阅读说明：本技术 一种碳纤维原丝中钠离子含量测定方法 (Method for measuring content of sodium ions in carbon fiber precursor ) 是由 王斐 赵红霞 吴延洲 于 2018-08-23 设计创作，主要内容包括：本发明涉及碳纤维原丝技术领域的一种碳纤维原丝中钠离子含量测定方法。所述测定方法可包括以下步骤：(1)取纤维置于容器中准确称重；(2)对纤维灼烧灰化,得到样品,待降温后将样品取出放入干燥器中冷却至室温；(3)吸取酸试剂浸泡样品,后将溶液移至容量瓶中；用高纯水冲洗容器,将溶液全部转移至容量瓶中定容,得到待测溶液；(4)对待测溶液中钠离子含量进行测定,并计算纤维中钠离子含量；本发明的方法可以在8小时内测出纤维原丝中钠离子的结果,可以指导甲酸清洗工艺中甲酸的浓度、流量的调整,从而将纤维原丝中的钠离子残留量保持在一个稳定,可接受的范围。(The invention relates to a method for measuring the content of sodium ions in carbon fiber precursors in the technical field of carbon fiber precursors. The assay method may comprise the steps of: (1) placing the fiber in a container and accurately weighing; (2) burning and ashing the fibers to obtain a sample, taking out the sample after cooling, and putting the sample into a dryer for cooling to room temperature; (3) absorbing an acid reagent to soak a sample, and then transferring the solution to a volumetric flask; washing the container with high-purity water, and transferring all the solution into a volumetric flask for constant volume to obtain a solution to be measured; (4) measuring the content of sodium ions in the solution to be measured, and calculating the content of sodium ions in the fibers; the method can measure the sodium ion result in the fiber precursor within 8 hours, and can guide the adjustment of the concentration and the flow of the formic acid in the formic acid cleaning process, so that the residual amount of the sodium ion in the fiber precursor is kept in a stable and acceptable range.)

1. A method for measuring the content of sodium ions in carbon fiber precursors comprises the following steps:

(1) placing the fiber in a container and accurately weighing;

(2) burning and ashing the fibers to obtain a sample, taking out the sample after cooling, and putting the sample into a dryer for cooling to room temperature;

(3) absorbing an acid reagent to soak a sample, and then transferring the solution to a volumetric flask; then flushing the container with high-purity water, and transferring all the solution into a volumetric flask for constant volume to obtain a solution to be measured;

(4) measuring the content of sodium ions in the solution to be measured, and calculating the content of sodium ions in the fibers;

wherein the ratio of the volume dosage of the acid reagent in the step (3) to the mass of the fiber in the step (1) is 7-50 mL/g.

2. The method for measuring the content of sodium ions in carbon fiber precursors according to claim 1, comprising the steps of:

in the step (1), the mass amount of the fiber is 0.5-2 g, preferably 0.75-0.85 g;

in the step (3), the volume consumption of the acid reagent is 15-25 mL, and the concentration of the acid reagent is 0.9-1.1 mol/L.

3. The method for measuring the content of sodium ions in carbon fiber precursors according to claim 1, comprising the steps of:

pre-ashing the fibers before the fiber burning and ashing step; the pre-ashing comprises the following steps: gradually raising the temperature to heat the container until no smoke emerges, wherein the pre-ashing maximum temperature is not more than 800 ℃.

4. The method for measuring the content of sodium ions in carbon fiber precursors according to claim 1, comprising the steps of:

in the step (2), the ignition temperature is 790-810 ℃, and the ignition time is not less than 30 min.

5. The method for measuring the content of sodium ions in carbon fiber precursors according to claim 1, comprising the steps of:

the container is selected from a platinum crucible;

the acid reagent is selected from nitric acid.

6. The method for measuring the content of sodium ions in carbon fiber precursors according to claim 1, comprising the steps of:

in step (1), the weighing is accurate to 0.0001 g.

