Zheng Liu, Xiaoli Fan, Junliang Zhang*, Zhiyong Yang, Yusheng Tang, Jianwei Li, Jie Kong and Junwei Gu*. Improving the comprehensive properties of PBO fibres/cyanate ester composites using a hyperbranched fluorine and epoxy containing PBO precursor. Composites Part A: Applied Science and Manufacturing, 2021, 150: 106596. 2020IF=7.664.（1区材料科学Top期刊）

（https://doi.org/10.1016/j.compositesa.2021.106596）

Abstract

Hyperbranched fluorine and epoxy containing PBO precursor (epoxy-preFHBPBO) was synthesized and utilized as interface compatibilizer to synchronously improve the mechanical and dielectric properties of poly(p-phenylene-2, 6-benzobisoxazole) (PBO) fibres reinforced bisphenol A dicyanate ester (BADCy) resins (PBO fibres/FHBPBO-co-BADCy) laminated composites. ¹H NMR, ¹³C NMR, and FTIR analyses confirmed the successful preparation of epoxy-preFHBPBO. The introduction of hyperbranched structure and fluorine groups significantly improved the mechanical properties and wave-transparent performance. Compared with PBO fibres/BADCy, the flexural strength and interlaminar shear strength of PBO fibres/FHBPBO-co-BADCy composites with 7 wt.% epoxy-preFHBPBO were respectively enhanced to 634.9 and 46.9 MPa, increased by 8.1% and 27.8%. The corresponding dielectric constant and dielectric loss were 2.65 and 0.003, respectively, lower than those of PBO fibres/BADCy (3.06 and 0.006) composites. Meanwhile, the corresponding volume resistivity and breakdown strength were 4.93×10¹⁵ Ω?cm and 25.38 kV/mm, higher than PBO fibres/BADCy resins composites (2.2×10¹⁵ Ω?cm and 17.69 kV/mm).

以缩聚和端基修饰制备得到的环氧端基含氟超支化PBO前驱体（epoxy-preFHBPBO）为界面相容剂，经高温模压制备PBO纤维/FHBPBO-co-BADCy层压透波复合材料。FTIR、¹H NMR和¹³C NMR证明成功制备出具有预期分子结构的epoxy-preFHBPBO。超支化拓扑结构和含氟基团的引入能够显著改善BADCy树脂的力学性能和介电性能。当epoxy-preFHBPBO的用量为7 wt%时，PBO纤维/FHBPBO-co-BADCy层压透波复合材料的弯曲强度和层间剪切强度分别从PBO纤维/BADCy的587.4 MPa和36.7 MPa提升至634.9 MPa和46.9 MPa，分别提升了8.1%和27.8%；1 MHz下PBO纤维/FHBPBO-co-BADCy的介电常数和介电损耗角正切值分别为2.65和0.003，低于PBO纤维/BADCy层压透波复合材料的ε和tanδ（3.06和0.006）。PBO纤维/FHBPBO-co-BADCy层压透波复合材料的体积电阻率和击穿电压值分别为4.93×10¹⁵ Ω?cm和25.38 kV/mm，高于PBO纤维/BADCy层压透波复合材料（2.2×10¹⁵ Ω?cm and 17.69 kV/mm）。

论文创新点

1. 环氧端基含氟超支化PBO前驱体（epoxy-preFHBPBO）的引入能够显著改善BADCy树脂的力学性能、介电性能及与PBO纤维之间的界面相容性。
2. PBO纤维/FHBPBO-co-BADCy层压透波复合材料的弯曲强度和ILSS分别从PBO纤维/BADCy的587.4 MPa和36.7 MPa提升至634.9 MPa和46.9 MPa。1 MHz下的ε和tanδ分别为2.65和0.003，均低于PBO纤维/BADCy的ε和tanδ（3.06和0.006）。
3. 基于传输/反射法建立的仿真透波模型表明PBO纤维/FHBPBO-co-BADCy层压复合材料在不同厚度（1~5 mm）下均具有优异的透波性能。