step S3 includes at least one of triethylene glycol dioctanoate, tri (2-ethylhexyl) citrate and glycerol, and the solvent is dichloromethane or chloroform.

[0009] In some embodiments, the step S1 includes: S1.1, the polylactic acid and polyethylene glycol are loaded into the reaction kettle, nitrogen is introduced, and after heating to the molten state, the heat-resistant agent is added, and stirring is carried out for 1-2h to obtain a mixture in the molten state, wherein the mass ratio of polylactic acid and polyethylene glycol is 2-4:1, the flow rate of nitrogen is 1-5L / min, the heating temperature is 160-180℃, and the stirring speed is 300-500rpm; S1.2, the auxiliary agent is added to the molten mixture, and heating and stirring reaction is carried out to obtain a composite solution, wherein the temperature of the molten mixture is 100-120℃, and the addition amount of the auxiliary agent is 5-10% of the mass of the molten mixture.

[0010] In some embodiments, the specific operation of step S2 is: after mixing the lignin, epichlorohydrin and sodium hydroxide in the reaction kettle, heating and stirring reaction is carried out, then washing with water, the washed product is put into the oven to remove water, to obtain modified lignin, wherein the mass ratio of lignin, epichlorohydrin and sodium hydroxide is 1:0.2-0.8:0.5-2, the heating temperature is 100-150℃, the stirring time is 2-4h, and the drying temperature is 50-80℃.

[0011] In some embodiments, the step S3 includes: S3.1, the composite solution, modified lignin and plasticizer are added to the reaction kettle containing solvent, nitrogen is introduced, heating and stirring for 2-3h to obtain a composite material solution, wherein the mass ratio of the composite solution, modified lignin, plasticizer and solvent is 90-95:4-6:0.5-1.5:4-5, the flow rate of nitrogen is 1-5L / min, and the heating temperature is 55-65℃. S3.2, using a viscometer to detect the viscosity of the composite material solution, adjusting the viscosity of the composite material solution until the viscosity of the composite material solution meets the viscosity range of electrospinning.

[0012] If the viscosity is too high, the solution will become too dense, making it difficult to stretch the solution into a filament during electrospinning, which may result in thick fibers or insufficient fiber stretching, thereby affecting the uniformity of the composite material and the fineness of the fibers, and further reducing the performance and biodegradability of the material. On the contrary, if the viscosity is too low, the solution will have too strong fluidity, which may result in excessive dripping or uneven spraying during the spinning process, resulting in loose fiber structure and insufficient strength, thereby affecting the quality and stability of the composite material. Therefore, keeping the composite solution within an appropriate viscosity range is the key to ensuring the smooth progress of the electrospinning process and the excellent performance of the composite material.

[0013] S3.3, loading the composite material solution into the syringe of the electrospinning device, turning on the voltage, and pushing the syringe to inject the composite material solution from the spinning nozzle and deposit it on the collection plate to obtain a preformed film body, wherein the voltage of the electrospinning process is 15-30 kV, the spinning distance is 10-20 cm, and the injection rate is 0.5-1 mL / h; S3.4, placing the preformed film body on a hot press, adjusting the temperature, pressure, and hot pressing time of the hot press, and performing hot pressing operation, and cooling to obtain a composite material for optical cable jacketing.

[0014] In some embodiments, the viscosity of the composite material solution in step S3.2 is adjusted by adding a viscosity adjusting component; The step of adjusting the viscosity of the composite material solution until the viscosity of the composite material solution meets the viscosity range of electrospinning includes: determining whether the viscosity of the composite material solution meets the viscosity range of electrospinning; If yes, proceed to step S3.3; If no, add a viscosity adjusting component to the composite material solution, and execute the steps of using a viscometer to detect the viscosity of the composite material solution and determining whether the viscosity of the composite material solution meets the viscosity range of electrospinning; The viscosity adjusting component includes a thickening agent and a diluent, wherein the thickening agent includes at least one of hydroxypropyl methyl cellulose, polyvinyl alcohol, and carbomer, and the diluent includes at least one of ethanol, dichloromethane, and chloroform.

