同质纳米纤维增强制备透明低膨胀系数聚酰亚胺

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C_TE，而目前高透明聚酰亚胺的C_TE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C_TE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C_TE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。 

Polyimide nanofiber self-reinforced film with high transparency and low thermal expansion coefficient

The colorless polyimide (PI) used for the flexible display field is required to have high transparency and low thermal expansion coefficient C_TE. However, the C_TE 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 C_TE 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 C_TE 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.