工业用环氧树脂及其复合材料的闭环回收再制造

安乐; 赵文哲; 金宸宇

doi:10.13801/j.cnki.fhclxb.20220822.002

工业用环氧树脂及其复合材料的闭环回收再制造

doi: 10.13801/j.cnki.fhclxb.20220822.002

西安交通大学　航天航空学院，西安 710049

基金项目: 国家重点研发计划 (2019YFA0706800)；中国博士后基金面上项目(2019M663676)；中央高校基础科研业务费(xjh012019035)

详细信息

通讯作者:
安乐，博士，助理教授，研究方向为复合材料连接、回收及其力学　E-mail: anle2018@mail.xjtu.edu.cn

中图分类号: X705；V258
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- 被引次数: 0
出版历程
- 收稿日期: 2022-05-13
- 修回日期: 2022-07-30
- 录用日期: 2022-08-06
- 网络出版日期: 2022-08-23
- 刊出日期: 2023-05-15

Closed-loop recycling and re-manufacturing of engineering epoxy and its composites

School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China

Funds: National Key R&D Program of China (2019YFA0706800); China Postdoctoral Science Foundation (2019M663676); Fundamental Research Funds for the Central Universities (xjh012019035)

摘要

摘要: 环氧树脂基碳纤维增强复合材料因其优异的力学、热学性能已广泛应用于航天航空等领域。环氧树脂由三维共价交联网络组成，难以被降解。工业中通常需高温(300~800℃)、高压(3~27 MPa)等严苛环境或有毒催化剂来破坏树脂基体，以回收复合材料废弃物中昂贵的碳纤维，这一过程往往会造成纤维性能的严重损失。本文利用环氧树脂与醇溶剂之间的动态键交换反应，将工业中常用的高性能环氧树脂降解为低聚物，降解条件温和(200℃、0 MPa)，且无需额外催化剂。通过树脂降解，回收得到结构完整的碳纤维织物，其强度保持在94%以上，可继续用于制备复合材料。将低聚物作为反应物制备新的环氧树脂，称为再制造环氧树脂。当再制造环氧树脂中低聚物的含量为20wt%时，其强度与原环氧树脂相当，而断裂伸长率提高了20%。用再制造环氧树脂制备碳纤维复合材料，其强度与原环氧基复合材料相当，同时断裂伸长率提高了50%。本文实现了工业用环氧树脂及其复合材料从制造到回收到再制造过程，即闭环回收再制造。同时，本文新提出了一种绿色、简单、有效的环氧树脂增韧方法。
- 环氧树脂 /
- 复合材料 /
- 键交换 /
- 回收再制造 /
- 增韧
Abstract: High-performance carbon fiber reinforced epoxy composites have become important materials for aircraft manufacturing due to their excellent mechanical and thermal properties. The three-dimensional crosslinked network of epoxy matrix is insoluble, making degrading and recycling challenging. In engineering, to reclaim the expensive carbon fiber from composite wastes, harsh conditions such as high temperature (300-800℃), high pressure (3-27 MPa), and trenchant catalyst are usually demanded to destroy the epoxy matrix. However, the properties of carbon fibers are deteriorated simultaneously. In this work, high-performance epoxy resin was decomposed into oligomers via the bond exchange reactions between the epoxy and alcohol solvent. The epoxy resin was dissolved in the alcohol solvent at mild condition (200℃, 0 MPa). Meanwhile, the woven structure of the recycled fabric remains intact, and its tensile strength is 94% of the fresh fabric. Thereby, the recycled fabrics can be used to prepare new composites. Furthermore, the decomposed epoxy oligomer (DEO) is used as a reactant to prepare new epoxy resin. When the DEO content is 20wt%, the elongation at break of the new resin is significantly improved by 20%, while its strength is similar to the original epoxy resin. For the same DEO content, the elongation at break of re-manufactured epoxy composites increased by 50%, compared to the fresh one. To sum up, we develop a closed-loop recycling and re-manufacturing method for an epoxy resin and its composite, and a novel method for the toughening of epoxy resin that is eco-friendly, easy and efficient.
- epoxy /
- composite /
- bond exchange reaction /
- recycling and re-manufacturing /
- toughening

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图 1 环氧树脂的闭环回收再制造过程

DGEBA—Diglycidyl ether of bisphenol A; GA—Glutaric anhydride; DMP-30—2, 4, 6-tris(dimethylaminomethyl)phenol; EG—Ethylene glycol

