Preparation and microwave absorption properties of CB/PBO composite

TA salt was prepared by the solution of 4, 6-diaminon1, 3-benzenediol and terephthalic acid, and then copolymerized in PPA to get poly(p-phenylene benzobisoxazole) (PBO) with good thermal resistance. Using as-prepared PBO as matrix, carbon black (CB) as absorber, CB/PBO composites were fabricated by hot pressing. Influences of CB weight concentration on complex permitivity and on thermal properties of CB/PBO composites were investigated. The results show that the real and imaginary parts of permittivity are increased with the increase of carbon black concentration. The reflectivity bandwidth and reflection loss lower than -10 dB are about 2.4 GHz and -32 dB, respectively, when CB weight concentration is 5% and the thickness of composite is 2 mm. The mass loss of PBO and CB/PBO composite are 11.84% and 21.99%, respectively, when kept at 450°C for 5 h.