硫酸环境下电流强度对碳纤维表面电化学活化的影响

马崇攀; 张洋; 张恒; 高爱君; 王宇

doi:10.13801/j.cnki.fhclxb.20230822.002

硫酸环境下电流强度对碳纤维表面电化学活化的影响

doi: 10.13801/j.cnki.fhclxb.20230822.002

马崇攀¹,
张洋¹,
张恒¹,
高爱君^{1, 2},
王宇^{1, 2, ,}

1.
北京化工大学　材料科学与工程学院，北京 100029
2.
碳纤维及功能高分子教育部重点实验室，北京 100029

详细信息

通讯作者:
王宇，博士，副教授，硕士生导师，研究方向为聚丙烯腈基碳纤维及其复合材料　E-mail: wangy@mail.buct.edu.cn

中图分类号: TB332
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出版历程
- 收稿日期: 2023-07-05
- 修回日期: 2023-07-31
- 录用日期: 2023-08-03
- 网络出版日期: 2023-08-22
- 刊出日期: 2024-04-01

Effect of current intensity on electrochemical activation of carbon fibers surface in sulfuric acid environment

MA Chongpan¹,
ZHANG Yang¹,
ZHANG Heng¹,
GAO Aijun^{1, 2},
WANG Yu^{1, 2
, ,}

1.
School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
2.
Key Laboratory of Carbon Fiber and Functional Polymer, Ministry of Education, Beijing 100029, China

摘要

摘要: 碳纤维的碳含量在90%以上，表面惰性强，表面活化处理是其制备过程中的重要工艺。研究采用XPS、Raman、动态接触角、单丝拉伸和界面剪切强度等测试方法，借助非接触式阳极氧化装置，明确了稀H₂SO₄作为电解液时电流强度对电化学活化碳纤维表面结构和性能的影响。结果表明：活性氧[O]进攻碳纤维表面使其含氧活性官能团含量增加，在本研究范围内电流越大活化效果越显著；处于阳极附近的碳纤维，受静电与扩散作用影响，SO₄ ²⁻和S₂O₈ ²⁻进入碳结构内部间隙，碳纤维表面S/C升高，直径增大。在SO₄ ²⁻刻蚀作用下，碳纤维表面无序碳结构脱落而缺陷减少，石墨化程度降低；SO₄ ²⁻和S₂O₈ ²⁻插层进入碳结构内部，通过静电作用形成缔合结构，在刻蚀和插层的共同作用下，碳纤维的单丝拉伸强度提升，最高提高了16.77%。0.5 A电流处理后，碳纤维表面粗糙度提升，表面可与环氧树脂基体反应的羟基、羧基官能团含量最高，碳纤维表面极性最强，与去离子水的动态接触角由未处理时的89.9°降低到50.6°，相应的复合材料界面剪切强度提高了47.70%。
- 碳纤维 /
- 电化学活化 /
- 表面结构 /
- 稀硫酸 /
- 活性氧[O]
Abstract: Carbon fibers with a carbon content of over 90% have the characteristic of strong surface inertness, so surface activation treatment is an essential process in their preparation. The effect of current intensity on the physicochemical structure and properties of electrochemically activated carbon fiber surface under dilute H₂SO₄ electrolyte were explored by XPS, Raman, dynamic contact angle, monofilament tensile strength and interfacial shear strength, and non-contact anodizing device was used. The results show that the content of oxygen-containing functional groups increases by the attack of reactive oxygen [O] on the surface of carbon fibers, and the activation effect is significant with increasing current within the scope of this study. Carbon fibers near the anode are affected by static electricity and diffusion. SO₄ ²⁻ and S₂O₈ ²⁻ enter the internal gap of carbon structure, so the surface S/C and diameter of carbon fibers increase. Under the action of SO₄ ²⁻ etching, the disordered carbon structure on the surface of carbon fiber fell off, the degree of graphitization decreases. SO₄ ²⁻ and S₂O₈ ²⁻ are intercalated into the carbon structures, forming an associated structure through electrostatic interaction. Under the combined effect of etching and intercalation, the monofilament tensile strength of carbon fibers has been improved, with a maximum increase of 16.77%. After 0.5 A current treatment, the surface roughness of carbon fiber is improved, the content of hydroxyl and carboxyl functional groups on the carbon fiber surface that can react with the epoxy resin matrix is the highest, the surface polarity of carbon fiber is the strongest, the dynamic contact angle with deionized water is reduced from 89.9° of untreated to 50.6°, and the corresponding interfacial shear strength of the composite is increased by 47.70%.
- carbon fiber /
- electrochemical activation /
- surface structure /
- dilute sulfuric acid /
- reactive oxygen [O]