7. The method for measuring the content of sodium ions in carbon fiber precursors according to claim 1, comprising the steps of:

the calculation comprises the following steps:

the sodium ion content X, expressed in ppm, is calculated according to the following formula:

in the formula:

m is the content of sodium ions in the solution to be detected, mg/L;

v-volume of the solution to be measured, L;

m₁-mass of the fiber, g.

8. The method for measuring the content of sodium ions in the carbon fiber precursor according to any one of claims 1 to 7, characterized by comprising the steps of:

(1) putting 0.5-2 g of fibers into a container and accurately weighing;

(2) burning and ashing the fibers, setting the burning temperature to be 790-810 ℃, preferably 800 ℃, and setting the burning time to be not less than 30min to obtain a sample, taking out the sample after cooling, and putting the sample into a dryer for cooling to room temperature;

(3) absorbing nitric acid to soak a sample, and transferring the solution to a 100mL volumetric flask after waiting for 10-30 min; then flushing the container with high-purity water, and transferring all the solution into a 100mL volumetric flask for constant volume to obtain a solution to be measured;

(4) and (4) measuring the content of sodium ions in the solution to be measured, and calculating the content of sodium ions in the fibers.

9. The method for measuring the sodium ion content in the carbon fiber precursor according to claim 8, wherein:

in the step (3), 20mL of 1.0mol/L nitric acid is sucked for soaking the sample.

10. The method for measuring the sodium ion content in the carbon fiber precursor according to claim 8, wherein:

the calculation comprises the following steps:

the sodium ion content X, expressed in ppm, is calculated according to the following formula:

in the formula:

m is the content of sodium ions in the solution to be detected, mg/L;

0.1-the volume of the solution to be measured is 0.1L;

m₁-mass of the fiber, g.

Technical Field

The invention relates to the technical field of carbon fiber precursors, and in particular relates to a method for measuring the content of sodium ions in carbon fiber precursors.

Background

The carbon fiber precursor is a main raw material for producing carbon fibers, a large amount of sodium ions are remained in the precursor (polyacrylonitrile-based fiber) produced by a sodium thiocyanate method, and the content of the remained sodium ions needs to be accurately and quickly measured in the production process of the carbon fiber precursor.

At present, a plurality of methods for measuring sodium ions exist, but a method for quickly measuring the sodium ions of the carbon fiber precursors is not found, and the content of the sodium ions in the precursors can be quickly mastered, so that the process can be adjusted at any time.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a method for measuring the content of sodium ions in carbon fiber precursors. The method shortens the measurement time as much as possible, can quickly measure the residual quantity of sodium ions in the carbon fiber precursor, can obtain results within 24 hours (8 hours as fast as possible), and can master the content of the sodium ions in the precursor at the fastest speed, thereby quickly adjusting the processes before and during the production of the precursor.

The method for measuring the content of sodium ions in the carbon fiber precursor can comprise the following steps:

(1) accurately weighing the fiber in a container (to the accuracy of 0.0001 g);

(2) burning and ashing the fibers to obtain a sample, taking out the sample after cooling, and putting the sample into a dryer for cooling to room temperature; completely ashing to remove organic matters;

(3) absorbing an acid reagent to soak a sample, and then transferring the solution to a volumetric flask; washing the container with high-purity water, and transferring all the solution into a volumetric flask for constant volume to obtain a solution to be measured;

(4) measuring the content of sodium ions in the solution to be measured, and calculating the content of sodium ions in the fibers;

wherein the ratio of the volume dosage of the acid reagent in the step (3) to the mass of the fiber in the step (1) is 7-50 mL/g.

Preferably, the first and second electrodes are formed of a metal,

the container may be selected from a platinum crucible.

In the step (1), the dosage of the fiber can be 0.5-2 g, preferably 0.75-0.85 g (the error is small, and the processing time is moderate); in the step (3), the volume consumption of the acid reagent is 15-25 mL.

