Synthesis and characterization of lightweight unmanned aerial vehicle composite building material for defense application

In this study, a lightweight unmanned aerial vehicle composite material for defense purpose was prepared using green pea pods ( Pisum sativum ) lignin macromolecule, industrial hemp fiber, and polyester resin. The primary objective of this research was to investigate how the addition of lignin improves the load bearing, wear, and flammability properties of hemp fiber–reinforced polyester composite. The lignin was synthesized from recycled green pea pod wastes via modified thermo-chemical process and utilized for composite making. The results indicated that the addition of lignin shows improvement in mechanical properties. Similarly, a significant improvement in wear resistance occurred at an increase of lignin volume up to 4.0, which is equal to 0.103 mm 3 /Nm of sp. wear rate and 0.35 of COF. However, the maximum fatigue life counts of composite containing 2.0 vol.% of lignin records 36,972 at 25% of UTS. Moreover, inclusion of lignin up to 4.0 vol.% retains higher hydrophobicity as neat resin with the lowest propagation flame speed of 11.90 mm/min. This load bearing, wear, and flammability properties improved lightweight composites which could be used as a building material for unmanned aerial vehicles in defense, morphing wing, and surveillance drones.