Enhanced biodegradability and thermal insulation capability of polylactic acid reinforced with calcium-crosslinked orange peel biochar

The growing demand for sustainable materials has driven interest in biodegradable polymers such as polylactic acid (PLA). However, PLA’s inherent limitations in thermal insulation and flame retardancy restrict its broader applicability. To address these challenges, we produced PLA composites reinforced with various amounts of calcium-crosslinked orange peel biochar (CC-OPB) and discovered that the latter significantly enhanced the thermal and flame-retardant properties of the former. The 6 % CC-OPB/PLA composite achieved the lowest thermal conductivity of 0.081 W/m·K and a V-1 rating in a UL94 plastics flammability standard test. These improvements were attributed to the formation of a protective char layer and enhanced phonon scattering. In addition, the incorporation of CC-OPB accelerated the biodegradation process, with the 6 % CC-OPB/PLA composite showing a weight loss of 25.1 % after 20 days. Our findings demonstrate that CC-OPB/PLA composites offer a promising eco-friendly alternative for industrial applications by imparting superior insulation, fire resistance, and biodegradability to PLA. • Developed a novel PLA composite reinforced with CC-OPB filler. • Achieved low thermal conductivity of 0.081 W/m·K and high flame retardancy. • Enhanced biodegradability with 25.1 % weight loss in 20 days. • Applied CC-OPB for insulation and flame resistance instead of conventional fillers.