Effect of carbon nanotubes on interfacial properties of a carbon fiber / polycarbonate composite
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摘要: 为改善炭纤维和聚碳酸酯界面结合性能,制备了含碳纳米管的水性聚碳酸酯上浆剂和水性聚氨酯上浆剂,通过上浆工艺将碳纳米管引至炭纤维表面。分别采用单丝段裂法和定向纤维增强聚合物基复合材料垂直方向拉伸两种方法从微观和宏观两个角度研究了上浆剂种类及碳纳米管含量对复合材料界面结合性能的影响。结果表明:上浆剂可明显改善炭纤维/聚碳酸酯复合材料界面结合性能,由于优异的成膜性,聚氨酯上浆剂改善效果更明显;碳纳米管的加入对复合材料的界面性能有一定改善,在微观评价方法中,碳纳米管改善效果显著,因为碳纳米管可有效阻止界面滑移;在宏观评价中,碳纳米管改善效果不明显,主要是上浆剂的界面黏结发挥作用。Abstract: In order to improve interfacial bonding between carbon fiber (CF) and polycarbonate (PC), sizing agents of water-borne polycarbonate (WPC) and water-borne polyurethane (WPU) containing carbon nanotubes (CNTs) were used to treat the CFs. CNTs were introduced onto the surfaces of the CFs by a sizing process. The effects of sizing agents and CNT content on the interfacial properties of the composites were investigated by two methods, a single fiber fragmentation test (SFFT) for the monofilament reinforced composite and a transverse tensile test for the directional bundle composite. The results show that WPU is more conducive to improving the interfacial bonding properties of CF/PC composites because of its film-forming property, and the addition of CNTs has a beneficial effect on the interfacial properties of the composites. CNTs can effectively prevent interfacial slip and therefore significantly improve the interfacial properties in the SFFT, while the improvement is not obvious in a transverse tensile test because the adhesion of sizing agents plays a leading role.
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Key words:
- Carbon nanotubes /
- Sizing agent /
- Carbon fiber /
- Polycarbonate /
- Interface
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图 4 SEM照片:(a) 未上浆炭纤维CF;(b~f) PU上浆剂处理纤维,依次为CF0,CF0.05,CF0.1,CF0.2,CF0.3;(g~j) PC上浆剂处理纤维,依次为CF0,CF0.05,CF0.1,CF0.2
Figure 4. SEM images of CFs: (a) CF;(b–f) Fibers treated with PU sizing agent, from left to right,CF0,CF0.05,CF0.1,CF0.2,CF0.3;(g–j) PC sizing agent, from left to right,CF0,CF0.05,CF0.1,CF0.2.
图 6 临界饱和状态双折射现象: (a) CF;(b) CF0(WPU);(c) CF0(WPC);(d) CF0.1(WPU);(e) CF0.1(WPC)及断点示意图: (f) 较弱结合;(g) 较强结合
Figure 6. Birefringence patterns obtained at the saturation state: (a) CF;(b) CF0(WPU); (c) CF0(WPC); (d) CF0.1(WPU); (e) CF0.1(WPC) and the model diagram of breakpoint morphology: (f) weaker combination, (g) stronger combination.
表 1 上浆剂处理前后炭纤维表面官能团种类及含量
Table 1. The species and contents of functional groups on carbon fiber before and after sizing.
Functional group
(Bind energy (eV))CF WPU WPC C=C, C―C (284.4–284.8) 80.79 48.47 76.18 C―O (286.1–286.5) 15.32 36.30 11.86 C=O (287.4–288.0) 3.89 10.21 - O―C=O (288.4–288.9) - 5.02 8.85 O―C(O)―O (290.4–290.8) - - 3.11 表 2 通过原子力显微镜测得炭纤维表面粗糙度Ra (nm)
Table 2. The surface roughness of CFs via AFM Ra (nm).
CNT (wt%) As-received CF 0 0.05 0.1 0.2 0.3 WPU 39.42 33.25 89.25 102.35 125.68 498.32 WPC 32.96 93.65 121.37 136.98 632.69 表 3 CF单丝拉伸性能及Weibull模量
Table 3. Tensile properties and Weibull modulus.
CF WPU WPC σf / GPa m σf / GPa m CF 2.55 ± 0.52 6.069 2.55 ± 0.52 6.069 CF0 2.79 ± 0.43 6.542 2.77 ± 0.56 6.057 CF0.05 2.71 ± 0.56 6.150 2.69 ± 0.60 6.946 CF0.1 2.73 ± 0.50 6.881 2.70 ± 0.48 6.767 CF0.2 2.73 ± 0.52 6.989 2.72 ± 0.55 7.632 表 4 DCAT-21测量不同炭纤维在测试液体动态接触角(单位:°)
Table 4. Dynamic contact angle of carbon fibers with two different test liquids via DCAT-21 (Unit is degree).
CF WPU WPC Water DIM Water DIM CF 75.32 ± 0.24 40.30 ± 0.18 75.32 ± 0.24 36.60 ± 0.18 CF0 63.38 ± 0.16 40.81 ± 0.15 63.98 ± 0.15 40.35 ± 0.10 CF0.05 64.29 ± 0.19 36.45 ± 0.16 64.32 ± 0.19 36.42 ± 0.15 CF0.1 64.67 ± 0.19 36.38 ± 0.15 64.75 ± 0.21 36.29 ± 0.13 CF0.2 65.07 ± 0.23 36.35 ± 0.16 65.04 ± 0.19 36.29 ± 0.20 表 5 定向CF/PC复合材料垂直拉伸结果
Table 5. The results of vertical direction stretching for CF/PC composite.
CF WPU WPC σt/MPa Increase/% Et/GPa σt/MPa Increase/% Et/GPa CF 49.02 ± 2.67 - 1.79 ± 0.09 49.02 ± 2.67 - 1.79 ± 0.09 CF0 57.65 ± 2.08 17.61 1.88 ± 0.05 57.77 ± 2.11 17.85 2.14 ± 0.06 CF0.05 58.40 ± 1.89 19.14 1.96 ± 0.08 58.02 ± 2.55 18.36 1.72 ± 0.09 CF0.1 59.56 ± 2.60 21.50 1.78 ± 0.09 58.40 ± 2.86 19.13 1.61 ± 0.09 CF0.2 55.51 ± 2.92 13.24 1.52 ± 0.08 54.60 ± 1.25 11.38 1.49 ± 0.09 CF0.3 46.52 ± 2.35 −5.10 1.51 ± 0.05 44.10 ± 2.27 −10.04 1.57 ± 0.06 -
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