Conducting <scp>PLA</scp> /Liquid Isoprene Rubber/Graphene Nanoplatelets for Green Electromagnetic Absorbing Packaging Materials

ABSTRACT Partially biodegradable, toughened, electromagnetic absorbing materials were developed using poly(lactic acid) (PLA), liquid isoprene rubber (LIR) and graphene nanoplatelets (GNP). The materials were evaluated for their morphology, tensile properties, rheological behavior, crystallization characteristics, electrical conductivity and electromagnetic absorptivity. GNP not only reduced the interfacial tension between PLA and LIR, but also acted as a nucleating agent. The incorporation of LIR and LIR/GNP (5 phr GNP) significantly improved the toughness of the PLA matrix. The electrical percolation threshold for the PLA/LIR/GNP composite was determined to be 3.02 vol% GNP. Electromagnetic absorption was studied in both monolayer (bulk) and bilayer configurations, with layers of identical composition. The bulk materials showed optimal absorption performance at a thickness of 2 mm, achieving a minimum reflection loss (RL) of −25 dB and an effective absorption bandwidth (EAB) below −10 dB spanning 5.12 GHz, with 15 phr GNP. Bilayer samples, particularly those containing more than 7 phr GNP, exhibited broader EABs compared to their bulk counterparts. In conclusion, the synergistic combination of LIR and GNP enhanced the mechanical, electrical and electromagnetic properties of PLA, making these composites promising candidates for use in electromagnetic shielding for electronic packaging and stealth technology aimed at reducing radar detectability.