Production of <i>Rhizopus oryzae</i> by solid state fermentation and evaluation of its biocomposite characteristics

<i>Rhizophus oryzae</i> biomass (RB) can be incorporated into polylactic acid (PLA) to create improved biocomposites that perfectly fit the biobased circular economy model. In this study, <i>Rhizopus oryzae</i> EGE-F75, produced through solid-state fermentation in aluminum trays with the maximum RB production conditions (Initial moisture (%): 79.84%, Inoculum ratio (%): 28.01, Incubation time (days): 9.74) was used as reinforcement material in PLA biocomposites. Biocomposites were obtained by adding varying amounts of RB (5% and 10% by weight) to PLA using a twin screw extruder, and the physical, thermal, mechanical and morphological properties of the biocomposites were investigated. According to the results, the incorporation of RB resulted in a decrease in mechanical properties. The tensile strength of 10% RB/PLA composite decreased by 23%, while the flexural modulus value of the composite increased by 6% compared to PLA. Furthermore, the addition of RB to PLA delayed the thermal decomposition of PLA and reduced its thermal conductivity. Introducing 5 wt% of RB to the PLA matrix reduced the thermal conductivity of the PLA matrix by 79%. Therefore, RB may not serve as an ideal filler for enhancing the mechanical properties and thermal stability of biocomposites, but it does offer potential as an alternative material for thermal insulation.