[0015] In addition, a composite material for optical cable jacketing is also disclosed, which is prepared by the above-mentioned method for preparing a composite material for optical cable jacketing.

[0016] The beneficial effects of the present application are: The glass fiber in the heat-resistant agent can form a reinforced three-dimensional network structure in the composite material by its high strength, rigidity and good thermal stability, preventing the material from deforming or degrading at high temperature. The nano-aluminum oxide and nano-zinc oxide increase the thermal conductivity of the composite material by their small particle size and high specific surface area, helping to evenly distribute heat and avoid local overheating. The surface properties and antioxidant properties of nano-oxides can effectively inhibit the oxidation process of the composite material at high temperature, slowing down the degradation reaction. Adding the additive to the polylactic acid-polyethylene glycol composite material can improve the anti-aging performance of the composite material, reduce the degradation rate of the polylactic acid-polyethylene glycol copolymer during use, and thus improve the durability and long-term performance of the composite material. By modifying lignin with epoxy chloropropane and sodium hydroxide, the lignin molecules undergo crosslinking reaction to form a more stable three-dimensional network structure, effectively enhancing the thermal stability and light resistance of lignin, slowing down the aging effect of ultraviolet light and high temperature environment on the composite material. Secondly, the modified lignin has more functional groups in the molecular chain, making it have stronger antioxidant capacity to resist free radicals and oxidation in the environment, thereby slowing down the degradation rate of the composite material. The addition of plasticizer can introduce more freedom between molecular chains, reduce the interaction force between molecules, make the composite material more flexible and easy to process, and also improve the heat resistance of the composite material. Electrospinning forms ultra-fine fiber structure by stretching the solution into fine fibers under high voltage. This structure has a high specific surface area, which helps to enhance the strength, air permeability and biodegradability of the composite material. At the same time, the precise control in the electrospinning process helps to adjust the diameter and arrangement of the fibers, improving the uniformity and stability of the material. Through hot pressing operation, the uniformity of the composite material is improved, the stability of the composite material is improved, and the mechanical properties of the composite material are enhanced. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is the flowchart of the preparation method of the composite material for optical cable sheath in an embodiment of the present application. DETAILED DESCRIPTION

[0018] In the description of the present application, it should be noted that, in the examples, the specific conditions not specified are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, but are conventional products that can be purchased on the market.

[0019] Please refer to Figure 1 The present application provides a preparation method of a composite material for optical cable sheath, comprising the following steps: S1, mixing polylactic acid and polyethylene glycol and heating to a molten state, adding heat-resistant agent and additive and continuing to heat and stir to obtain a composite solution; The heat-resistant agent in step S1 includes at least one of glass fiber, nano-aluminum oxide, and nano-zinc oxide, and the auxiliary agent includes at least one of polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylamide.

[0020] The glass fiber can form a reinforced three-dimensional network structure in the composite material due to its high strength, rigidity and good thermal stability, and prevent the material from deforming or degrading at high temperature. The nano-aluminum oxide and nano-zinc oxide increase the thermal conductivity of the composite material due to their small particle size and high specific surface area, help the heat to be evenly distributed to avoid local overheating, and the surface properties and oxidation resistance of the nano-oxide can effectively inhibit the oxidation process of the composite material at high temperature and delay the degradation reaction.

[0021] The polyvinyl alcohol can enhance the overall structural stability of the composite material, and it can form hydrogen bonds with the molecular chains in the poly (lactic acid)-poly (ethylene glycol) copolymer to improve the mechanical properties and heat resistance of the composite material. The polyvinylpyrrolidone contains oxygen-containing groups (such as amide groups) in its molecular structure, which can form hydrogen bonds with other components in the composite material to enhance the thermal stability and aging resistance of the composite material. The polyacrylamide has strong hydrophilicity and adhesion, and when used as an auxiliary agent in the poly (lactic acid)-poly (ethylene glycol) copolymer, it can improve the mechanical properties of the composite material by forming hydrogen bonds with the molecular chains of PLA and PEG.

