Preparation of macroporous rayon-based activated carbon fiber felt screen/epoxy composites and their microwave absorption properties

摘要

Microwave absorbing materials containing macroporous rayon-based activated carbon fiber (ACF) felt screens were successfully prepared. Microporous ACF felts were firstly marinated in the aqueous solution of NaH2PO4, and then were activated by steam at different temperatures to produce macropores on the surface of ACF. By scanning electron microscopy, we found more macropores generated with the increasing activation temperature, while the resulting macroporous ACF felts possessed larger specific surface areas determined by BET method. Furthermore, ACF felt screens were prepared and then were compounded with epoxy matrix. The microwave absorbing properties of these composites were investigated by vector network analyzer. The results showed that the composites containing the macroporous ACF felts screens rather than microporous ones performed good microwave absorbing properties. Especially for those with ACF felts activated at 750°C, the frequency range, corresponding to the reflection loss below -10dB, covered 9.1 to 18GHz, and the maximum reflection loss achieved -31.5dB. It could be concluded that the specific surface area and the macroporous structure of ACF felts play important roles in the microwave absorption properties of the ACF felt screen/epoxy composites.