Evaluation of Mechanical Properties of Polylactic Acid (PLA) Films Over One and Ten Months of Aging

Articles in Press

Document Type : Research Article

Authors

• N. Tajari ¹
• H. Sadrnia ¹
• F. Hosseini ²

¹ Department of Biosystems Engineering, Ferdowsi University of Mashhad, Mashhad, Iran

² Department of Food Additives, Iranian Academic Centre for Education Culture and Research (ACECR), Mashhad, Iran

10.22067/jam.2025.90838.1316

Abstract

Polylactic acid (PLA) is a thermoplastic, biodegradable, and bioactive polymer obtained from renewable resources such as beets and potatoes. PLA is regarded as a polymer that is nearly brittle, which can restrict its applications in the packaging industry. The mechanical properties of this polymer can be improved by adding nanoparticles and plasticizers. In this research, zinc oxide nanoparticles (1 wt% of PLA), Polyethylene glycol 400 (20 wt% of PLA), and Polysorbate 80 (0.25 wt% of the solution) were used to improve the mechanical properties of PLA films. The effects of these materials on the films were measured at two time points: the first month and the tenth month, with the aim of investigating physical aging, a precursor to polymer degradation. Statistical analysis was performed on the mechanical properties measured during these periods to identify significant differences between the produced films. Results showed that the highest tensile strength (82.99± 1.90 MPa, neat PLA), elongation at break (76.82± 27.22 %, PLA/PEG/ZnO), toughness (20.13± 7.89 J cm^-3, PLA/PEG/ZnO), and Young's modulus (2.74± 0.10 GPa, neat PLA) were observed in the first month. Analysis of variance results regarding the effect of time on each film revealed that in most cases, the mechanical properties did not change significantly after ten months. Based on the stress-strain curves, it was found that the neat PLA film is among the resistant materials. The PLA/Polysorbate/ZnO film exhibited brittle behavior in the tenth month. The remaining samples exhibited characteristics that fell between resistant and ductile materials in both the first and tenth months.

Keywords

• Mechanical properties
• Physical aging
• PLA
• ZnO nanoparticles

Main Subjects

• Nanotechnology (packaging films, biocomposites, solar cells)

©2025 The author(s). This is an open access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0).

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