[0022] S1.1, poly (lactic acid) and poly (ethylene glycol) are loaded into a reaction kettle, nitrogen is introduced, and after heating to a molten state, a heat-resistant agent is added and stirred for 1-2 hours to obtain a molten mixture, wherein the mass ratio of poly (lactic acid) to poly (ethylene glycol) is 2-4:1, the flow rate of nitrogen is 1-5 L / min, the heating temperature is 160-180°C, and the stirring speed is 300-500 rpm; The mass ratio of poly (lactic acid) to poly (ethylene glycol) 2-4:1 determines the rigidity and flexibility of the material, and adjusting the ratio can accurately control the performance of the composite material. The nitrogen flow rate of 1-5 L / min can ensure an oxygen-free environment to prevent oxidation and degradation, and the heating temperature is controlled at 160-180°C to ensure complete melting of the material and avoid the influence of too low or too high temperature on the quality. Stirring for 1-2 hours provides sufficient time for the mixture to react uniformly and ensures that the components are fully integrated. The stirring speed of 300-500 rpm promotes uniform mixing and avoids uneven mixing or air bubble problems.

[0023] S1.2, an auxiliary agent is added to the molten mixture, and the mixture is heated and stirred for 1-2 hours to obtain a composite solution, wherein the temperature of the molten mixture is 100-120°C, the amount of the auxiliary agent added is 5-10% of the mass of the molten mixture, and the stirring speed is 300-500 rpm.

[0024] The mixture temperature of 100~120℃ ensures that the material maintains good fluidity at a lower temperature, avoids decomposition of the auxiliary caused by excessively high temperature, and enables the auxiliary to be fully dispersed and reacted, and the auxiliary added in an amount of 5~10% of the quality of the molten mixture helps to optimize the processing performance of the composite solution and the functionality of the final material, and by increasing the proportion of the auxiliary, the stability, fluidity and heat resistance of the material can be improved, thereby improving the processability and performance of the material.

[0025] In an embodiment, when the heat-resistant agent is glass fiber, it is directly mixed with the auxiliary and then added to the molten mixture; when the heat-resistant agent is nano-alumina or nano-zinc oxide, it needs to be dispersed by stirring with part of the solvent and then added to the molten mixture together with the auxiliary.

[0026] S2, the lignin, epoxy chloropropane and sodium hydroxide are mixed and then heated and stirred to react, followed by washing with water to obtain modified lignin; The lignin is modified by epoxy chloropropane and sodium hydroxide to cause cross-linking reaction of the lignin molecules, form a more stable three-dimensional network structure, effectively enhance the thermal stability and light resistance of the lignin, and slow down the aging effect of ultraviolet rays and high temperature environment on the composite material, and secondly, the modified lignin introduces more functional groups into the molecular chain, so that it has stronger antioxidant capacity and can resist free radicals and oxidation in the environment, thereby slowing down the degradation rate of the composite material.

