Processing and Characterization of Poly(lactic acid) (PLA) Films Containing Pomegranate Peel Powder

Area of Science:

• Materials Science
• Polymer Science
• Sustainable Materials

Background:

• Biodegradable polymers like Poly(lactic acid) (PLA) are sought for sustainable packaging.
• Agricultural by-products, such as pomegranate peel, are rich in bioactive compounds.
• Valorizing agricultural waste into functional additives for bioplastics is an active research area.

Purpose of the Study:

• To investigate the effects of incorporating pomegranate peel powder (PoP) on the properties of PLA-based composite films.
• To evaluate the antioxidative behavior, thermal stability, and mechanical performance of PLA-PoP composites.
• To determine the optimal concentration of PoP for balancing desired functionalities and material integrity.

Main Methods:

• PLA-based composite films were prepared using melt extrusion with 1-5 wt.% PoP.
• Characterization included tensile testing, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and oxidation induction temperature (OIT).
• Fourier-transform infrared spectroscopy (FT-IR), color analysis, rheology, SEM, and UV-Vis spectroscopy were also employed.

Main Results:

• PoP incorporation did not significantly alter PLA's characteristic transition temperatures (Tg, Tm, Tc).
• Thermo-oxidative stability improved, with OIT increasing by up to 30 °C at 3 wt.% PoP.
• Mechanical properties, including tensile strength and elongation at break, decreased, indicating embrittlement at PoP concentrations ≥3 wt.%.

Conclusions:

• Pomegranate peel powder (PoP) can impart beneficial antioxidative properties to Poly(lactic acid) (PLA) films.
• Higher PoP concentrations negatively impact the mechanical integrity of PLA composites.
• Careful optimization of PoP content is necessary to achieve a balance between enhanced bioactivity and acceptable mechanical performance for sustainable applications.