Preparation of poly-p-phenylenebenzobisoxazole (PBO) fibrillated pulp and dielectric properties of carbon fiber/PBO wet-laid nonwoven fabric

A method to prepare a kind of wet-laid nonwoven fabric that can be used in microwave absorbing honeycomb is proposed. It was prepared through a papermaking process with carbon fiber (CF) and poly-p-phenylenebenzobisoxazole (PBO) fibrillated pulp. Fibrillated PBO pulp has a large surface area and lots of micro-fibrils which is beneficial for the uniformity and mechanical strength of the wet-laid nonwoven fabric. The electromagnetic properties and absorbing performances of the wet-laid nonwoven fabric with different content of CF were compared. The results showed that the complex permittivity increased when the content of the CF increased, and then decreased when the content was higher than 10 wt%. The resistivity measured by four probe testers decreased with the increase of the content of CF. Calculated by the measured complex permittivity and permeability, the CF/PBO wet-laid nonwoven fabric had a lowest reflection loss of -27.60 dB at a content of 20 wt%, with an optimum thickness of 1.72 mm.