[0027] However, in the modification process of lignin, due to the use of strong alkali-oxidation system, the side chain -OH of lignin is easily oxidized to aldehyde and then further cracked, so that aldehyde substances will appear in the modified lignin, and the aldehyde substances will react with the hydroxyl groups in PEG and the ester bonds in PLA, thereby causing the thermal stability of the composite material to decrease, and the auxiliary added in the present application can avoid this phenomenon, wherein the polyvinyl alcohol interacts with the aldehyde substances in the lignin through its strong hydrophilicity, plays a physical adsorption role, thereby shielding the aldehyde substances and avoiding chemical reaction of the aldehyde substances with the functional groups in the poly-lactic acid or polyethylene glycol, the polyvinylpyrrolidone can effectively reduce the reaction of the aldehyde substances with the ester bonds or hydroxyl groups in the poly-lactic acid-polyethylene glycol copolymer by forming hydrogen bonds with other components in the composite material and adsorbing the aldehyde substances in the modified lignin, the amino and hydroxyl groups in the polyacrylamide molecules can have physical adsorption with the aldehyde substances in the lignin, reduce the opportunity of reaction of the aldehyde substances with the functional groups in other chemical structures such as the hydroxyl groups in PEG and the ester bonds in PLA, thereby preventing the degradation of the composite material in a high temperature environment and enhancing the thermal stability and light resistance of the composite material.

[0028] The specific operation of step S2 is: after mixing lignin, epichlorohydrin and sodium hydroxide in the reaction kettle, heating and stirring reaction is carried out, then washing with water, putting the washed product into the oven to remove water, obtaining modified lignin, wherein the mass ratio of lignin, epichlorohydrin, sodium hydroxide is 1:0.2-0.8:0.5-2, the heating temperature is 100-150℃, the stirring time is 2-4h, and the drying temperature is 50-80℃; The mass ratio of lignin, epichlorohydrin and sodium hydroxide 1:0.2-0.8:0.5-2 helps to promote the effective modification of lignin, ensures the high efficiency of the reaction and the excellent performance of the product, the heating temperature of 100-150℃ ensures that the reaction is carried out under suitable thermal conditions, which helps the effective reaction of epichlorohydrin and lignin, while avoiding side reactions caused by too high temperature, the stirring time of 2-4h ensures the full reaction, so that the lignin can be fully modified to obtain uniform product, and the drying removes water to ensure the drying and stability of the modified lignin, avoiding thermal degradation caused by too high temperature.

[0029] S3, the composite solution, modified lignin and plasticizer are added to the solvent, heated and stirred to obtain a composite material solution, the viscosity of the composite material solution is adjusted to meet the preset viscosity range of electrospinning, electrospinning is performed, and an optical cable sheath composite material is obtained.

[0030] In step S3, the plasticizer includes at least one of triethylene glycol dioctanoate, tri(2-ethylhexyl) citrate and glycerol, and the solvent is dichloromethane or chloroform.

[0031] The addition of plasticizer can introduce more freedom between molecular chains, reduce the interaction force between molecules, make the composite material more flexible, easy to process, and also improve the heat resistance of the composite material; and electrospinning can stretch the solution into a filament by high voltage to form a superfine fiber structure, which has a high specific surface area, helps to enhance the strength, air permeability and biodegradability of the composite material, and at the same time, the precise control in the electrospinning process helps to adjust the diameter and arrangement of the fiber, improve the uniformity and stability of the material.

[0032] S3.1, the composite solution, modified lignin and plasticizer are added to the reaction kettle containing solvent, nitrogen is introduced, heated and stirred for 2-3h to obtain a composite material solution, wherein the mass ratio of the composite solution, modified lignin, plasticizer and solvent is 90-95:4-6:0.5-1.5:4-5, the nitrogen flow is 1-5L / min, and the heating temperature is 55-65℃; The mass ratio of the composite solution, modified lignin, plasticizer, and solvent is 90-95:4-6:0.5-1.5:4-5, which ensures the reasonable proportioning between the components, helps the uniformity and stability of the solution, and ensures that the performance of the composite material meets the expected requirements; 1-5 L / min of nitrogen is used to remove moisture and oxygen in the air, to avoid oxidation of the solution, and to help improve the flowability and reactivity of the solution; the heating temperature is kept in the range of 55-65℃, so that the solution is fully mixed without excessive heating, and the dissolution and reaction of the components are promoted; the stirring time is 2-3 h, which ensures that all the components are fully mixed and reacted, and the composition of the composite material solution is uniform, providing a high-quality solution basis for the subsequent electrospinning process.

