碳纤维增强含酯键环氧树脂基复合材料的化学降解与回收

张洋; 张隽爽; 马崇攀; 孙忠霄; 王宇

doi:10.13801/j.cnki.fhclxb.20221111.001

碳纤维增强含酯键环氧树脂基复合材料的化学降解与回收

doi: 10.13801/j.cnki.fhclxb.20221111.001

张洋^1,,
张隽爽¹,
马崇攀¹,
孙忠霄¹,
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

基金项目: 国家自然科学基金(52102033)；装备预研教育部联合基金(6141 A02033231)National Natural Science Foundation of China (52102033); Joint Fund of Ministry of Education for Equipment Research (6141 A02033231)

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: TQ342.31；TB332
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- 文章访问数: 1024
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- 被引次数: 0
出版历程
- 收稿日期: 2022-10-05
- 修回日期: 2022-10-29
- 录用日期: 2022-11-06
- 网络出版日期: 2022-11-14
- 刊出日期: 2023-09-15

Chemical degradation and recovery of carbon fiber reinforced epoxy resin matrix composites containing ester bond

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

摘要

摘要: 随着环氧树脂基碳纤维复合材料的广泛应用，其废旧产品的回收成为低碳发展的重要问题。采用GC-MS、FTIR、XPS、SEM等表征方法研究了含酯键的环氧树脂基碳纤维复合材料的树脂降解机制及降解过程对回收碳纤维结构和性能的影响。研究结果表明：在苯甲醇用量120 mL、质量比W(NaOH)∶W(ZnCl₂)=1∶1和降解温度190℃的前提下，最佳降解时间为1 h，较优的降解配方为NaOH和树脂均为1 g。降解得到的产物静置分层，上层清液的苯甲醇含量达99%；环氧树脂的降解机制为苯甲醇在碱性环境下电离生成苄氧基，苄氧基进攻环氧树脂中的酯键，发生酯交换反应，使酯键断裂实现降解，生成苯甲醇酯及醇阴离子，苯甲醇酯在碱性环境下发生皂化反应重新生成苯甲醇，酯交换反应和皂化反应重复进行，直至最终降解完成；回收碳纤维与原始碳纤维的表面O/C、表面光洁程度均在一个水平，回收碳纤维的强度保留率达97%。
- 碳纤维复合材料 /
- 降解回收 /
- 含酯键的环氧树脂 /
- 循环利用 /
- 碱性环境
Abstract: With the wide application of epoxy resin-based carbon fiber composites, the recycling of their waste products had become an important issue for low-carbon development. The resin degradation mechanism of epoxy resin-based carbon fiber composites containing ester bonds and the effect of degradation process on the structure and properties of recycled carbon fibers were studied by GC-MS, FTIR, XPS, SEM and other characterization methods. The results show that the optimal degradation time is 1 h under the conditions of benzyl alcohol dosage of 120 mL, mass ratio W (NaOH)∶W (ZnCl₂)=1∶1 and degradation temperature of 190℃, and the optimal dosages of NaOH and resin are both 1 g. The degradation products are separated by standing stratification, and the content of benzyl alcohol in the supernatant is 99%. The degradation mechanism of the resin is as follows: Firstly, benzyl alcohol is ionized to generate benzyloxy group in an alkaline environment, and the benzyloxy groups attack ester bonds in the resin, and transesterification reaction occures to break the ester bond to achieve degradation. Benzyl alcohol ester and alcohol anion are produced by transesterification reaction. Next, the benzyl alcohol ester undergoes saponification reaction in alkaline environment to regenerate benzyl alcohol. The transesterification reaction and the saponification reaction are repeated until the final degradation is completed. The surface O/C and surface smoothness of the recycled carbon fibers and the original carbon fibers are at the same level, and the strength retention rate of the recycled carbon fibers reaches 97%.
- carbon fiber composites /
- chemical degradation /
- epoxy resin containing ester bond /
- recycling /
- alkaline environment

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图 1 降解时间对环氧树脂基体降解率的影响

Figure 1. Effect of degradation time on degradation rate of epoxy resin matrix

Benzyl alcohol 120 mL, mass ratio W(NaOH)∶ W(ZnCl₂)=1∶1, NaOH 1 g, ZnCl₂ 1 g, composite materials 2 g

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图 2 NaOH加入量对环氧树脂基体降解率的影响

Figure 2. Effect of NaOH dosage on degradation rate of epoxy resin matrix

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图 3 回收所得上清液与纯苯甲醇的FTIR图谱

Figure 3. FTIR spectra of recovered supernatant and pure benzyl alcohol

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图 4 降解后溶液下层的胶状产物的液质联用测试结果: (a) 正离子；(b) 负离子

Figure 4. Results of LC-MS of degraded and recovered colloid: (a) Positive ion; (b) Negative ion

m/z—Mass-to-charge ratio

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图 5 降解回收胶体与纯环氧树脂的FTIR图谱

Figure 5. FTIR spectra of degraded and recovered colloid and pure epoxy resin

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图 6 环氧树脂基体降解过程机制图

Figure 6. Schematic diagram of degradation process of epoxy resin matrix

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图 7 原始碳纤维和降解回收碳纤维的表面形貌对比图

Figure 7. Comparison diagram of surface morphology of original carbon fiber and degraded carbon fiber

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表 1 碳纤维复合材料环氧树脂降解后所得碳纤维力学性能和表面理化结构与原始碳纤维对比表

Sample	Tensile strength of monofilament/GPa	Element content			surface morphology
Sample	Tensile strength of monofilament/GPa	C/%	O/%	C/O	surface morphology
Initial carbon fibers	3.44±0.08	84.65	13.26	0.157
Recycled carbon fibers	3.34±0.10	84.51	13.36	0.158

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表 1 碳纤维复合材料降解1 h后上清液的GC-MS结果

Table 1. GC-MS results of supernatant after 1 h degradation of carbon fiber composite

Sequence number	Retention time/min	Components’ name	Molecular structure	Content mol/%
1	8.460	Benzaldehyde		0.101
2	9.842	Benzyl alcohol		99.878
Others				0.021

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表 2 降解前后碳纤维表面的元素含量

Table 2. Element content of carbon fiber surface before and after degradation

Sample	Degradation rate/%	C/%	O/%	C/O
Initial carbon fibers	–	84.65	13.26	0.157
Recycled carbon fibers (W(NaOH)：W(Resin)=1∶1)	100	84.51	13.36	0.158
Recycled carbon fibers (W(NaOH)：W(Resin)=0.1∶1)	75.7	80.40	17.34	0.216

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表 3 原始碳纤维和降解回收碳纤维的单丝拉伸强度对比

Table 3. Comparison of tensile strength of carbon fiber monofilament before and after degradation

Sample	Degradation rate/%	Tensile strength of monofilament/GPa
Initial carbon fibers	–	3.44±0.08
Recycled carbon fibers (W(NaOH)∶W(Resin)=1∶1)	100	3.34±0.10

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