再生短碳纤维湿法取向技术及其增强性能分析

李森; 黄海鸿; 刘威豪; 阚峻峰; 刘志峰

doi:10.13801/j.cnki.fhclxb.20210603.001

再生短碳纤维湿法取向技术及其增强性能分析

doi: 10.13801/j.cnki.fhclxb.20210603.001

合肥工业大学　机械工程学院，合肥 230009

基金项目: 国家自然科学基金优秀青年基金项目(51722502)；国家自然科学基金面上项目(51775162)

详细信息

通讯作者:
黄海鸿，博士，教授，博士生导师，研究方向为绿色制造、再制造与回收再资源化等　E-mail：huanghaihong@hfut.edu.cn

中图分类号: TB332
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出版历程
- 收稿日期: 2021-03-25
- 修回日期: 2021-05-12
- 录用日期: 2021-05-21
- 网络出版日期: 2021-06-04
- 刊出日期: 2021-03-01

Wet orientation technology of recycled short carbon fiber and analysis of its reinforcement performance

School of Mechanical Engineering, Hefei University of Technology, Hefei 230009, China

摘要

摘要: 碳纤维/环氧树脂(CF/EP)复合材料具有力学性能优异、质量轻、耐腐蚀等特点，但成本高、废弃物环境影响大等问题制约了其进一步应用。现有方法回收的再生碳纤维(RCF)多为蓬松状的短纤维束，纤维互相缠绕，其优异的力学性能难以得到充分的利用。采用湿法纤维取向技术对不同长度的RCF进行重新取向排布，得到了相应的取向纤维毡，并用模压法制备了RCF/EP复合材料试样。利用二维方向张量对RCF的取向度(D_PA)进行评价，采用SEM和力学性能测试表征复合材料的结构与性能。结果表明，RCF长度越长，取向越困难；RCF长度和D_PA的增加使复合材料的力学性能得到提高；与2 mm RCF相比，6 mm RCF的D_PA降低了约11%，而RCF/EP的拉伸强度和模量、弯曲强度和模量分别提升了63.6%、91.5%、48.8%、43.0%。
- 纤维取向 /
- 短碳纤维 /
- 碳纤维增强树脂复合材料 /
- 回收再利用 /
- 力学性能
Abstract: Despite carbon fiber/epoxy (CF/EP) composites have the characteristics of excellent mechanical properties, light weight and corrosion resistance, problems such as high cost and severe environmental impact of waste restrict their further applications. Most of the recycled carbon fibers (RCF) recovered by the existing methods are fluffy, short and entangled with each other, which limit its mechanical properties. To address this issue, a wet fiber orientation technology was proposed to reorient and arrange RCF with different lengths. An oriented fiber felt was obtained via this method and RCF/EP fabricate specimens were prepared by compression moulding. The orientation tensor in the 2D plane was applied to evaluate the preferential alignment degree (D_PA) of the fiber. The microstructure and properties of the composites were analyzed by SEM and mechanical tests, respectively. The results show that the increasing of RCF length leads to poor fiber orientation. The mechanical properties of the composites are improved with the increase of RCF length and D_PA. Compared with 2 mm RCF, the D_PA of 6 mm RCF decreases by about 11%, whereas the tensile strength and modulus, flexural strength and modulus of the reinforced resin matrix composites increase by 63.6%, 91.5%, 48.8% and 43.0%, respectively.
- fiber orientation /
- short carbon fiber /
- carbon fiber reinforced polymer /
- recycling and reuse /
- mecha-nical properties

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图 1 湿法短切碳纤维连续取向装置示意图

Figure 1. Schematic diagram of the continuous orientation device for wet shortening carbon fibers

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图 2 纤维的主方向向量${\boldsymbol{P}} $定义图解

Figure 2. Definition of the main direction vector ${\boldsymbol{P}} $ of the fiber

${\boldsymbol{P}} $—Orientation vector of carbon fiber; P_i, P_j—Components of the orientation vector in y, x; α—Orientation angle of carbon fiber.