Figure 1. Closed-loop recycling and re-manufacturing of the epoxy resin

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图 2 环氧基复合材料的闭环回收再制造过程

DEO—Decomposed epoxy oligomer; CF—Carbon fiber; CFRP—Carbon fiber reinforced polymer

Figure 2. Closed-loop recycling and re-manufacturing of the epoxy composite

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图 3 不同DEO含量的再制造环氧树脂的DSC曲线

Figure 3. DSC curves of the re-manufactured epoxy resins with different DEO contents

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图 4 不同DEO含量的再制造环氧树脂的FTIR结果

δ—Characteristic absorption peak; ν—Stretching vibration peak

Figure 4. FTIR results of re-manufactured epoxy resins with different DEO contents

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图 5 不同DEO含量的再制造环氧树脂的DMA测试结果

Figure 5. DMA results of re-manufactured epoxy resins with different DEO contents

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图 6 再制造环氧树脂的单轴拉伸应力-应变曲线

Figure 6. Uniaxial tensile stress-strain curves of re-manufactured epoxy resins

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图 7 再制造环氧树脂的热失重分析

Figure 7. TGA results of re-manufactured epoxy resins

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图 8 回收环氧基复合材料的单轴拉伸应力-应变曲线

Figure 8. Uniaxial tensile stress-strain curves of re-manufactured epoxy composites

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图 9 原始碳纤维织物 (a) 与回收碳纤维织物 (b) 的SEM图像

Figure 9. SEM images of the original (a) and recycled (b) fiber fabrics

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图 10 原始碳纤维织物(CFs)和回收碳纤维织物(RCFs)的TGA曲线

Figure 10. TGA curves of original carbon fiber fabric (CFs) and recycled carbon fiber fabric (RCFs)

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图 11 原始碳纤维织物(CFs)和回收碳纤维织物(RCFs)的单轴拉伸力学性能

Figure 11. Uniaxial tensile mechanical properties of original carbon fiber fabrics (CFs) and recycled carbon fiber fabrics (RCFs)

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图 12 CFs/epoxy复合材料和RCFs/epoxy复合材料的单轴拉伸应力-应变曲线

Figure 12. Uniaxial tensile stress-strain curves of CFs/epoxy and RCFs/epoxy composites

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表 1 再制造环氧树脂及其复合材料的命名

Table 1. Naming of re-manufactured epoxy resins and composites

Material	DEO content/wt%
Epoxy	0
REP10	10
REP20	20
REP30	30
REP50	50
CFs/epoxy	0
CFs/REP10	10
CFs/REP20	20
CFs/REP30	30
CFs/REP50	50
Notes: REP—Re-manufactured epoxy resins; CFs—Carbon fiber; DEO—Decomposed epoxy oligomer.

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表 2 再制造环氧树脂的单轴拉伸力学性能

Table 2. Uniaxial tensile mechanical properties of re-manufactured epoxy resins

Material	DEO/wt%	Tensile strength/MPa	Elastic modulus/MPa	Elongation at break/%
Epoxy	0	74.7±1.4	1875.7±31.5	4.8±0.1
REP10	10	76.4±3.6	1935.1±34.0	5.5±0.2
REP20	20	74.3±1.2	1876.8±35.1	5.7±0.2
REP30	30	72.7±2.1	1756.9±48.7	5.9±0.1
REP50	50	17.2±1.7	429.5±9.2	130.4±19.9

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表 3 再制造环氧树脂的热失重分析结果

Table 3. TGA results of re-manufactured epoxy resins

Material	DEO/wt%	T_5%/°C	T_10%/°C	T_max/°C
Epoxy	0	384	399	427
REP10	10	379	396	426
REP20	20	381	397	427
REP30	30	381	397	427
REP50	50	357	387	426
Notes: T_5%—Temperature at 5wt% mass loss; T_10%—Temperature at 10wt% mass loss; T_max—Temperature corresponding to the maximum mass lose rate.

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表 4 回收环氧基复合材料的单轴拉伸力学性能

Table 4. Uniaxial tensile mechanical properties of re-manufactured epoxy composites

Material	DEO/wt%	Tensile strength/MPa	Elastic modulus/GPa	Elongation at break/%
CFs/epoxy	0	647.9±9.8	20.5±1.6	6.5±0.8
CFs/REP10	10	737.5±17.8	21.9±2.4	7.6±0.6
CFs/REP20	20	651.9±9.3	18.2±3.7	7.7±2.3
CFs/REP30	30	572.6±38.9	15.0±2.5	8.2±2.6
CFs/REP50	50	402.2±38.9	11.9±1.4	11.0±0.8

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