Tailoring Mechanical Properties of Natural Mucilage Films via Plasticizer Incorporation: Toward Sustainable Material Innovation

Cissampelos pareira , locally known as Krueo Ma Noy or Monoi, is a traditional Thai medicinal plant whose leaf mucilage has long been used as an edible gel and dessert ingredient. The mucilage, a natural hydrophilic polymer produced by plant metabolism, possesses film-forming potential that could be useful in pharmaceutical applications. This study aimed to develop and evaluate the mechanical properties of films prepared from dried C. pareira leaf mucilage, with the incorporation of various plasticizers—glycerin (Gly), propylene glycol (PG), polyethylene glycol-400 (PEG-400), and low-protein natural rubber latex (LPNRL)—to enhance film flexibility and usability. The unplasticized mucilage film exhibited a high tensile strength of 15.81 ± 0.58 MPa but was brittle, with low elongation at break recorded at 1.62 ± 0.24 percent. The addition of plasticizers significantly improved film elasticity, increasing elongation to a range of 21.41 to 29.93 percent, while reducing tensile strength to between 6.10 and 10.73 MPa. Among the plasticizers tested, LPNRL showed the most favorable mechanical profile, providing a flexible yet sufficiently strong film structure. These results indicate that C. pareira mucilage, when properly modified, can serve as a sustainable and biodegradable alternative for use in pharmaceutical film formulations, including wound dressings, transdermal systems, or oral thin films.