[0033] S3.2, the viscosity of the composite solution is detected using a viscometer, and the viscosity of the composite solution is adjusted until the viscosity of the composite solution meets the viscosity range of electrospinning; If the viscosity is too high, the solution will become too dense, making it difficult to stretch the solution into a filament during electrospinning, which may result in thick fibers or insufficient fiber stretching, affecting the uniformity of the composite material and the fineness of the fibers, and thus reducing the performance and biodegradability of the material; on the contrary, if the viscosity is too low, the solution has too strong flowability, and too much dripping or uneven spraying may occur during the spinning process, resulting in loose fiber structure and insufficient strength, affecting the quality and stability of the composite material, therefore, keeping the composite solution within the appropriate viscosity range is the key to ensuring the smooth progress of the electrospinning process and the excellent performance of the composite material.

[0034] The viscosity of the composite solution is adjusted by adding a viscosity-adjusting component; The step of adjusting the viscosity of the composite solution until the viscosity of the composite solution meets the viscosity range of electrospinning includes: determining whether the viscosity of the composite solution meets the viscosity range of electrospinning; If yes, proceed to step S3.3; If no, add a viscosity-adjusting component to the composite solution, and perform the steps of detecting the viscosity of the composite solution using a viscometer and determining whether the viscosity of the composite solution meets the viscosity range of electrospinning, wherein the viscosity-adjusting component includes a thickening agent and a diluent, the thickening agent includes at least one of hydroxypropyl methyl cellulose, polyvinyl alcohol, and carbomer, and the diluent includes at least one of ethanol, dichloromethane, and chloroform.

[0035] S3.3, the composite solution is loaded into a syringe of an electrospinning device, the voltage is turned on, and the syringe is pushed to inject the composite material solution from the spinning nozzle, which is deposited on a collection plate to obtain a preformed film body, wherein the voltage of the electrospinning process is 15-30 kV, the spinning distance is 10-20 cm, and the injection rate is 0.5-1 mL / h.

[0036] The voltage in the electrospinning process directly affects the stretching effect of the solution, and a high voltage can effectively draw the composite material solution into a thin filament, forming a nanoscale fiber structure, increasing the specific surface area and strength of the composite material, and enhancing its degradability. The spinning distance of 10-20 cm determines the deposition quality of the fiber. A suitable distance helps the fiber to be fully stretched in the air, ensuring that the fiber is fine and uniformly deposited on the collection plate, so as to obtain a composite material with uniform structure and stable performance. The injection rate of 0.5-1 mL / h controls the flow rate of the solution. Too fast injection rate may result in insufficient fiber fineness, affecting the uniformity and performance of the composite material, while too slow rate may affect the production efficiency. Therefore, it is necessary to maintain an appropriate injection rate within this range to ensure efficient and high-quality composite material preparation.

[0037] In an embodiment, in order to ensure the smooth progress of electrospinning, the following formula is designed to control the viscosity of the composite material solution: ; wherein η v , η i , η q are the partial viscosities (mPa·s), V is the voltage (kV), I is the spinning distance (cm), Q is the injection rate (mL / h), and η is the viscosity of the composite material solution (mPa·s).