In the step (2), the burning temperature can be 790-810 ℃, preferably 800 ℃, and the burning time is not less than 30min (in order to eliminate system errors, the burning time in each experiment is preferably consistent).

In step (3), the acid reagent may be selected from nitric acid. (other acids commonly used in the art may also be used, preferably nitric acid)

In the step (3), the concentration of the acid reagent is 0.9-1.1 mol/L.

In step (4), the calculating may include the steps of:

the sodium ion content X, expressed in ppm, is calculated according to the following formula:

in the formula:

m is the content of sodium ions in the solution to be detected obtained by ion chromatography, mg/L;

v-volume of the solution to be measured, L;

m₁-mass of the fiber, g.

Specifically, the method for measuring the content of sodium ions in the carbon fiber precursor can comprise the following steps:

(1) preparing a dry constant-weight platinum crucible, weighing 0.5-2 g (accurate to 0.0001g) of fiber in the crucible, accurately weighing, wherein the fiber cannot be directly contacted with hands in the sampling and weighing processes, and the operation is carried out by wearing gloves; (the amount of the nitric acid is adjusted according to the content of sodium ions, but the amount of the nitric acid can be fixed at 20mL to eliminate the error of the substrate system)

(2) Burning and ashing the fibers, specifically, pre-ashing can be carried out firstly, namely, the temperature is gradually increased to heat the platinum crucible until no smoke is emitted, and the highest pre-ashing temperature is not more than 800 ℃; then placing the platinum crucible with a cover into a muffle furnace, setting the temperature to be 800 ℃, starting timing when the temperature of the muffle furnace rises to 800 ℃, drying for 45min at 800 ℃ to obtain a sample, taking out the sample after cooling, and placing the sample into a dryer for cooling to room temperature;

(3) sucking 20mL of 1.0mol/L nitric acid into a platinum crucible (used as a solvent, the dosage and concentration of the nitric acid are fixed in order to eliminate the base error of long-term operation) to soak a sample, and transferring the solution into a 100mL volumetric flask after waiting for 15 min; washing the platinum crucible with high-purity water, and transferring all the solution obtained after washing to the 100mL volumetric flask for constant volume to obtain a solution to be measured;

(4) washing a sample bottle (2-3 times) with a small amount of solution to be detected, taking about 5mL of solution to be detected into the sample bottle, and covering a sample cover to avoid pollution;

(5) and (3) measuring the sodium ion content of the solution to be measured by using ion chromatography, and calculating the sodium ion content in the fiber.

The calculation comprises the following steps:

the sodium ion content X, expressed in ppm, is calculated according to the following formula:

in the formula:

m is the content of sodium ions in the solution to be detected obtained by ion chromatography, mg/L;

0.1-the volume of the solution to be measured is 0.1L;

m₁-mass of fiber, g.

In the test method, in sample preparation, a gradual heating direct ashing method (instead of the traditional method of firstly acidifying and evaporating to dryness and then completely ashing) is adopted during pretreatment and pre-ashing, then ashing is carried out at a fixed temperature, and then single acid is used for dissolving, so that the simplicity of a substrate is ensured, the excellent peak shape during ion chromatographic determination is ensured, the integral error is reduced, and the time is saved greatly due to the reduction of steps and is more environment-friendly. The testing method simplifies the steps, is environment-friendly, saves time and has no influence on the accuracy on the basis of ensuring complete reaction; the method has good repeatability, high accuracy and high speed, can measure the result of the sodium ions in the fiber protofilament within 24 hours (8 hours at the fastest), and can guide the adjustment of the concentration and the flow of the formic acid in the formic acid cleaning process, thereby keeping the residual quantity of the sodium ions in the protofilament within a stable and acceptable range.

Detailed Description

The present invention will be further described with reference to the following examples. However, the present invention is not limited to these examples.