Effect of Oligoricinoleic Acid on Degradation of Polylactic Acid

ABSTRACT

The objective of this research is to explore the impact of oligoricinoleic acid (ORA) on the degradation of polylactic acid (PLA). ORA was synthesized from ricinoleic acid using tin (II) 2-ethylhexanoate as a catalyst. The chemical structures of the obtained ORA were confirmed by Fourier-transform infrared spectrometer (FT-IR) and proton nuclear magnetic resonance spectroscopy (¹H-NMR). PLA/ORA films were prepared through the casting method by varying ORA concentrations as 0.1%wt, 0.3%wt, 0.5%wt, 1.0 wt%, and 3.0%wt. Degradation of the films via hydrolysis was studied by soaking the films in deionized water and stirring at 120 rpm in an incubator at 37°C. Alterations in the structure and properties of the films were investigated after soaking for 7, 14, 21, and 28 days using ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectrometer (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), and universal testing machine (UTM). Gel permeation chromatography (GPC) was performed to confirm the decrease in molecular weight (M_W). The presence of 3%wt ORA could promote both ductility and degradation of PLA films. ORA further enhances thermal stability, indicating potential for prevention of thermal degradation during melt processing.

GRAPHICAL ABSTRACT

KEYWORDS:

• Degradation
• hydrolysis
• oligoricinoleic acid
• polylactic acid

Acknowledgments

This work was supported by the Faculty of Engineering, Kasetsart University under Grant [number 65/01/MATE/D.Eng]. Additionally, the Department of Materials Engineering, Kasetsart University provided partial funding and equipment support.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by the Faculty of Engineering, Kasetsart University [65/01/MATE/D.Eng].

Notes on contributors

Pinuma Kaewruksa

Pinuma Kaewruksa is a Ph.D. student at Department of Materials Engineering, Faculty of Engineering, Kasetsart University under the guidance of Asst. Prof. Amornrat Lertworasirikul. Her research focused on the development of polymer degradation.

Amornrat Lertworasirikul

Amornrat Lertworasirikul is an assistant professor specializing in polymer at the Department of Materials Engineering, Faculty of Engineering, Kasetsart University, Thailand. Her academic background includes a B.S. in Materials Science and an M.S. in Polymer Science, both obtained from Chulalongkorn University, Thailand. She earned her D.Eng. in Biotechnology and Life Sciences at Tokyo University of Agriculture and Technology, Japan. Her expertise lies in the areas of chemical modification, characterization, and processing of bio-based polymers, biomaterials, and functional polymers.