[0038] In order to meet the requirements of electrospinning, h is the voltage sensitivity coefficient (mPa·s / kV), which is determined by fixing the spinning distance and the injection rate, fitting the linear regression equation η v -V, and the slope of the equation. In this embodiment, the spinning distance is 15 cm, the injection rate is 0.8 mL / h, and the voltage is 15-30 kV. At least five voltage values within the range are selected for testing, each test is repeated three times, and the average value is taken. The calculation shows that the value of h is in the range of 50-150, and B is the viscosity reference value (mPa·s) corresponding to zero voltage, which is in the range of -500-500. A is the distance attenuation coefficient (mPa·s·cm), which is calculated by fixing the voltage and the injection rate, fitting the equation η i -I, and determined by the slope of the equation. In this embodiment, η i is obtained by testing the experimental composite material solution with a viscosity tester, the spinning distance is 10-20 cm, at least five spinning distance values within the range are selected for testing, each test is repeated three times, and the average value is taken. The calculation shows that the value of A is in the range of 10000-50000. m is the rate response coefficient (mPa·s), which is calculated by fixing the voltage and the spinning distance, fitting the curve equation η qIn this embodiment, the voltage is 25 kV, the spinning distance is 15 cm, the injection rate is 0.5-1 mL / h, and at least five injection rate values are selected in the range for testing, each group of tests is repeated three times, and the average value is taken. It can be calculated that the value range of m is -1000 to -400. α, β, γ are dimensionless weight coefficients, and the dimensionless difference is eliminated and the parameter sensitivity is quantified by the coefficient of variation method. The weight equation set is solved by combining the response surface method to obtain α, the value range of which is 0.35-0.50, the value range of β is 0.25-0.40, the value range of γ is 0.20-0.35, and α+β+γ=1.

[0039] In an embodiment, h=100 mPa·s / kV, B=0 mPa·s, A=30000 mPa·s·cm, and m=-700 mPa·s. By substituting the values of voltage, spinning distance, and injection rate, the viscosity range of the composite material solution is 3000-6485.2 mPa·s.

[0040] In an embodiment, for the composite material of the optical cable sheath, sufficient fiber strength, i.e., tensile strength, can ensure that the composite material does not break prematurely or lose function during its degradation process, thereby prolonging its use time in the environment. Therefore, the tensile strength should be as large as possible without affecting the degradation of the composite material. The tensile strength is related to the porosity of the material, and the porosity of the material is related to the diameter of the material fiber. To obtain the relationship between the porosity and the tensile strength, the following formula is designed for calculation: ; where σ is the tensile strength of the material (MPa), σ0 is the tensile strength of the material when the porosity is zero (MPa), which is measured by a standard tensile tester. Through a large number of experimental tests, when the tensile strength reaches 48-63 MPa, the requirement is met, i.e., the value range of σ is 48-63 MPa, and σ0=70 MPa; n is a constant, dimensionless, which is obtained by testing the tensile strength data of samples with different porosities, and then fitting the experimental data using the least squares method, the value range of n is 1-3, and ϕ is the porosity of the material (%); V is the total volume of the composite material (cm 3 ), which is tested by the Archimedes drainage method, and the value range of V is 1-10; L is the total length of the fiber in the composite material (m), which is measured by clamping the fiber bundle at both ends in the clamps of a universal testing machine without damaging the fiber, and then stretching the fiber bundle until it is completely straightened. The value range of L is 0.6-8; d is the fiber diameter (mm).

[0041] In an embodiment, σ = 48 ~ 63 MPa, σ0 = 70 MPa, n = 2, V = 5 cm 3 , L = 4 m, the porosity of the composite material is 5.1 ~ 17.2%, and the diameter of the nozzle is 1.15 ~ 1.23 mm.

