Lightweight Partition Walls with Embedded Biomass-Based Microwave Absorbers

The development of wireless communication systems has led to electromagnetic (EM) pollution issues, particularly in indoor environments such as offices, hospitals, and houses. To alleviate this issue, this study focuses on the development of light partition walls with incorporated biomass-based microwave absorbers using a composite material comprising 20% palm oil fuel ash (POFA), 10% carbon, and 70% polyurethane (PU) foam. Two gypsum board and cement board structural panels as exterior layers in the same configuration and dimensions were taken to evaluate their individual and combined performance with the absorber mixture. Reflectivity performance of all the prototypes was evaluated using NRL Arch free space method over the wide frequency range of 1 GHz to 12 GHz. Results showed that the gypsum board and cement board, when separately tested in the absence of any absorber layer, did not yield satisfactory absorption, as reflectivity values were all above −10 dB, indicating poor absorption. However, after being coated with the PU foam matrix loaded with the POF A-carbon composite, both configurations exhibited significant improvement. The values of reflectivity for most of the frequency bands were less than −10 dB, which is a testament to the structure's potential to function as an effective microwave absorber. The findings validate the effectiveness of biomass-based fillers in enhancing the electromagnetic absorption effectiveness of conventional partition wall materials. The proposed lightweight alternative not only offers structural strength but also environmental sustainability and enhanced protection against EM exposure, making it suitable for use in modern building structures.