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图 3 2 mm RCF毡的微观图、二阶方向张量和取向椭圆

Figure 3. Microscopic images, orientation tensors in the 2D plane and the ellipses of 2 mm RCF felts

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图 4 2 mm RCF/EP复合材料与纯环氧树脂的力学性能

Figure 4. Mechanical properties of 2 mm RCF/EP composites and pure epoxy resin

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图 5 4 mm与6 mm RCF毡微观图像、二阶方向张量及取向椭圆

Figure 5. Microscopic images, orientation tensors in the 2D plane and ellipses of the 4 mm and 6 mm RCF felts

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图 6 RCF/EP复合材料与纯环氧树脂的力学性能

Figure 6. Mechanical properties of RCF/EP composites and pure epoxy resin

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图 7 CF/EP复合材料与纯环氧树脂的力学性能

Figure 7. Mechanical properties of CF/EP composites and pure epoxy resin

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图 8 URCF/EP复合材料SEM图像：(a)断裂面；(b)与(a)断裂面垂直

Figure 8. SEM images of URCF/EP composite: (a) Fracture surface; (b) Perpendicular to fracture (a)

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图 9 ORCF/EP复合材料断裂面SEM图像：(a)与取向方向平行；(b)与取向方向垂直

Figure 9. SEM images of ORCF/EP composite fracture surfaces: (a) Parallel to the orientation; (b) Perpendicular to the orientation

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表 1 实验方案

Table 1. Experimental schemes

No.	Scheme	Abbreviation
1	2 mm Unoriented recycled carbon fiber	2URCF
2	2 mm Oriented recycled carbon fiber	2ORCF
3	2 mm Oriented virgin carbon fiber	2OVCF
4	4 mm Oriented recycled carbon fiber	4ORCF
5	6 mm Unoriented recycled carbon fiber	6URCF
6	6 mm Oriented recycled carbon fiber	6ORCF
7	6 mm Oriented virgin carbon fiber	6OVCF
8	Pure epoxy resin	EP

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表 2 碳纤维/环氧树脂 (CF/EP)复合材料中各参数的实测值及单项误差

Table 2. Measured values of parameters and the errors of carbon fiber/epoxy (CF/EP) composites

Component	Parameter	Measured value	Single error
RCF	ρ₁/(g·cm⁻³)	1.78	0.01
RCF	w₁/wt%	11.5	0.5
EP	ρ₂/(g·cm⁻³)	1.12	0.02
EP	w₂/wt%	85.5	0.5
HEC	ρ₃/(g·cm⁻³)	0.75	0.01
HEC	w₃/wt%	3.0	0.5
CF/EP composite	ρ/(g·cm⁻³)	1.12	0.01
Notes: RCF—Recycled carbon fiber; HEC—Hydroxyethyl cellulose; ρ—Density; w—Weight fraction.

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表 3 2 mm RCF不同实验组的纤维取向度D_PA

Table 3. Preferential alignment degree D_PA of 2 mm RCF under various experimental conditions

Group	Long axes of the ellipse m	Short axes of the ellipse n	Included angle θ/(°)	D_PA/%
2URCF	0.691	0.309	135.8	38.1
2ORCF*	0.842	0.158	9.9	68.4
2ORCF(90°)	0.945	0.055	165.5	89.0
2ORCF	0.983	0.017	11.7	96.5

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表 4 不同长度RCF实验组的D_PA

Table 4. D_PA of different length RCF groups

Group	Long axes of the ellipse m	Short axes of the ellipse n	Included angle θ/(°)	D_PA/%
2ORCF	0.983	0.017	11.7	96.5
4ORCF	0.961	0.039	4.2	91.9
6ORCF	0.924	0.076	10.4	84.9

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表 5 RCF与VCF实验组的D_PA

Table 5. D_PA of the RCF and VCF experimental groups

Group	Long axes of the ellipse m	Short axes of the ellipse n	Included angle θ/(°)	D_PA/%
2ORCF	0.983	0.017	11.7	96.5
2OVCF	0.986	0.014	10.4	97.2
6ORCF	0.924	0.076	10.4	84.7
6OVCF	0.921	0.079	11.4	84.2

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