Polyimide nanofiber self-reinforced film with high transparency and low thermal expansion coefficient
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摘要: 应用于柔性显示的聚酰亚胺(Polyimide,PI)膜要求高透明性和低热膨胀系数CTE,而目前高透明聚酰亚胺的CTE普遍高于40×10−6/℃。本研究采用同质增强法,将高强度的纳米PI纤维与无色透明热塑性含氟聚酰亚胺(PI-F)复合,得到的纳米PI纤维增强PI-F基复合薄膜不仅保持PI-F的高透明,同时具有更低的CTE和优异的拉伸性能。研究结果表明:纳米尺寸的纤维可减少光透过时发生的散射,使复合薄膜维持了较高的透明性。当纳米PI纤维质量分数为10%时,在可见光区其透光率达到80.5%,与纯PI-F薄膜相比,复合薄膜的CTE值降低了40.3%,为28.3×10−6/℃。其拉伸强度提高了132.9%,达到107.6 MPa,拉伸模量增大了89.5%,达到1152.2 MPa。Abstract: The colorless polyimide (PI) used for the flexible display field is required to have high transparency and low thermal expansion coefficient CTE. However, the CTE value of commercial colorless PI film is above 40×10−6/℃. In the study, nanofiber self-filled PI film was prepared by embedding the PI nanofiber-net in thermoplastic fluorinated polyimide solution (PI-F). The nanofiber-net self-filled PI film demonstrates high transparency retention, much CTE and excellent tensile property. The results show that the fiber of nanosize avoids light scattering, therefore the high transparency of the film is retained. When the PI fiber mass fraction is 10%, the transparency of the film is 80.5%. In comparison to the pure PI-F film, the CTE of composite film is reduced by 40.3% and reaches 28.3×10−6/℃; The tensile strength and the tensile modulus of the composite film are increased by 132.9% and 89.5%, respectively and are 107.6 MPa and 1152.2 MPa correspondingly.
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Key words:
- polyimide /
- nanofibers /
- micro-structure /
- self enhancement /
- thermal expansion coefficient
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图 7 纳米PI纤维及其增强PI-F基复合薄膜的XRD图谱 (a);纳米PI纤维的SEM图像 (b);纳米PI纤维增强PI-F基复合薄膜横截面图 ((c)~(f)) (纤维含量: (d) 5%; (e) 10%; (f) 15%)
Figure 7. XRD spectra of PI nanofibers and PI nanofibers filled PI-F films (a); SEM image of PI nanofibers (b); SEM images of the cross-section morphology of PI nanofibers filled PI-F films ((c)-(f)) (Fiber content: (d) 5%; (e) 10%; (f) 15%)
表 1 纳米PI纤维增强PI-F基复合薄膜的组分质量含量(干膜)
Table 1. Composition of the PI nanofiber filled PI-F films (mass ratio based on dry film)
Sample PI nanofibers/% PI-F/% Pure PI-F film 0 100 5% PI nanofibers filled film 5 95 10% PI nanofibers filled film 10 90 15% PI nanofibers filled film 15 85 表 2 纳米PI纤维增强PI-F基复合薄膜的热膨胀系数CTE值及拉伸性能
Table 2. Thermal expansion coefficient CTE and tensile properties of PI nanofibers filled PI-F films
Sample CTE/(10−6℃−1) Tensile modulus/MPa Elongation at break/% Tensile strength/MPa Pure PI-F film 47.2 608.1±3.7 26.3±0.1 46.2±7.6 5% PI nanofibers filled film 34.4 987.0±1.9 18.6±0.1 73.8±5.7 10% PI nanofibers filled film 28.3 1152.2±2.5 15.9±0.1 107.6±6.5 15% PI nanofibers filled film 27.2 1388.9±3.2 15.2±0.1 122.4±7.1 -
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