Tuning the Morphology of Immiscible Polymer Blend-Based Hybrid Nanocomposite for Improving Microwave Absorption Response

Polymer-blend-based nanocomposites incorporating carbon nanomaterials hold significant potential for microwave absorption materials (MAM) applications. This study investigates the microwave absorption response of hybrid nanocomposites composed of multiwalled carbon nanotubes (MWCNT) and nanographite, prepared using industrial-like melt-mixing masterbatch strategies in a polycarbonate/acrylonitrile-butadiene-styrene copolymer (PC/ABS) blend matrix with varying blend ratios (100/0, 80/20, 60/40, 50/50, 40/60, 20/80, and 0/100) and a constant filler content (2 wt % MWCNT and 2 wt % nanographite). Furthermore, the PC/ABS (40/60) blend-based nanocomposite was prepared with the addition of a compatibilizer, 5 wt % of maleic anhydride grafted ABS (ABS-g-MAH), to verify possible changes in morphology. Morphology, rheology, mechanical, electrical, and electromagnetic properties were correlated. From a morphological perspective, a preferential distribution of MWCNTs within the PC phase was observed, with the different blend ratios leading to a transition from a dispersed matrix morphology in 80/20 and 20/80 (PC/ABS) to cocontinuous morphologies in the intermediate blends (60/40, 50/50, and 40/60). The addition of ABS-g-MAH as a compatibilizer resulted in significant morphological refinement. Electromagnetic properties, evaluated using both X-band rectangular waveguide and broadband coaxial airline techniques, as well as electrical conductivity, were found to be strongly influenced by the varying morphologies. The nanocomposite PC/ABS/ABS-g-MAH with a thickness of 3.0 mm presented a Reflection Loss (RL) of −29.4 dB at 9.44 GHz, with a bandwidth of 3 GHz. Across the broadband spectrum, RL values below −10 dB were observed, including at lower frequencies around 3.70 GHz. These findings suggest that morphological tuning of the polymer matrix offers a promising pathway for optimizing microwave absorption in hybrid nanocomposites.