[0042] S3.4, place the preformed film body on the hot press, adjust the temperature, pressure and hot pressing time of the hot press, and perform hot pressing operation, and cool down to obtain a composite material for cable sheath, wherein the hot pressing temperature is 150 ~ 180℃, the hot pressing pressure is 1 ~ 5MPa, and the hot pressing time is 5 ~ 10min; The hot pressing temperature is set between 150 ~ 180℃, which helps to fully soften the material and recombine the molecular chains, thereby improving the formability and uniformity of the composite material; the hot pressing pressure of 1 ~ 5MPa can effectively promote the fusion between molecules, enhance the mechanical strength and durability of the composite material, and at the same time avoid the rupture or deformation of the material caused by excessive pressure; the hot pressing time is controlled within 5 ~ 10 minutes, which helps to ensure uniform heating during the hot pressing process, so that the composite material maintains good degradability while having the required composite material structure and stability; The composite material for cable sheath is suitable for server rooms. In the server room, due to the intensive operation of high-power equipment, the insufficient efficiency of the heat dissipation system, and the disorder of the cold and hot air flow organization, local temperature accumulation phenomenon occurs, which causes the temperature of the environment to exceed the safety threshold of the server, resulting in high temperature deformation of the traditional cable sheath. The composite material for cable sheath prepared by the present application builds a stable three-dimensional skeleton structure by adding heat-resistant agent and modified lignin, effectively inhibits thermal deformation and improves thermal conductivity, so that the material can still maintain good thermal stability in a high temperature environment; at the same time, the humidity in the server room needs to be strictly controlled to prevent corrosion of the circuit board, metal parts and connectors, and the environmental humidity is usually maintained at a low level. This condition is exactly conducive to avoiding hydrolytic degradation of the composite material and causing damage to the composite material, so the composite material for cable sheath of the present application can be applied to the server room.

[0043] In an embodiment, when the composite material for cable sheath is placed in airtight environment, the composite material for cable sheath has the functional requirement of air tightness, and a filling liquid can be coated on the surface of the composite material to improve the air tightness of the composite material for cable sheath, and S3.4 can be changed to: S3.4, place the preformed film body on the hot press, then coat the filling liquid, adjust the temperature, pressure and hot pressing time of the hot press, and perform hot pressing operation, and cool down to obtain a composite material for cable sheath, wherein the amount of filling liquid added is 10 ~ 20% of the mass of the preformed film body, the hot pressing temperature is 150 ~ 180℃, the hot pressing pressure is 1 ~ 5MPa, and the hot pressing time is 5 ~ 10min.

[0044] The filling liquid is a dichloromethane or chloroform solution with a mass concentration of 3-8% of a filler, wherein the filler includes at least one of polylactic acid, polybutylene succinate, and polyhydroxyalkanoate; The filling liquid can effectively fill the pores of the membrane under the action of high temperature and pressure, and as the polylactic acid, polybutylene succinate, and polyhydroxyalkanoate in the filling liquid solidify, the density of the composite material increases, effectively preventing the penetration of gas and other substances; at the same time, the penetration of the liquid during the hot-pressing process can also improve the uniformity of the membrane, avoid uneven distribution of the material, thereby improving the stability of the composite material and prolonging the service life thereof.

[0045] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A method for producing a composite material for optical cable sheaths, characterized by, The method comprises the following steps: S1, mixing polylactic acid and polyethylene glycol and heating to a molten state, adding a heat-resistant agent and an auxiliary agent and continuing to heat and stir to obtain a composite solution; S2, mixing lignin, epichlorohydrin and sodium hydroxide and then heating and stirring to react, and then washing with water to obtain modified lignin; S3, adding the composite solution, the modified lignin and a plasticizer to a solvent, heating and stirring to obtain a composite material solution, adjusting the viscosity of the composite material solution to make it meet the preset viscosity range of electrospinning, and performing electrospinning to obtain a preformed film, and then performing hot pressing on the preformed film to obtain a composite material for optical cable sheath.

2. The method for preparing a composite material for optical cable sheaths according to claim 1, characterized in that, The heat-resistant agent in the step S1 comprises at least one of glass fiber, nano-aluminum oxide and nano-zinc oxide, and the auxiliary agent comprises at least one of polyvinyl alcohol, polyvinylpyrrolidone and polyacrylamide.

3. The method for preparing a composite material for optical cable sheaths according to claim 1, characterized in that, The plasticizer in the step S3 comprises at least one of triethylene glycol dioctanoate, tri(2-ethylhexyl) citrate and glycerol, and the solvent is dichloromethane or chloroform.

