Multifunctional poly (lactic acid) biofilms reinforced with selenicereus undatus peel powder: Structure - Property relationships and sustainable packaging performance

The production of biodegradable films using polymers derived from renewable sources can offer a recyclable substitute to petroleum-derived polymers. In the current work, PLA biofilms incorporated with 5- 25 wt% Selenicereus Undatus peel powder (SUPP) were prepared by the solution casting method, and the properties of these films, such as morphology, thermal stability, mechanical strength, surface properties, barrier properties, optical and biodegradation characteristics were analyzed. FTIR and XRD analyses confirmed the successful incorporation of SUPP into PLA, with characteristic functional groups and changes in crystallinity and crystallite structure. SEM analysis demonstrated uniform distribution and good interfacial contact with the PLA matrix up to 20 wt% of SUPP; however, some particle agglomeration was seen beyond this loading level. TGA results indicated that the thermal stability of the films was enhanced due to the presence of SUPP because the maximum degradation temperature increased from 293.8°C for pristine PLA to 367.4°C for PLA/25 wt% SUPP. The mechanical strength of the biofilms was substantially increased, with tensile strength and young’s modulus of 37.8 MPa and 51.9 MPa, respectively, at 20 wt% of SUPP. The 31.9% decrease in WVTR from neat PLA to PLA/25% SUPP, demonstrating improved moisture-barrier performance. The addition of SUPP increased the puncture resistance, surface roughness, ink adhesion, and UV blocking ability. Soil burial test showed reduced degradation with increasing SUPP content, from 41% for neat PLA to 23.5% for PLA/25% SUPP. Overall, PLA/SUPP biofilms, especially with 20 wt% SUPP, showed improved properties and strong potential for sustainable packaging.