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图 1 非接触式电化学氧化处理装置示意图

Figure 1. Schematic diagram of a non-contact electrochemical treatment unit

CF—Carbon fiber

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图 2 (a) 复合材料界面评价装置；碳纤维表面树脂微滴的脱粘过程：(b) 脱粘前；(c) 脱粘后

Figure 2. (a) Composite interface evaluation device; Debonding process of epoxy microdroplet on carbon fiber surface: (b) Before debonding;(c) After debonding

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图 3 不同电流处理后碳纤维的XPS全谱图

Figure 3. XPS full spectra of carbon fiber after different current treatment

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图 4 不同电流强度处理后碳纤维表面O/C比

Figure 4. Oxygen-carbon element ratio of carbon fiber treated with different current intensities

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图 5 不同电流处理后碳纤维的XPS的C1s分峰拟合

Figure 5. C1s curves fitting for XPS of carbon fiber after different current treatment

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图 6 不同电流强度处理后的碳纤维的S/C比

Figure 6. Sulfur-carbon elemental ratio of carbon fiber treated with different current intensities

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图 7 碳纤维直径随电流强度变化

Figure 7. Variation of carbon fiber diameter with current intensity

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图 8 硫酸溶液电化学处理碳纤维直径胀大机制示意图

Figure 8. Schematic diagram of the expansion mechanism of carbon fiber diameter expansion treated by sulfuric acid solution electrochemically

d, d'—Carbon fiber diameter before and after intercalation; GIC—Graphite intercalation on compounds; e⁻—Electron

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图 9 不同电流强度处理后碳纤维表面拉曼光谱与石墨化程度R值

Figure 9. Raman spectra and the degree of graphitization R values of carbon fibers treated with different current intensities

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图 10 接触角测试(a)和不同电流强度处理后的碳纤维表面与去离子水的动态接触角(b)

Figure 10. Contact angle test process (a) and dynamic contact angle between carbon fiber surface treated with different current intensities and deionized water (b)

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图 11 不同电流强度处理后碳纤维的拉伸强度

Figure 11. Tensile strength of carbon fiber treated with different current intensities

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图 12 不同电流处理后碳纤维的界面剪切强度(IFSS)

Figure 12. Interfacial shear strength (IFSS) of carbon fiber treated with different current intensities

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图 13 碳纤维表面活性官能团与环氧树脂结合机制

Figure 13. Bonding mechanism of active functional groups of carbon fiber surface and epoxy resin

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图 14 用硫酸电解质电化学处理前后碳纤维表面的原子力显微镜图像

Figure 14. Atomic force microscopy images of carbon fiber surfaces before and after electrochemical treatment with sulfuric acid electrolyte

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表 1 碳纤维表面官能团含量

Table 1. Surface functional group contents of carbon fibers

Current intensity /A	Content of functional group/%
Current intensity /A	C=C	C—C	C—OH	C=O	COOH
Untreated 0.0 A	70.33	9.07	6.95	3.72	9.93
H₂SO₄ 0.1 A	68.26	11.80	7.75	5.19	7.01
H₂SO₄ 0.3 A	60.03	14.53	11.21	4.70	9.52
H₂SO₄ 0.5 A	56.31	10.41	16.83	5.72	10.74

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表 2 氧化前后碳纤维的表面粗糙度

Table 2. Surface roughness of carbon fibers before and after oxidation

Surface roughness	Different current intensities of electrochemical oxidation
Surface roughness	Untreated 0 A	H₂SO₄ 0.1 A	H₂SO₄ 0.5 A
R_a/nm	36.4	39.7	41.3
RMS/nm	42.1	46.7	47.7
Notes: R_a—Arithmetic mean of the absolute value of the roughness curve relative to the center line; RMS—Root-mean-square deviation of the roughness curve profile.

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