4. The method of claim 1 or 2, wherein the composite material is prepared by the steps of: a) mixing the components of the composite material; b) extruding the mixture into a sheet; c) calendering the sheet; d) extruding the calendered sheet into a tube; and e) curing the tube. The step S1 comprises: S1.1, loading polylactic acid and polyethylene glycol into a reaction kettle, introducing nitrogen, heating to a molten state, adding a heat-resistant agent, and stirring for 1-2 hours to obtain a molten mixture, wherein the mass ratio of polylactic acid to polyethylene glycol is 2-4:1, the flow rate of nitrogen is 1-5 L / min, the heating temperature is 160-180°C, and the stirring speed is 300-500 rpm; S1.2, adding an auxiliary agent to the molten mixture, and heat-stirring for 1-2 hours to obtain a composite solution, wherein the temperature of the molten mixture is 100-120°C, the addition amount of the auxiliary agent is 5-10% of the mass of the molten mixture, and the stirring speed is 300-500 rpm.

5. The method for preparing a composite material for optical cable sheaths according to claim 1, characterized in that, The specific operation of the step S2 is: after lignin, epichlorohydrin and sodium hydroxide are added to a reaction kettle and mixed, heating and stirring are performed to react, and then washing with water is performed, the product washed out is placed in an oven to remove water, and modified lignin is obtained, wherein the mass ratio of lignin, epichlorohydrin and sodium hydroxide is 1:0.2-0.8:0.5-2, the heating temperature is 100-150°C, the stirring time is 2-4 hours, and the drying temperature is 50-80°C.

6. The method for preparing a composite material for optical cable sheaths according to claim 1, characterized in that, The step S3 comprises: S3.1, adding the composite solution, the modified lignin and the plasticizer to a reaction kettle containing a solvent, introducing nitrogen, heating and stirring for 2-3 hours to obtain a composite material solution, wherein the mass ratio of the composite solution, the modified lignin, the plasticizer and the solvent is 90-95:4-6:0.5-1.5:4-5, the flow rate of nitrogen is 1-5 L / min, and the heating temperature is 55-65°C; S3.2, detecting the viscosity of the composite material solution using a viscometer, and adjusting the viscosity of the composite material solution until the viscosity of the composite material solution meets the viscosity range of electrospinning; S3.3, loading the composite material solution into a syringe of the electrospinning device, turning on the voltage, pushing the syringe to inject the composite material solution from the spinning nozzle, depositing on the collection plate to obtain a preform, wherein the voltage of the electrospinning process is 15-30 kV, the spinning distance is 10-20 cm, and the injection rate is 0.5-1 mL / h; S3.4, placing the preform on a hot press, adjusting the temperature, pressure and hot pressing time of the hot press, performing hot pressing operation, cooling to obtain a composite material for cable sheath, wherein the hot pressing temperature is 150-180℃, the hot pressing pressure is 1-5 MPa, and the hot pressing time is 5-10 min.

7. The method for preparing a composite material for optical cable sheaths according to claim 6, characterized in that, The viscosity of the composite material solution in step S3.2 is adjusted by adding a viscosity adjusting component; The step of adjusting the viscosity of the composite material solution until the viscosity of the composite material solution meets the electrospinning viscosity range comprises: determining whether the viscosity of the composite material solution meets the electrospinning viscosity range; if yes, then performing step S3.3; if no, then adding a viscosity adjusting component to the composite material solution, and performing the steps of detecting the viscosity of the composite material solution using a viscometer and determining whether the viscosity of the composite material solution meets the electrospinning viscosity range; The viscosity adjusting component comprises a thickening agent and a diluent, wherein the thickening agent comprises at least one of hydroxypropyl methyl cellulose, polyvinyl alcohol and carbomer, and the diluent comprises at least one of ethanol, dichloromethane and chloroform.

8. A composite material for optical cable jacketing, characterized by, The composite material for cable sheath is prepared by the method of any one of claims 1-7, and the auxiliary agent is used to treat the aldehyde product of modified lignin.

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